Teng, T.H. Jayamani, E., Bakri, M.K.B., Sia, C.V. Law, P.L, Baini, R., Chong K.H. (2020) Effect of Biomass Ash Mixture Composite on Sound Absorption. Materials Today: Proceedings 29 (1), 223-227.

Abstract: Given that noise is an unwanted variable in human comfort whether in industrial or in commercial application, biomass combustion in recent days has gained increased interest within the heat and power industries; moreover, the application of biomass ash is used widely in many sectors. However, the effectiveness of sound absorption by various biomass ash mixture remains unexplored. This research aims at evaluating the effect of biomass ash mixture composite, in particular, coconut coir and spent coffee ground, toward sound absorption. It is formulated on the ratios of 1:1, 1:2, 1:3, 2:1 and 3:1 of epoxy resin to biomass ash via standing wave tube according to ASTM E1050-98. The results obtained from the research’s experiments indicated that, at 5 kHz, the average sound absorption coefficients for epoxy specimen infused with coconut coir ash, coffee ash, and mixture of both ashes, are 0.1, 0.098, and 0.097, respectively, and that the unmingled epoxy specimen has an average sound absorption coefficient of less than 0.09. Therefore, the research concluded that coconut coir ash composite provides better sound absorption property, compared to coffee ash, mixture of both ashes, and purely epoxy composites.

Link: Materials Today: Proceedings

Jayamani, E., Rahman, M.R., Benhur, D.A., Bakri, M.K.B., Kakar, A., and Khan, A. (2020), "Synthesis and Characterization of Micro-nano Carbon Filler from Jatropha Seeds", BioResources, 15(3), 5514-531.

Abstract: This paper discusses mechanical, morphological, infrared spectral, and thermal properties of fly ash/sugarcane fiber reinforced epoxy polymer composites. Samples were prepared with and without the addition of 2 wt% of fly ash. Sugarcane fiber additions were varied from 0 wt% to 10 wt%(with an increment of 2 wt% for each sample), while the epoxy was used as a binder. A comparative study of these properties was completed on samples with and without the addition of fly ash in the composites. Based on the results obtained, the addition of 2 wt% of fly ash improved the tensile strength and hardness properties but reduced the flexural strength of the composites. Additions of fly ash reduced bubble or void formation in the composites, while toughening the composites and improving adhesion between the fiber and matrix. Samples with 4 w% of fiber and 2 wt% of fly ash composites showed high tensile strength and hardness properties, while 2 wt% of fiber composites showed high flexural strength.

Link: BioResources

Nyuk Khui, P.L., Rahman, M.R., Hamdan, S., Jayamani, E., Bakri, M.K.B., and Sanaullah, K. (2020), "Synthesis and Characterization of Micro-nano Carbon Filler from Jatropha Seeds", BioResources, 15(2), 3237-3251.

Abstract: Biochar was synthesized from biomass (jatropha seeds) through a low microwave pyrolysis temperature of 180 °C with microwave power of 2kW. A ball milling process reduced the jatropha seed biochar size and converted it into micro-nano carbon biofiller. After ball milling, the biochar size was reduced from 1 to 3 mm to the 10 µm to 600 nm range, which is around a 90% reduction in size. Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and Brunauer-Emmett-Teller (BET) analysis were used to determine the jatropha seed biofillers properties with respect to the ball milling processes. BET results revealed increasing surface area from 0.10 to 3.67 m2/g, and EDS results revealed the elemental composition of the jatropha seed biofillers. The carbon mass percentage increased from 72.6 to 81.2%. Both results were after ball milling for 30 hours. The FTIR results revealed an increase in transmittance intensity and some reduction in peaks after ball milling. Production of micro-nano carbon fillers from microwave pyrolysis jatropha seeds biochar are applicable as reinforcement fillers for high strength composite material fabrications. Scanning electron microscopy, EDS, FTIR, and BET analysis results indicated size reduction of the biochar with increased carbon content from 72.6 to 81.2% as surface area increased from 0.10 to 3.67 m2/g after 30 hours of ball milling.

Link: BioResources

Rahman, M.R., Hamdan, S., Baini, R.B., Bakri, M.K.B., Adamu, M., Nyuk Khui, P.L., Kakar, A., and Sanaullah, K. (2020), "Chemically Treated Borneo Sago (Metroxylon sagu) Starch Reinforced Poly Lactic Acid Bio-composites", BioResources, 15(1), 1641-1655 .

Abstract: Properties of Borneo sago starch reinforced poly-(lactic acid) (PLA) composites were evaluated, with attention to the effects of treatment with acrylic acid, benzene diazonium chloride, and tetrahydrofuran. The PLA-sago composites treated with tetrahydrofuran had the highest tensile strength, with a maximum value of 0.85 MPa at 20 wt%; whereas the PLA-sago composites treated with benzene diazonium chloride had the highest modulus of elasticity, with a maximum modulus of elasticity of 28 kPa at 5 wt%. Scanning electron microscopy images of the surfaces showed good interfacial contact between the PLA and the sago starch treated with benzene diazonium chloride. The Fourier-transform infrared spectra revealed the functional group characteristics of the chemicals composition of the materials. According to the thermogravimetric analysis results, all of the composites displayed thermal stability up to a temperature of 300 °C. The differential scanning calorimetry analysis revealed that the poly lactic acid-sago composites treated with benzene diazonium chloride had the highest melting point.

Link: BioResources

Nyuk Khui, P.L., Rahman, M.R., Hamdan, S., Bakri, M.K.B., Jayamani, E., and Kakar, A. (2019), "Effect of Nano-enhancement on Acacia Wood Bio-composites", Rahman, M.R. (eds), In: Acacia Wood Bio-composites - Towards Bio-Sustainability of the Environment , Vol. 1, Chapter 9, Springer, 187-205.

Abstract: This chapter explain about nano-enhancement on acacia wood bio-composites. The tensile, flexural and impact tests were describe in this study. The optimum tensile strength was achieved at 10 wt% weight percentage for both U-AW-NCHB-PLA/PHA and M-AW-NCHB-PLA/PHA bio-composites. The optimal flexural strength for AW-NCHB-PLA/PHA bio-composites was achieved at 10 wt% weight percentage for both U-AW-NCHB-PLA/PHA and M-AW-NCHB-PLA/PHA bio-composites. The optimal impact strength for AW-NCHB-PLA/PHA bio-composites was achieved at 10 wt% fiber loadings for both U-AW-NCHB-PLA/PHA and M-AW-NCHB-PLA/PHA bio-composites. Nano-clay enhancement increased the viscosity of the polymer blend, hence increases the threshold mechanical strength of the bio-composites. A strong adhesion was created between fiber and polymer, due to the incorporation of nano-clay, which reduces the agglomeration and formation of void during fabrication. It was observed that the U-AW and NCHB-PLA/PHA has a smooth surface structure and could be considered as semi-brittle/semi-ductile.

Link: Acacia Wood Bio-composites - Towards Bio-Sustainability of the Environment

Bakri, M.K.B., Nyuk Khui, P.L., Rahman, M.R., Hamdan, S., Jayamani, E., and Kakar, A. (2019), "Dielectric Properties of Acacia Wood Bio-composites", Rahman, M.R. (eds), In: Acacia Wood Bio-composites - Towards Bio-Sustainability of the Environment , Vol. 1, Chapter 8, Springer, 171-186 .

Abstract: In this chapter, pure PLA, PHA, PLA/PHA (1:1 ratio of PLA/PHA), and NCHB-PLA/PHA (1 wt% of NCHB; 1:1 ratio of PLA/PHA) with addition of different fiber loadings (i.e. 5 wt%, 10 wt%, 15 wt% and 20 wt%) are fabricated. It is found that the addition of Acacia wood (AW), caused an inrease in the dielectric constant, dissipation factor and loss factor. The highest optimum value was obtained at 20 wt% fiber loadings. Addition of AW fiber caused an increase in the dielectric constant, dissipation factor and loss factor. Chemical modification on the AW fiber were also done and resulted, which resulted in the increase of hydrophobicity of the modified AW fiber. Polymer blend created better interlocking, reduce the formation of bubble/void, which create low dielectrical properties than PLA and PHA itself. Addition of NCHB stabilizes the dielectric constant, dissipation factor and loss factor, which led to a smoother data, when compared to other results.

Link: Acacia Wood Bio-composites - Towards Bio-Sustainability of the Environment

Jayamani, E., Tan, H.L., Benhur, D.A., and Bakri, M.K.B. (2019), "Environmental Impact Analysis of Wood and Natural Fiber Bio-Composites", Rahman, M.R. (eds), In: Acacia Wood Bio-composites - Towards Bio-Sustainability of the Environment , Vol. 1, Chapter 7, Springer, 153-170.

Abstract: In this chapter, a brief review on the practicability of using fiber reinforced polymer (FRP) in construction applications, particularly in the reinforced concrete structures were reported. The environmental and performance issues of conventional building materials such as concrete and steel were discussed in detail. The prospect of implementing FRP composite in this area was also discussed. To assess the undesirable environmental burdens of using FRP, the fundamental concept, procedures and several components of LCA have been discussed thoroughly. The existing LCA case studies on different materials were also critically reviewed for better understanding. The effects of the composition variation in the FRP system on the environment were also examined in this chapter. The popularity of LCA particularly in the use of composites in construction industry has been very low, due to the inherent complexities associated with the building itself.

Link: Acacia Wood Bio-composites - Towards Bio-Sustainability of the Environment

Bakri, M.K.B., Rahman, M.R., Hamdan, S., Nyuk Khui, P.L., Jayamani, E., and Kakar, A. (2019), "Infrared Spectral Functional Group and Thermal Properties of Acacia Wood Bio-composites", Rahman, M.R. (eds), In: Acacia Wood Bio-composites - Towards Bio-Sustainability of the Environment , Vol. 1, Chapter 6, Springer, 135-151 .

Abstract: This chapter discover spectral functional group and thermal properties of acacia wood bio-composites. A small peak at 2897.08 cm⁻¹ for U-AW fiber and 2900.94 cm⁻¹ for M-AW fiber was attributed to the C-H stretching and O-H stretching bond structure that contained functional group of alkanes (cellulose and lignin) and carboxylic acids. The small peak in the region of the C-H stretching bond structure can also include a functional group of methyl (CH3), methylene (CH2), and aliphatic saturated (CH). The peak at 607.58 cm⁻¹ and 592.15 cm⁻¹ for U-AW fiber, and 605.65 cm⁻¹, 559.36 cm⁻¹, 493.78 cm⁻¹ and 472.56 cm⁻¹ for M-AW fiber is characterized as the =CH bending bond structure from the functional group of alkenes (lignin). Few additional peaks in M-AW fiber spectrum were due to the esterification, which promotes additional free hydroxyl structure, which improves the AW fiber structure for better adhesion with polymer. The peak at 943.19 cm⁻¹ and 727.16 cm⁻¹ for PLA/PHA, and 875.68 cm⁻¹ and 719.45 cm⁻¹ for NCHB-PLA/PHA is characterized as the C-H “oop” bond structure from the functional group of aromatics. The peak at 480.28 cm⁻¹ for NCHB-PLA/PHA is characterized as the =CH bending bond structure from the functional group of alkenes. The DSC result prove that the reduction in the crystallinity values was an indicator of improvement in the adhesion between fiber and polymer in the bio-composites. The TGA result demonstrated that M-AW-PLA/PHA blend showed two degradation steps. The first step was due to decomposition of hemicellulose, and lignin, weak PHA and PLA bonding and the second step was degradation of cellulose, strong PLA and PHA and other bonding in the polymer blend.

Link: Acacia Wood Bio-composites - Towards Bio-Sustainability of the Environment

Nyuk Khui, P.L., Rahman, M.R., Hamdan, S., Bakri, M.K.B., Jayamani, E., and Kakar, A. (2019), "Study of Surface Behavior of Acacia Wood Bio-composites by Morphological Analysis", Rahman, M.R. (eds), In: Acacia Wood Bio-composites - Towards Bio-Sustainability of the Environment , Vol. 1, Chapter 5, Springer, 121-134.

Abstract: This chapter describe the surface performance and morphological analysis of acacia wood bio-composites. The SEM images of U-AW-PLA and U-AW-PLA showed a big void between the fiber and polymer. It could be observed that the U-AW has a smooth surface structure whereas the PLA structure was brittle. Impurities influences the properties, where oily and waxy structure of U-AW fiber causes poor adhesion and absorbance between PLA matrix and U-AW fibre. The U-AWPHA and U-AW-PHA shows a void between fiber and polymer and it was observed that the U-AW and PHA structure is smooth and ductile, while U-AW-PHA exhibited the de-bonding between fiber and polymer. Impurities such as the waxy and oily structure of AW fiber influences the properties, hence caused poor adhesion and absorbance between U-AW fiber and PHA. It could be observed from the SEM images that the U-AW and NCHB-PLA/PHA has a smooth and semibrittle/semi-ductile structure. The resulting properties could be caused by impurities such as the oily and waxy structure of U-AW fiber, hence affecting the composite sample by having poor adhesion and absorbance between U-AW fiber and NCHB-PLA/PHA.

Link: Acacia Wood Bio-composites - Towards Bio-Sustainability of the Environment

Nyuk Khui, P.L., Rahman, M.R., Hamdan, S., Bakri, M.K.B., Jayamani, E., and Kakar, A. (2019), "Tensile, Flexural and Impact Strength of Acacia Wood Bio-composites", Rahman, M.R. (eds), In: Acacia Wood Bio-composites - Towards Bio-Sustainability of the Environment , Vol. 1, Chapter 4, Springer, 103-119.

Abstract: This chapter explores the tensile, flexural and impact strength of acacia wood biocomposites. The tensile strength of U-AW-PLA and M-AW-PLA bio-composites at different fiber loadings show that 15wt% fiber loading increment 23% compare to pure PLA. Flexural strength for AW-PLA bio-composites was achieved at 15wt% fiber loadings for both U-AW-PLA and M-AW-PLA bio-composites. The percentage of decrement for 15wt% U-AW-PLA is about 1% than the pure PLA. The impact strength for AW-PLA bio-composites was achieved at 15wt% fiber loadings for both U-AW-PLA and M-AW-PLA bio-composites. The percentage of increment for 15wt% U-AW-PHA is about 6% than the pure PHA whereas 15wt% M-AW-PHA is about 4% than the 15wt% U-AW-PHA. The polymer blends (PLA/PHA) bio-composites created desirable mechanical properties (tensile, flexural and impact strength) than the PLA and PHA polymer bio-composites itself due to the interlocked structure.

Link: Acacia Wood Bio-composites - Towards Bio-Sustainability of the Environment

Jayamani, E., Zain, M. Rahman, M.R., and Bakri, M.K.B. (2019), "Acacia Wood and Its Surface Treatment for High Strength Bio-composites", Rahman, M.R. (eds), In: Acacia Wood Bio-composites - Towards Bio-Sustainability of the Environment , Vol. 1, Chapter 2, Springer, 23-48.

Abstract: Till date, the core issue amongst many ecological problems that we face has been about nature and its various pollutions. Wood and natural fiber were known to be the very first materials used to combat noise pollution due to its miraculous properties of high strength and high sound absorption. It was employed as the initial material to reduce the high levels of noise in the harsh environment. Gradually, wood, natural fiber and its waste have become abundant. Moving on, agricultural lignocellulosic materials are also seen as environmentally friendly, reproducible and sustainable fibers. To counter this problem, researchers headed towards the use of synthetic materials that could reduce this problem. It is known that natural fiber and wood composite materials are analyzed to be weak in mechanical properties when compared to synthetic polymer composites, but the sustainability factor insisted the researchers to serve the cause of improving the mechanical properties of natural fiber composite materials. Various methods have now been established to improve and analyze the surface characteristics of wood and natural fibers and hence the mechanical properties of natural fiber composite materials. In this study, a thorough literature review is conducted on the chemical and physical treatment of wood and lignocellulosic residues and their characterization.

Link: Acacia Wood Bio-composites - Towards Bio-Sustainability of the Environment

Rahman, M.R. Kakar, A., Hamdan, S. Bakri, M.K.B., Julai, N, and Nyuk Khui, P.L. (2019), "Introduction of Various Types of Acacia Wood", Rahman, M.R. (eds), In: Acacia Wood Bio-composites - Towards Bio-Sustainability of the Environment , Vol. 1, Chapter 1, Springer, 1-21.

Abstract: Genus Acacia has a complex history in globally, there are categorize them as plants, shrubs, and large trees. This chapter covers various types of acacia species, and plantation of Acacia trees in regions such as Malaysia and Portugal. Some Acacia species are valued while others are considered as an invasive species towards the surrounding region of flora. Numerous methods were applied to control such invasive species, one of the alternative method of control is the application of acacia wood as timber product for wood industries. Heartwood and sapwood content are one of the important features in timber, as the content affects the quality, durability and susceptibility of the product which is attack by fungi. Some studies reported a relatively high heartwood content in acacia woods in acacia tree plantations, hence acacia timber has potential as a desirable wood working material and other commercial or industrial applications.

Link: Acacia Wood Bio-composites - Towards Bio-Sustainability of the Environment

Rahman, M.R., Hamdan, S., Jayamani, E., Kakar, A., Bakri, M.K.B., and Md. Yusof, F.A.B., (2019), "The Effect of Palm Oil Fuel Ash (POFA) and Polyvinyl Alcohol (PVA) on the Physico-Mechanical, Thermal, and Morphological Properties of Hybrid Bio-Composites", Polymer Bulletin, 1(1), 1-13.

Abstract: This study focuses on the effects of palm oil fuel ash (POFA) and polyvinyl alcohol (PVA) on the physico-mechanical, thermal and morphological properties of kenaf-/jute-reinforced polyvinyl alcohol (PVA)/polyethylene (PE) hybrid bio-composites. The fibers were dried in an oven and mixed with PE and PVA at different fiber loadings, respectively (5 wt%, 10 wt%, 15 wt% and 20 wt%). The samples were prepared and tested according to ASTM standards. The scanning electron microscope shows that PVA reduces the agglomeration and increases the bonding between fiber and matrix. Jute/kenaf—PE/PVA composites (JKPEPVAC), show a higher tensile strength and Young’s modulus compared to jute/kenaf—PE composites (JKPEC), and jute/kenaf—PE/POFA composites (JKPEPOFAC). The composites have better compatibility between fiber, matrix and the PVA composite, which shows desirable properties and performances. TGA and DSC analysis confirms that the JKPEPOFAC has a higher thermal decomposition and activation energy and more thermal stability than JKPEC and JKPEPVAC.

Link: Polymer Bulletin

Jayamani, E., Ting, G.L., and Bakri, M.K.B., (2019), "Comparative Study of Fourier Transform Infrared Spectroscopy (FTIR) Analysis of Natural Fibres Treated with Chemical, Physical and Biological Methods", Polymer Bulletin, 1(1), 1-25.

Abstract: Kenaf and luffa fibres are hydrophilic due to the presence of water sensitive constituents, which tend to form a poor compatibility when binding with polymers. Thus, the surface of fibres was modified through fungal, alkaline and heat treatment to reduce the main hydroxyl functional groups (O–H) that caused the water absorption as well as to cleave the formed hydrogen bonds that hindered the compatibility. The samples were treated with Phanerochaete Chrysosporium (PC) and Fusarium Oxysporum fungi separately for 5, 10 and 15 days. Furthermore, the samples were alkaline treated with 5 wt% of sodium hydroxide at increased temperature of 25 °C, 50 °C, 70 °C and 90 °C, where it showed improvement in the hydrogen bond removal rate. Moreover, the samples that heat treated under higher temperatures of 120 °C, 140 °C, 160 °C and 180 °C were found to have the lower cellulose and hemicellulose contents due the evaporation of water molecules. Generally, through Fourier transform infrared spectroscopy analysis, both the fibres treated with PC fungi had the lowest O–H content due to the detection of the largest reduction of the O–H stretching band intensity compared to others. Furthermore, the highest weight loss and the lowest water absorption percentages were also detected from these fibres, which also indicated the good modification between the fibres and the PC fungi. Therefore, the fungal treatment using PC fungi is the most effective and environmentally friendly method to improve the fibres’ hydrophobic property.

Link: Polymer Bulletin

Nyaru, V., Jayamani, E., Srinivasulu, M., Eugene, C.W.H., and Bakri, M.K.B., (2019), "Short Review on Conductive Polymer Composites as Functional Materials", Key Engineering Materials, 796(1), 17-21.

Abstract: Conductive polymer composites start to gain its attention towards many industries. Widely, it is used in producing electrical components such as microchips and semiconductor electronics. Most of the highly conductive polymer composites are used to produce solar panels, which convert thermal energy into electrical energy to generate electricity. It can also diffuse heat faster to avoid overheating of components that can cause degradation of the composites in the component. Thus, this short review describes the various effects that affect the thermal conductivity of natural fiber reinforced polymer matrix composites with additions of metallic filler. The outcome of this short review helps identify the important keys that influence the conductive polymer composites as functional materials.

Link: Key Engineering Materials

Bakri, M.K.B., Jayamani, E., Soon, K.H., and Kakar, A., (2018), "Analysis of Acacia Wood Reinforced PLA/PHA Blends Composites", Materiale Plastice, 55(4), 465-468.

Abstract: This research focuses on the analysis of acacia wood reinforced PLA/PHA blend composites. Acacia wood was processed into small chip particles, which were mixed with pure PLA, pure PHA and PLA/PHA blend. The wood was treated using acetic acid and sodium bicarbonate. It was then compressed into sheet film. The micrograph shows that the PLA and PHA mixture create an interlocking continuous structure and the addition of wood strengthens interlocking between PLA and PHA. Mixtures of this blend also reduce bubble and crack, and create new properties superior than the earlier properties of existing PHA and PLA.

Link: Materiale Plastice

Jayamani, E., Hamdan, S., and Bakri, M.K.B., (2018), "Sustainable Noise Control Materials Based on Bamboo/Unsaturated Polyester Composites: Analysis of Factors Affecting the Sound Absorption Coefficients", Padinjakkara, A., Thankappan, A., Souza Jr., F.G., Thomas, S. (eds), In: Biopolymers and Biomaterials, Vol. 1, Chapter 7, Apple Academic Press/CRC Press, 101-114.

Abstract: The aim of the current chapter is to develop sustainable composites made of bamboo fibres as foundation materials for noise control applications. Fibres extracted from bamboo and plants were obtained and sodium hydroxide (NaOH) was used to treat them. These fibres were used as reinforcement for unsaturated polyester, with 5/95, 10/90, 15/85 and 20/80 blend ratio weight. The composites were fabricated by using compression moulding technique. According to the American Society for Testing and Materials, ASTM 1050-12 standard, the prepared composites were subjected to acoustical tests in a two-microphone transfer function impedance tube device. Sound absorption coefficient and the factors affecting sound absorption coefficients of composites were investigated. It was indicated by the obtained results that the sound absorption depends on the fibre content and surface modification. The untreated and treated bamboo reinforced composites demonstrate a maximum sound absorption coefficient of 0.095 and 0.120, respectively, at the frequency of 5500 Hz. The Fourier transform infrared spectroscopy analysis showed that the removal of lignocellulosic components from the fibre surface influenced the increase of the sound absorption. The hollow lumen structures of bamboo fibres and fibres distributions in the polyesters are revealed by morphological studies.

Link: Biopolymers and Biomaterials

Rahman, M.R., Hamdan, S., Ngaini, Z.B., Jayamani, E., Kakar, A., Bakri, M.K.B., and Md Yusof, F.A.B., (2018), "Cellulose Fiber-reinforced Thermosetting Composites: Impact of Cyanoethyl Modification on Mechanical, Thermal and Morphological Properties", Polymer Bulletin, 1(1), 1-17 .

Abstract: This study explores the mechanical, thermal and morphological properties of untreated and cyanoethyl-treated kempas wood sawdust cellulose fiber-reinforced unsaturated polyester composites. The fiber loadings of the composites were varied from 0 to 20 wt%, with the increment of 5 wt%. The composites were tested for water absorption, and their FTIR spectroscopy, SEM and TGA results were analyzed. The FTIR results show that the fiber treatment reduces the hydroxyl groups in the cellulose, replacing them with the cyanoethyl groups. The TGA results show that the composites are stable up to 324 °C. SEM images of the treated fiber composites showed that there were no visible gaps between fibers and matrix which indicates a strong interfacial bond. From the mechanical tests, 15 wt% fiber loading composite was strongest. Among all the composites, cyanoethyl cellulose fiber unsaturated polyester composites had the most desirable mechanical and thermal properties, whereas the fiber treatment showed the improvement of interfacial bonding.

Link: Polymer Bulletin

Bakri, M.K.B., Jayamani, E., and Kakar, A., (2018), "Potential in the Development of Borneo Acacia Wood Reinforced Polyhydroxyalkanoates Bio-Composites", Key Engineering Materials, 779(1), 19-24 .

Abstract: This research focuses on the mechanical and morphological properties of acacia wood (AW) reinforced polyhydroxyalkanoates (PHA) bio-composites. Acacia woods waste in the form of sawdust was processed into short wood fiber, which was later mixed with pure PHA with different fiber loading (5wt%, 10wt%, 15wt% and 20wt%). The acacia wood fibers were chemically modified by using the naturalization technique (which used both acidic and alkaline base) using acetic acid and sodium bicarbonate. The hot press machine was used to fabricate the samples. Tensile and flexural samples were fabricated and tested according to the ASTM standards. The SEM images show that the chemically modified acacia wood reinforced PHA (M-AW-PHA) bio-composites create desirable adhesion which contributed to better mechanical strength at 15wt%, when compared with untreated acacia wood reinforced PHA (U-AW-PHA) bio-composites.

Link: Key Engineering Materials

Jayamani, E., Soon., K.H., Khui, P.L.N., and Bakri, M.K.B., (2018), "Comparative Study of Compressive Strength of Epoxy Based Bio-Composites", Key Engineering Materials, 775(1), 68-73.

Abstract: In this paper, the compressive strength of the natural fiber composites was investigated, especially on those epoxy based materials. Mulberry, cornhusk and commercialize weave jute reinforced epoxy composites were fabricated and the results were obtained through compressive test experiment. Comparison was made based on a Buransky model with the experimental results. Alkaline treatment was used to modify and alter the lumen structure of the natural fibers. It showed that the alkaline treated natural fiber composites gave promising improvement in the compressive strength compared with the raw natural fiber composites. It also showed that the misalignment angles played another vital role in in compressive strength performance. Buransky model can be used to predict the experimental results based on condition that failure occurs on the predicted misaligned angle.

Link: Key Engineering Materials

Jayamani, E., Soon., K.H., Lee. T.S., and Bakri, M.K.B., (2018), "Mechanical Properties of Chicken Feather Reinforced Unsaturated Polyester Composites", Key Engineering Materials, 775(1), 3-6.

Abstract: In this paper, chicken feather fibers (CFFs) from poultry industries were used as reinforced materials incorporated with unsaturated polyester (UP) to create composites. It is prepared by varied the percentage weight fraction of CFFs by 2wt%, 4wt%, 6wt%, 8wt%, and 10wt%. Alkaline treated potassium hydroxide (KOH) was used to alter the structure of the CFFs. From the results it showed that the tensile strength of the CFFs/UP composites was reduced. The flexural modulus has optimum results of 35.3MPa, improved by 11.86% from pure UP (31.1MPa). For flexural modulus at 2wt% and 4wt% the untreated CFFs/UP performed better performance. However, started at 6wt% onwards, chemically treated fibers surpass untreated fiber. Even though CFFs has unique characteristics properties such as hollow honeycomb structure and low density, the poor adhesion due to its smooth surface roughness and uneven distribution of fiber during mixing contributed to the low strength and flexural values. Thus, treatment caused changes in the structure of the CFFs to increase the surface roughness of the fibers, which improve adhesion.

Link: Key Engineering Materials

Rahman, M.R., Hamdan, S., Jayamani, E., Kakar, A., and Bakri, M.K.B., and Yusof, FAM (2018), "Tert-butyl Catechol/Alkaline-Treated Kenaf/Jute Polyethylene Hybrid Composites: Impact on Physico-Mechanical, Thermal and Morphological Properties ", Polymer Bulletin, 0(0), 1-22.

Abstract: This review paper explores the potential of commercial production and application of Acacia wood—polylactic acid (PLA), and Acacia wood—polyhydroxyalkanoates (PHA) bio-composites. The factors affecting the mechanical and physical properties of these materials were identified and deliberated. It was found that Acacia wood has the prospective to be efficiently produced and used in Borneo. It can be used in a variety of applications, including but not limited to: fire breaker, timber resource, furniture production, soil re-conditioning, and as reinforced materials. Since, today, there is heightened awareness regarding sustainability, manufacturers are driven towards producing completely biodegradable products that are created using PLA and PHA bio-composites. This review provides an overview on the performance of the existing composites and bio-composites, and their implementation and utilization, while focusing on the Borneo region.

Link: Polymer Bulletin

Bakri, M.K.B., Jayamani, E., Kakar, A., and Rahman, M.R., (2018), "Improvement of Epoxy Nanocomposites on Physical, Morphology, and Mechanical Properties as Well as Fracture Behavior with the Addition of Mesoporous Silica/Nano-Silica", Rahman, M.R. (ed), In: Silica and Clay Dispersed Polymer Nanocomposites, Vol. 1, Chapter 12, Woodhead Publishing/Elsevier , 259-280.

Abstract: This part of the chapter discussed the durability and sustainability on the use of silica and clay and its nanocomposites within the wide area of industrial applications, especially with those involves in thermosetting and thermoplastics engineered polymer. It showed that the current progress, improvement, and development of silica and clay and its nanocomposites were given more impact on the advances properties toward the certain applications. Throughout this book chapter, the knowledge and fundamental understanding on the use of silica and clay properties and it challenges were observed morphologically, physically, mechanically, chemically. Thus, this chapter helps to evaluate the value of understanding of the development of silica and clay and its nanocomposites for better future applications and for those seeking for new functionality in the field of materials science.

Link: Silica and Clay Dispersed Polymer Nanocomposites

Kakar, A., Jayamani, E., Bakri, M.K.B., and Rahman, M.R., (2018), "Durability and sustainability of the silica and clay and its nanocomposites", Rahman, M.R. (ed), In: Silica and Clay Dispersed Polymer Nanocomposites, Vol. 1, Chapter 9, Woodhead Publishing/Elsevier , 137-157.

Abstract: This part of the chapter discussed the durability and sustainability on the use of silica and clay and its nanocomposites within the wide area of industrial applications, especially with those involves in thermosetting and thermoplastics engineered polymer. It showed that the current progress, improvement, and development of silica and clay and its nanocomposites were given more impact on the advances properties toward the certain applications. Throughout this book chapter, the knowledge and fundamental understanding on the use of silica and clay properties and it challenges were observed morphologically, physically, mechanically, chemically. Thus, this chapter helps to evaluate the value of understanding of the development of silica and clay and its nanocomposites for better future applications and for those seeking for new functionality in the field of materials science.

Link: Silica and Clay Dispersed Polymer Nanocomposites

Kakar, A., Jayamani, E., Bakri, M.K.B., and Rahman, M.R., (2018), "Biomedical and Packaging Application of Silica and Various Clay Dispersed Nanocomposites ", Rahman, M.R. (ed), In: Silica and Clay Dispersed Polymer Nanocomposites, Vol. 1, Chapter 8, Woodhead Publishing/Elsevier , 109-136.

Abstract: This chapter explores the structures and characteristics of clay dispersed nanocomposites, their organic modification, nanocomposite structure, and finally the mechanical properties. Based on the understanding of the fundamentals of these clay dispersed nanocomposites, the applications for these materials were evaluated. With the low weight and high strength of these nanocomposites, a wide range of biomedical and packaging applications are made possible. This includes applications from food product packaging to splints, and a body of medical devices. With the additional advantage of flame retardance, these materials may also be used for packaging highly inflammable materials. Overall, clay dispersed nanocomposites show a promising future in materials engineering, especially in biomedical and packaging applications.

Link: Silica and Clay Dispersed Polymer Nanocomposites

Jayamani, E., Tay, C.P., Bakri, M.K.B., and Kakar, A., (2018), "Comparative Analysis on Dielectric Properties of Polymer Composites Reinforced with Synthetic and Natural Fibers", Journal of Vinyl and Additive Technology, 24(S1), E201-E216.

Abstract: This article presents the study of dielectric properties of synthetic and natural fiber reinforced epoxy composites. Bamboo and glass fibers were both chopped and woven. These fibers were then used for reinforcing epoxy, with different fiber loadings. The dielectric properties of these composites were studied with reference to their fiber loadings, frequencies, and chemical treatment of the natural fibers at room temperature. It was found that dielectric properties increased with the increase in the concentration of fibers filled in the epoxy matrix, for the entire frequency range. This was due to the increase in the orientation and interfacial polarization. The treated fiber composites had lower dielectric properties due to decreased hydrophilicity of the natural fiber. The chopped glass fibers reinforced epoxy composites have the highest dielectric constant, among all tested composites.

Link: Journal of Vinyl and Additive Technology

Kakar, A., Jayamani, E., Bakri, M.K.B., and Soon, K.H., (2018), "Heat Treated Luffa - PLA Composites: Effect of Cyclic Moisture Absorption and Desorption on the Mechanical Properties", Materials Science Forum, 917(1), 42-46.

Abstract: The goal of this study was to investigate the influence of cyclic hot and cold water absorption and desorption on the flexural and impact strengths of luffa – PLA biocomposites. PLA was reinforced with heat treated luffa fibers with the fiber loadings: 5 vol.%, 10 vol.%, 15 vol.% and 20 vol.%. Based on the test results the biocomposite with the highest flexural and impact strengths was selected for water absorption and desorption cycles. The biocomposites were subjected to 56 cycles of hot and cold water absorption and desorption. The biocomposites were tested for their strengths after every 14 cycles. The absorption and desorption decreased the flexural and impact strengths, affecting the impact strength more than the flexural strength.

Link: Materials Science Forum

Bakri, M.K.B., Jayamani, E., Soon, K.H., and Kakar, A., (2018), "Short Review: Potential Production of Acacia Wood and its Biocomposites", Materials Science Forum, 917(1), 37-41.

Abstract: In this short review paper, the physical and mechanical properties of acacia wood, poly lactic acid (PLA) and polyhydroxyalkanoates (PHA) were analyzed. Existing factors that affect the mechanical properties of natural fiber composites were investigated and identified. By knowing these factors, a possibility and potentiality in implementing the natural acacia wood reinforced material with hybrid polymer were discussed. It was found that the acacia wood had the potential to re-condition soil and have the potential to become reinforced materials in hybrid polymer composites. In addition, using fully biodegradable polymer such as PLA and PHA made it sustainable and environmentally friendly.

Link: Materials Science Forum

Kakar, A., Jayamani, E., and Bakri, M.K.B., (2018), "Scarcity: Can Waste Create Value?", Campus and Beyond, The Borneo Post.

Link: The Borneo Post

Bakri, M.K.B., Jayamani, E., Hamdan, S., Rahman, M.R., and Kakar, A., (2018), "Potential of Borneo Acacia Wood in Fully Biodegradable Bio-composites' Commercial Production and Application", Polymer Bulletin, 0(0), 1-22.

Abstract: This review paper explores the potential of commercial production and application of Acacia wood—polylactic acid (PLA), and Acacia wood—polyhydroxyalkanoates (PHA) bio-composites. The factors affecting the mechanical and physical properties of these materials were identified and deliberated. It was found that Acacia wood has the prospective to be efficiently produced and used in Borneo. It can be used in a variety of applications, including but not limited to: fire breaker, timber resource, furniture production, soil re-conditioning, and as reinforced materials. Since, today, there is heightened awareness regarding sustainability, manufacturers are driven towards producing completely biodegradable products that are created using PLA and PHA bio-composites. This review provides an overview on the performance of the existing composites and bio-composites, and their implementation and utilization, while focusing on the Borneo region.

Link: Polymer Bulletin

Kakar, A., Jayamani, E., and Bakri, M.K.B., (2018), "Biomedical Materials in the Period of Scarcity", Campus and Beyond, The Borneo Post.

Link: The Borneo Post

Jayamani, E., and Bakri, M.K.B., (2018), "Lignocellulosic Fibres Reinforced Polymer Composites for Acoustical Applications", Kalia, S. (ed), In: Lignocellulosic Composite Materials, Vol. 1, Chapter 11, Springer, 415-444.

Abstract: In this chapter, an overview of various composites for sound absorption applications were reported. It includes composites made of a polymer matrix reinforced with synthetic fibres and natural fibres. New developments dealing with composites made of lignocellulosic fibre were discussed in detail and the merits and demerits of composite made of synthetic fibres and natural fibres have been discussed. In this chapter, procedures for estimating the sound absorption coefficients of various sound absorbing natural fibres were discussed with a mathematical model. Factors that may influence the sound absorption coefficients of porous materials, such as fibre size, porosity, flow resistivity, thickness, tortuosity and density were described. Empirical models to predict the flow resistivity and sound absorption coefficient were also discussed. This chapter also examines the critical issues and scientific challenges that require further research and development of polymer composite materials for their increased acceptance in the modern world for sound absorption purpose.

Link: Lignocellulosic Composite Materials

Kakar, A., Jayamani, E., Soon, K.H., and Bakri, M.K.B., (2017),"Study of Dielectric Properties of Luffa - Poly lactide Quadratic Splint Composites: The Effect of Cyclic Absorption and Desorption of Water" Journal of Vinyl and Additive Technology, 0(0), 1-7.

Abstract: This study reports on the effects of cyclic hot and cold water absorption on the dielectric properties of luffa– polylactide composites and their potential application as a quadratic mallet finger splint. The study was conducted for dry samples varying in fiber volume percentage from 0% to 20% with increments of 5%. The 15 vol% luffa–polylactide composites were subjected to the cyclic hot and cold water absorption. The changes in the dielectric constant, dissipation factor, and loss factor were measured in the 100 Hz to 1 MHz range. It was found that the higher the number of water cycles, lower the dielectric constant, dissipation factor, and loss factor. Cyclic hot water absorption showed a more significant effect on the dielectric properties than the cyclic cold water absorption.

Link: Journal of Vinyl and Additive Technology

Bakri, M.K.B., Jayamani, E., and Hamdan, S., (2017), "Processing and Characterization of Banana Fiber/Epoxy Composites: Effect of Alkaline Treatment", Materials Today: Proceedings, 4(2), 2871-2878.

Abstract: This research focuses on the development of natural fibers reinforced polymer matrix composites using agricultural waste, such as banana fibers. The banana fibers were obtained from agricultural field after banana fruit has been matured. And it underwent an alkaline treatment using 5wt% of sodium hydroxide. The composites were prepared with various fiber loadings, ranging from 5wt%, to 20wt%. The effects of alkaline treatment on the mechanical, morphological, and spectral properties were investigated and evaluated using, universal testing machine, light/optical microscope, scanning electron microscopy, and Fourier transform infrared spectroscopy. Based on the results obtained, it is noticed that a lot of factors involved in affecting the characteristics of the natural composites, such as density, fiber amount, structure agglomeration and etc. From the results obtained, treated fiber composites have superior properties as compared with untreated fiber composites.

Link: Materials Today: Proceedings

Jayamani, E., Perera, D.S., Soon, K.H., and Bakri, M.K.B., (2017), "Application of Analytic Hierarchy Process (AHP) in the Analysis of the Fuel Efficiency in the Automobile Industry with the Utilization of Natural Fiber Polymer Composites (NFPC)", IOP Conference Series Materials Science and Engineering, 191(1), 1-6.

Abstract: A systematic method of material analysis aiming for fuel efficiency improvement with the utilization of natural fiber reinforced polymer matrix composites in the automobile industry is proposed. A multi-factor based decision criteria with Analytical Hierarchy Process (AHP) was used and executed through MATLAB to achieve improved fuel efficiency through the weight reduction of vehicular components by effective comparison between two engine hood designs. The reduction was simulated by utilizing natural fiber polymer composites with thermoplastic polypropylene (PP) as the matrix polymer and benchmarked against a synthetic based composite component. Results showed that PP with 35% of flax fiber loading achieved a 0.4% improvement in fuel efficiency, and it was the highest among the 27 candidate fibers.

Link: IOP Conference Series: Materials Science and Engineering

Jayamani, E., and Bakri, M.K.B., (2017), "Preliminary Study on the Acoustical, Dielectric and Mechanical Properties of Sugarcane Bagasse Reinforced Unsaturated Polyester Composites" Materials Science Forum, 890(1), 12-15.

Abstract: In this research, the alkaline treated and untreated sugarcane bagasse was used as reinforcement with unsaturated polyester to make composites. The composites were made with 0 to 20 weight percentage of fibers using compression molding. Acoustical, dielectrical and mechanical properties of the composites were studied according to the American Society for Testing Materials (ASTM) standards. The result shows that the composites with higher sugarcane bagasse loading show higher acoustical and dielectrical properties. The composites tensile strength increased up to 10wt% of fiber loading and then starts decreasing eventually. Tensile strength and sound absorption coefficients of alkali treated fiber composites shown slightly better results than untreated fiber composites. The dielectric constant of treated fiber composites were lower compared with untreated fiber composites.

Link: Materials Science Forum

Jayamani, E., Soon, K.H., and Bakri, M.K.B., "Dielectric Properties of Pineapple Leaf Fiber Reinforced Epoxy Based Composites", Key Engineering Materials, 730(1), 42-47.

Abstract: The present study investigates the dielectric constant, loss factor and dissipation factor of pineapple leaf fiber reinforced epoxy composites as in function of fiber loading, fiber surface modification and frequency. The dielectric properties of the composites were measured using HP 16451 as the dielectric test fixture and was carried out on pineapple leaf fiber reinforced epoxy composites with varying fiber loading (5wt%, 10wt%, 15wt%, and 20wt%) and fiber subjected to sodium hydroxide treatment. It was observed that the dielectric properties of these composites were influenced by fiber loading and sodium hydroxide treatment. The dielectric constant increases with increase of fiber concentration and decrease with the increase of frequency in the case of all composites. It was also observed that the increase of dielectric constant with fiber loading was more significant at low frequency. Due to a reduction in the hydrophilic nature of pineapple leaf fiber brought about by sodium hydroxide treatment the dielectric properties of the composites was less than that of the untreated ones.

Link: Key Engineering Materials

Jayamani, E., Soon, K.H., Hamdan, S., and Bakri, M.K.B., "Comparative Study of Sound Absorption Coefficients of Coir/Kenaf/Sugarcane Bagasse Fiber Reinforced Epoxy Composites", Key Engineering Materials, 730(1), 48-53.

Abstract: This research focuses on the sound absorption coefficient of three different natural fibers reinforced epoxy composites. The natural fibers used are coconut coir, kenaf, and sugarcane bagasse. All of these fibers were mixed with epoxy resin and hardener with a ratio of 4:1. The mixtures were then poured into a circular mold and compressed by using compression molding technique. It was left for curing for 24 hours at standard room temperature. The results were obtained using the two-microphone transfer functions impedance tube method according to ASTM E1050-12. It is found that as the fiber loading increased, the sound absorption coefficient of the composites increased. 20wt% Coconut coir epoxy composites and 20wt% kenaf fiber epoxy composites have the highest sound absorption coefficient with almost similar sound absorption of 0.078 at 5000Hz. While, 20wt% sugarcane bagasse epoxy composites have sound absorption of 0.075 at 5000Hz.

Link: Key Engineering Materials

Rahman, M.R., Hamdan, S., Jayamani, E., Bakri, M.K.B., and Islam, M.S., (2017), "Biocomposite Materials and Its Applications in Acoustical Comfort and Noise Control" Jawaid, M., Salit, M.S., Alothman O.Y. (eds), In: Green Biocomposites - Design and Applications, Vol. 1, Chapter 11, Springer, 247-259.

Abstract: In this chapter, an overview of various composite materials for sound absorption applications were reported and discussed in details. This includes composites made of polymer matrix reinforced with synthetic fibers and with natural fibers. This chapter also deals with composites made of recycled materials, bio-based matrix and bio-based fiber materials, hybrid biodegradable materials and surface treatment fiber composites for sound absorption applications. New developments dealing with composite materials made of lignocellulosic fiber and the pros and cons of synthetic fibers and natural fibers were also studied. This chapter also examines the critical issues regarding on composite materials and the scientific challenges faces by researchers and industries that require further research and development of composite materials made from polymer composites for their increased acceptance in the modern world for sound absorption purpose.

Link: Green Energy and Technology

Bakri, M.K.B., Jayamani, E., Soon, K.H., Hamdan, S., and Kakar, A., (2016)"An Experimental and Simulation Studies on Sound Absorption Coefficients of Banana Fibers and their Reinforced Composites", Nano Hybrids and Composites, 12(1), 9-20.

Abstract: This research focuses on the simulation of sound absorption coefficient of banana fiber and experimentation of sound absorption coefficient of banana fiber epoxy composites. For simulation, ‘Mechel’ empirical model was used to manipulate the flow resistivity and ‘Delany and Bazley’ empirical model was used to develop the prediction of sound absorption coefficient at frequency ranges from 500 Hz to 6000 Hz. For experimentation, two-microphone transfer function impedance tube model was used to analyze the sound absorption coefficient at frequency ranges from 500 Hz to 6000 Hz. Based on simulation, it is predicted and analyzed that the sound absorption coefficient of banana fiber found to be as high as 0.97 for the effects on the material thickness of banana fiber and 0.64 for the effects on the fiber diameter size and flow resistivity of banana fiber in the frequency ranges from 500 Hz to 6000 Hz. According to experimental results, it is observed and analyzed that the sound absorption coefficient of banana epoxy composites found to be as high as 0.11 for untreated banana epoxy composites and 0.12 for treated banana epoxy composites in the frequency ranges from 500 Hz to 6000 Hz.

Link: Nano Hybrids and Composites

Jayamani, E., Soon, K.H., and Bakri, M.K.B., "Effect of Implementing Digital Learning Technologies Podcasting and Blogs to Enhance Student Learning in Manufacturing Subjects", 7th Annual International Conference on Computer Science Education: Innovation & Technology (CSEIT 2016), pp. 144-149.

Abstract: This research was focused to implement Digital Learning Technologies (DLTs) such as podcasting and blogs in teaching and learning activities in manufacturing subject. Podcasting involves placing recorded material on a website from where it can be downloaded and listened to at a later time. Manufacturing subject contents contain many manufacturing concepts and methods, by means of lectures using conventional power point slides. Although students cannot understand many concepts of manufacturing, but by implementing podcasting students can understand all the concepts that is by bringing the real world of industrial videos in their hands through the iPhone, iPad and notebooks. Along with podcasting, blogs also used to enhance students’ learning. Students can use blogs to gather resources and share their materials and opinions with others. The main purpose of implementing blogs in manufacturing subject is to support the meaning of the subject teach, by making through reflective learning and the development through the exchange of hyperlinks of knowledge between communities. It can foster the development of learning identities and reduce feelings of isolation. The existing method using power point slides for teachings usually criticized and its method being discussed. Also, the pros and cons of the proposed method have been discussed in this research. Results from this study indicate that the educational institutions and academics need to contemplate the introduction of instructional methods such as podcast and blogs within the broader context of instructional goals.

Link: Global Science & Technology Forum (GSTF)

Jayamani, E., Soon, K.H., and Bakri, M.K.B., "Effect of Developing Analytic/Task Specific Rubric for an Enhanced Student Learning in Manufacturing Subjects", 7th Annual International Conference on Computer Science Education: Innovation & Technology (CSEIT 2016), pp. 31-37.

Abstract: This research focused on the development of analytic/task specific rubric for assessment items in Manufacturing subjects. Rubrics are evaluation tools that assisted the process based on an assessment and report on student achievement by educators. Prior to the design of specific rubric, educators can decide whether the performance or product will be scored holistically or analytically. Thus, this research generates analytic/task specific rubrics for assessment items such as lab reports, written reports and oral presentations on manufacturing subjects. The critique about the existing method of grading has been discussed and the pros and cons of the proposed method have been discussed in this research. Currently, the assessment items in the manufacturing subjects used a holistic/general rubric. It provides students with an overall evaluation of the performance or product that some of the detailed does not being provided and diagnostic with feedback such as strengths and weakness of the performance/product. It gives a quick snapshot of overall status or achievement, in example, the speed of scoring is more significant than knowing how to precisely describe quality. The main drawbacks of the holistic rubrics are not as good in identifying the weaknesses and strengths, and planning instruction, for example, two students can get the same score for vastly different reasons. To avoid these drawbacks, this research was proposed to develop analytic/task specific rubrics for assessment items in the manufacturing subjects. Analytic rubric provides several scores or ratings for a product or performance. It showed relative strengths and weaknesses assess the complicated skills, detailed feedback to students and parents, products, or performances that several dimensions are needed to be clear.

Link: Global Science & Technology Forum (GSTF)

Jayamani, E., Hamdan, S., Soon, K.H., Rahman, M.R., and Bakri, M.K.B., (2016), "Acoustical, Thermal, and Morphological Properties of Zein Reinforced Oil Palm Empty Fruit Bunch Fiber Bio-composites", Journal of Applied Polymer Science, 133(43), 1-8.

Abstract: In this research, biodegradable composites were prepared with zein as a polymer matrix and oil palm empty fruit bunch (OPEFB) as fiber reinforcement. The fibers were treated with sodium hydroxide (NaOH). The effects of sodium hydroxide treatment on sound absorption, thermal stability, and fiber-polymer matrix interaction in composites were examined. The acoustical sound absorption coefficients of the composites were evaluated using two-microphone transfer function impedance tube method. The spectral, thermal, and morphological studies of the composites were analyzed and characterized using scanning electron microscope (SEM), thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) spectroscopy. It was found that in all the biodegradable composites, the sound absorption coefficients increased as the frequency increased. Increases in fiber loading caused sound absorption coefficients of the composites to increase. The sodium hydroxide treatment showed a better interface adhesion on fiber and zein matrix. It was also found that this treatment increased the sound absorption coefficients. This was supported by qualitative analysis on the SEM micrographs and FTIR spectrum.

Link: Journal of Applied Polymer Science

Bakri, M.K.B., Jayamani, E., Hamdan, S., Rahman, M.R., Soon, K.H., and Kakar, A., (2016), "Fundamental Study on The Effect of Alkaline Treatment on Natural Fibers Structures and Behaviors", ARPN Journal of Engineering and Applied Sciences, 11(14), 8759-8763.

Abstract: In composites, chemical treatment caused better adhesion interface between fibers and polymer. Thus, in this research, alkaline treatment was performed on jute and kenaf fibers in an alkaline solution containing 5wt % sodium hydroxide diluted with distilled water, at room temperature for 30 minutes. The pH levels of the alkaline solution were maintained approximately at pH 11 to pH 12. The untreated and treated fibers were analyzed using Fourier transform infrared (FTIR) spectroscopy in the range of 4000 cm-1 to 400 cm-1. It is found out that change in the structure and the removal of outer cell layers, cellulose, hemi cellulose, lignin, waxes and other impurities during the alkaline treatment that affected the improvement on the adhesion interface between fibers and polymer.

Link: ARPN Journal of Engineering and Applied Sciences

Jayamani, E., Hamdan, S., Ezhumalai, P., and Bakri, M.K.B., (2016, )"Investigation on Dielectric and Sound Absorption Properties Of Banana Fibers Reinforced Epoxy Composites", Journal Teknologi, 78(6-10), 97-103.

Abstract: This research work focused on the development of banana fiber reinforced epoxy resin composites for dielectric and sound absorption applications. The dielectric and sound absorption properties of the composites were studied with respect to the fiber loading and treatment. The fibers were treated using 5wt % of sodium hydroxide at room temperature. The properties of the composites were measured using HP Impedance Analyzer E4980A and two-microphone transfer function impedance tube method according to the American Society for Testing Materials (ASTM D150-11 and ASTM E1050-12) standards. In general, the composites displayed higher dielectric constant and sound absorption coefficients at the higher fiber loading. In extend, the treated fibers reinforced composites showed higher sound absorption coefficients, but lower dielectric constant values.

Link: Jurnal Teknologi

Jayamani, E., Hamdan, S., Bakri, M.K.B., Soon, K.H., Rahman, M.R., and Kakar, A., (2016), "Analysis of Natural Fiber Polymer Composites: Effects of Alkaline Treatment on Sound Absorption", Journal of Reinforced Plastics and Composites, 35(9), 703-711.

Abstract: This study is focused on the development of sound absorbing materials based on natural fiber polymer composites. The natural fibers were modified through the alkaline treatment and the natural fiber polymer composites were fabricated using hot and cold compression hydraulic press machine. The sound absorption coefficients of the composites were measured using two-microphone transfer function impedance tube method. Characterizations of the natural fiber polymer composites were analyzed using scanning electron microscope and Fourier transform infrared spectroscopy. It was found that in all measured composites, the sound absorption coefficients increased as the frequency increased. Also, as the fiber loading increased, the sound absorption coefficients of the natural fiber polymer composites were increased. It was found that the alkaline treated fiber reinforced composites increased the sound absorption coefficients due to removal of impurities and change in the structure of composites. The alkaline treatment of fibers showed better adhesion interface between fiber and polymer as compared to untreated fibers. This can be seen clearly under morphological and spectral studies of the natural fiber polymer composites.

Link: Journal of Reinforced Plastics and Composites

Bakri, M.K.B., and Jayamani, E., (2016), "Comparative Study Of Functional Groups In Natural Fibers: Fourier Transform Infrared Analysis (FTIR)". Chauhan, P.S., (ed), In: Futuristic Trends in Engineering, Science, Humanities, and Technology, Vol 1, Chapter 30, TroIndia, 167-174

Abstract: Throughout this research, the fundamental characterization of functional groups bond structure and the behavior of natural fiber before and after treatment were understood. Fibers were obtained by extracting it from the bamboo, betel nut and hemp plants. The Infrared spectrum of natural fiber were obtained and tested using Fourier transform infrared (FTIR) spectroscopy in the range of 400 cm-1 to 4000 cm-1 for untreated and alkali treated fibers. It was prepared quantitatively and qualitatively according to ASTM E168-06 and ASTM E1252-98 standards. Based on the Infrared spectral, the functional groups of the plant fiber were then collected and classified. The effect of chemical treatment was evaluated and discussed. Based on the result obtained, the bond structure of certain functional groups (i.e. hemicellulose, cellulose, and lignin) was removed and changed due to the alkaline treatment.

Link: TroIndia

Jayamani, E., Hamdan, S., Rahman, M.R., and Bakri, M.K.B., (2015), "Dielectric Properties of Lignocellulosic Fibers Reinforced Polymer Composites: Effect of Fiber Loading and Alkaline Treatment", Materials Today: Proceedings, 2(4-5), 2757-2766.

Abstract: This research work focus on comparative studies of dielectric properties such as the dielectric constant, the dissipation and loss factor of four different types of composites made of lignocellulosic fibers with respect of fiber loading and alkali treatment. It has been observed that the dielectric constant, dissipation factor and loss factor progressively increases with increase in fiber loading and decreases with an increase in frequency. The dielectric properties of sisal/poly-lactic acid composites show higher values compared with other composites. This is due to the characteristics of lignocellulosic contents in the sisal fibers. The dielectric constant values were lower for fibers subjected to alkaline treatment.

Link: Materials Today: Proceedings

Bakri, M.K.B., Jayamani, E., Soon, K.H., Hamdan, S., (2015),"Reinforced Oil Palm Fiber Epoxy Composites: An Investigation on Chemical Treatment of Fibers on Acoustical, Morphological, Mechanical and Spectral Properties", Materials Today: Proceedings, 2(4-5), 2747-2756

Abstract: Oil palm fibers are plentifully unused waste types of cellulose fibers. It is extensively being wasted in modern agriculture and industries because of the limited research and knowledge on the use and functionality of oil palm fibers in certain sectors and products. Throughout this research, studies and examinations conducted to investigate the developments of reinforced untreated and treated oil palm fiber epoxy composites. Then, the effects of alkaline treatment on the fiber structure being analyzed. Lastly, based on the results obtained, the effects on the acoustical, morphological, mechanical, and spectral properties being investigated according to specific tests and standards.

Link: Materials Today: Proceedings

Jayamani, E., Hamdan, S., Rahman, M.R., Kakar, A., and Bakri, M.K.B., (2015), "An Investigation of Sound Absorption Coefficient on Sisal Fiber Poly Lactic Acid Bio-Composites", Journal of Applied Polymer Science, 132(34), 1-8.

Abstract: In this research, the mechanical, acoustical, thermal, morphological, and infrared spectral properties of untreated, heat and alkaline-treated sisal fiber-reinforced poly-lactic-acid bio-composites were analyzed. The bio-composite samples were fabricated using a hot press molding machine. The properties mentioned above were evaluated and compared with heat-treated and alkaline-treated sisal fibers. Composites with heat-treated sisal fibers were found to exhibit the best mechanical properties. Thermo-gravimetric analysis (TGA) was conducted to study the thermal degradation of the bio-composite samples. It was discovered that the PLA-sisal composites with optimal heat-treated at 160°C and alkaline-treated fibers possess good thermal stability as compared with untreated fiber. The results indicated that the composites prepared with 30wt % of sisal had the highest sound absorption as compared with other composites. Evidence of the successful reaction of sodium hydroxide and heat treatment of the sisal fibers was provided by the infrared spectrum and implied by decreased bands at certain wavenumbers. Observations based on scanning electron microscopy of the fracture surface of the composites showed the effect of alkaline and heat treatment on the fiber surface and improved fiber-matrix adhesion.

Link: Journal of Applied Polymer Science

Jayamani, E., Hamdan, S., Rahman, M.R., Soon, K.H., and Bakri, M.K.B., (2015), "Study of Sound Absorption Coefficients and Characterization of Rice Straw Stem Fibers Reinforced Polypropylene Composites", BioResources, 10(2), 3378-3392.

Abstract: In this study, both untreated rice straw stem fibers and fibers treated with sodium hydroxide were used. Maleic anhydride polypropylene (MAPP) was used to enhance adhesion of the fiber with the matrix. Composites were prepared with various combinations of fiber, ranging from 10 wt.% to 25 wt.%, and polypropylene in addition to 2 wt.% MAPP. These composites were then tested for acoustical, mechanical, thermal, infrared spectral, and morphological properties. The fibers were treated by being soaked in 5 wt.% NaOH solution at 30 °C for 30 min. The composites with treated fiber exhibited higher thermal stability, tensile strength, sound absorption, and fiber-matrix adhesion than the composites with untreated fiber. The results of sound absorption measurements showed that the composites with higher fiber content had better sound absorption than the composites with lower fiber content. The changes in the peaks in the Fourier transform infrared spectrum indicate that the alkaline treatment removed hemicellulose and lignin from the rice straw stem fibers.

Link: BioResources

Kakar, A., Jayamani, E., Soon, K.H., Bakri, M.K.B., Hamdan, S., (2015), "Optimization of Hot Press Compression Molding and Fabrication of Poly Lactic Acid (PLA) Luffa Biocomposites for Biomedical Applications ", Australian Journal of Basic and Applied Sciences, 9(8), 105-112.

Abstract: Biopolymer composites for tensile testing were fabricated according to the American Society for Testing Materials, ASTM D638-10, using poly lactic acid (PLA) as the matrix material and varying volume percentage of heat treated and untreated luffa fiber as the reinforcement material. To achieve the composite materials with the highest tensile strength, optimization of the use of hot press machine for fabrication of composite specimens was given high importance. While optimizing the use of hot press machine, various parameters were considered. These parameters included processing temperature, processing time and cooling time. Combinations of varying magnitudes of these parameters were used to find the optimum processing method. The optimized method was then used to produce PLA – luffa composites. The fiber – matrix interface adhesion was studied using scanning electron microscope (SEM). The results show that composites made with heat treated fibers have higher tensile strength and better interfacial adhesion when compared with the tensile strength of composites made with untreated fiber. Heat treated fibers showed a remarkable improvement in the tensile strength of the biocomposites, which may be used for a variety of applications in the orthopedic field.

Link: Australian Journal of Basic Applied Sciences

Jayamani, E., Hamdan, S., Rahman, M.R., and Bakri, M.K.B., (2014), "Investigation of Fiber Surface Treatment on Mechanical, Acoustical and Thermal Properties of Betelnut Fiber Polyester Composites", Procedia Engineering, 97(1), 545-554.

Abstract: This research work is concerned with the development of unsaturated polyester composites reinforced with betelnut fibers. Moreover, the fibers were chemically modified by sodium hydroxide and its effects on the fiber/matrix interaction were also evaluated. Raw and chemically modified fibers have been used in different proportions for the preparation of these composites. The optimization of fiber proportions has been done in term of their tensile strength. The sodium hydroxide treatment effect of fibers was verified by FTIR analysis and the fibers morphological aspects of fibers by SEM. Likewise, the sound absorption coefficient of composites were studied using impedance tube method. The thermal analyses of composites were made using Thermogravimetric analysis. Compared with untreated fiber composites, there was an improvement in the tensile strength of the treated fiber composites. SEM micrographs of betelnut fiber surface revealed the rough and perforated surface of fibers. Whereas, the cross sectional of the betelnut fibers showed the bigger lumen structures. The sound absorption coefficients of composites increased as the frequency increased and thicker composites appeared to perform better than those of thinner ones. The thermal stability of the treated fiber composites was found to be higher than that of untreated fiber composites.

Link: Procedia Engineering

Jayamani, E., Hamdan, S., Rahman, M.R., Soon, K.H., and Bakri, M.K.B., (2014), "Comparative Study of Dielectric Properties of Hybrid Natural Fiber Composites ", Procedia Engineering, 97(1), 536-544 .

Abstract: The dielectric properties, such as dielectric constant, dissipation factor and dielectric loss factor of jute/bamboo natural fibers reinforced with polypropylene and unsaturated polyester hybrid composites were studied with different fiber loadings, fiber ratios, frequencies and chemical modifications of natural fibers. The dielectric constant, dissipation factor and loss factor increased with an increase in the fiber content for the entire range of frequencies than the pure polypropylene and pure unsaturated polyester materials. This increase was high at low frequencies, low at medium frequencies, and very low at high frequencies. Dielectric constant values were observed to decrease in frequency due to the decreased interfacial and orientation polarization at higher frequencies. Whereas, dielectric constant increased with an increase in the fiber loading, due to the increase in the number of polar groups, after the addition of hydrophilic lignocellulose fibers. Sodium hydroxide treatment was carried out on jute and bamboo fibers to improve the adhesion between fibers and matrix. The dielectric constant was lower for composites consisting of fibers subjected to alkaline treatment due to the increased hydrophobicity of fibers. When the weight percentage of jute fiber was increased in the total fiber content of the hybrid composites, the dielectric constant, dissipation factor and loss factor were found to increase. It is evident that types of polymer have little influence on the dielectric properties of the hybrid composites.

Link: Procedia Engineering

Jayamani, E., Hamdan, S., Soon, K.H., Rahman, M.R., Bakri, M.K.B., and Kakar, A. (2014), "The Effect of Natural Fibres Mercerization on Natural Fibres/Polypropylene Composites: A Study of Thermal Stability, Morphology and Infrared Spectrum", Australian Journal of Basic and Applied Sciences, 8 (15), 332 - 340.

Abstract: This research was carried out to evaluate how alkali treatment of selected natural fibres (kenaf, luffa, betel nut, banana and rice straw) influences thermal properties, morphological properties and infrared spectrum properties of the composites made from polypropylene reinforced with natural fibres. Composites were made by compression moulding technique using hydraulic hot press. Composites were characterized by thermo-gravimetric analysis (TGA) to establish their thermal stability. The infrared spectrum of both treated and untreated natural fibres/PP composites were studied using Fourier transforms infrared spectrometer (FTIR). Infrared spectroscopy is sensitive to the presence of chemical functional groups in the composites. A functional group is a structural fragment within a molecule. Scanning electron microscopy (SEM) was used to investigate the morphology of composites. Increase in the thermal stability and better fibre-matrix compatibility of the composites were noticed in the treated fibres. Thermal stability of all the reinforced natural fibres was found to be around 205°C. Decomposition of both cellulose and hemicellulose in the fibres took place at 310°C and above, whereas the degradation of reinforced fibre composites took place above 430°C. After the chemical treatment, the FTIR results showed the reduction of OH bonds for all natural fibre composites used in this study. Mercerization had successfully modified the structure of natural fibres and these modifications improved the thermal stability of the composites by promoting better fibre-matrix bonding.

Link: Australian Journal of Basic and Applied Sciences