Polymers and Viscosity Demystified

What is a Polymer?

A polymer is actually the result of organic blocks called monomers linked together by way of a solvent.Depending on the mix and proportions of crude materials and diverse response conditions, numerous types of polymers could be created, for example, polystyrene, polycarbonate, polyethylene and PMMA. Composition of principle crude materials and added substances also result in polymers of different grades. SMM (Polymer) is presently producing 6 distinctive PMMA grades: MH, EX, EXN, MG, LG and LG2.

 

What is Viscosity?

Viscosity is a property of a fluid that provides resistance to its flow. Viscosity is as a result of internal friction of molecules and mainly depends upon the type & temperature of the liquid. 
The polymerisation reaction is conducted within specific conditions and boundaries. The grade of the PMMA polymer thus developed could be evaluated by viscosity, which will be asignificant characteristic for all materials, especially polymers. For liquids, viscosity determines flow characteristics, heat transfer and mass transfer. For polymers, viscosity is usually a measuring stick. Viscosity data is crucial as it helps in predictingbehavioural properties of the polymer. Also, measurement of viscosity is very important in monitoring the SMM (Polymer) process.

 

Determining Viscosity

How will you determine the viscosity of a solid cube of polymer? 
Polymer viscosities can vary from 103 to 107 Poise so one testing method cannot cover them all. So, two common testing methods are used: melt and solution.

Melt Viscosity

The melt index is a common testing technique that studies parameters like compression weight and testing temperature, predominantlyin higher viscosity polymers. Needless to say, the results depend on the sort of polymer. For instance, for the melt viscosity test of polyethylene, the study parameters incorporate a temperature of 190˚ C and weight of 10 kg. After having a certain time (say 10 minutes), the extruded polymer is weighed. The melt index is then expressed as grams of polymer/10 minutes and this value corresponds to the common molecular weight of the polymer. Polyethylene has an average molecular weight of 150,000 g/mole and a melt index near 0.3 / 10 minutes. 
For processes or final products where simple processing is needed, melt indices above 15 g/ 10 minutes are desirable.Where mechanical properties are required, melt indices below 1 g/10 minutes are preferred.

Solution Viscosity

Solution viscosity testing involves dissolving the polymer in a solvent, usually combined with gentle heat. The clear answer is then allowed to visit through an apparatus like a pipette and the travel is timed. The full time for the pure solvent to flow through the same apparatus is also calculated. These two values are then compared, resulting in a relative viscosity – which will be essentially the ratio of the polymer viscosity to the solvent viscosity.

While melt viscositytechnique is carried out by SMM(P) in regular frequency to ensure the polymer formed is well in order, solution viscosity is executed by SCASS during product certification stage as your final confirmation.

Sumitomo Chemical Singapore is certainly one of leading producers of the polymer - PMMA (Polymethyl Methacrylate), a polymer of MMA (Methyl Metacrylate Monomer).Visit us to learn more about polymers, PMMA and MMA. 

for more information kindly contact pmma suppliers

Comments