The working properties, stock forms, sizes and extrusions, common uses and environmental impact of the following: 

– thermoplastics ○ acrylic (PMMA) ○ nylon ○ polyvinyl chloride (PVC) ○ polystyrene (PS) ○ polypropylene (PP) ○ high and low density polyethylene (HDPE) (LDPE) ○ high impact polystyrene (HIPS) ○ polycarbonate (PC) ○ acrylonitrile butadiene styrene (ABS) ○ polyethylene terephthalate (PET) 

– thermosetting plastics ○ polyester resin ○ melamine formaldehyde (MF) ○ urea formaldehyde (UF) ○ epoxy resin – elastomers ○ neoprene ○ silicone ○ thermoplastic elastomer (TPE).

Polymers are made up of long chain molecules containing carbon, hydrogen and oxygen atoms, along with other chemicals such as chlorine and fluorine.

Polymers occur naturally in nature and can be derived from plant and animal sources.

They include:

• Casein (derived from milk) which is still used to make buttons, 

• Horn, 

• Resin (from trees) 

• Cellulose from plants - In the case of Cellulose it is mixed with acetic acid to make Cellulose acetate which is still used today for OHP slides.

These could be classed as natural polymers as they possess a similar molecular structure to those polymers commercially used today.

Synthetic polymers are gained through a process of thermal cracking. As they are derived from fossil fuels (particularly oil) they are carbon based and account for the majority of plastics used today.

In order for it to be useful to us, crude oil is broken down in oil refineries into its component parts, known as fractions, and these can then be used for many different purposes.

Fractions that are produced by the distillation of crude oil can go through a process called cracking. This chemical reaction produces smaller hydrocarbons, including alkanes and alkenes.

Ethene and other alkenes are unsaturated hydrocarbons and can be used to make polymers. Ethene can be used to make ethanol.

Polymers have some unique properties which make them particularly useful for modern day applications.

• They are good electrical and thermal insulators

• They have a good strength to weight ratio. This does not mean they are strong in the same way as steel but that they have good strength compared to their weight.

• They generally have good atmospheric and chemical resistance.

• They have fairly low melting temperatures (Thermoplastics only)

• They are lightweight

• They can be self coloured, opaque or transparent and are self finishing.

• They are quite hygienic and are water resistant.

• They can be enhanced with the addition of fillers, plasticisers and stabilisers to make them more flame retardant or anti static etc.

Thermoplastic Elastomers (TPE’s) can be processed using conventional moulding equipment i.e. injection moulding and have the advantage of quicker production times compared to natural or synthetic rubbers.

Another advantage is that all waste and scrap material can be recycled.

TPE’s are commonly used for wire and cable coatings, for seals and hoses in the automotive industry as well as over mouldings of grips onto power tools casings, toothbrushes, pens and utensils etc...

Neoprene, a synthetic rubber known for its durability and insulation, has become a staple in various industries. Its unique properties make it ideal for applications requiring flexibility, water resistance, and temperature stability. However, the production and disposal of neoprene raise environmental concerns due to its reliance on petroleum-based resources and its non-biodegradable nature.

Positives:

• Excellent flexibility: Neoprene can bend and stretch without losing its shape or integrity.

• Water resistance: It effectively repels water, making it suitable for aquatic environments.

• Insulation: Provides thermal insulation, keeping the wearer warm in cold conditions.

• Durability: Resistant to abrasion, chemicals, and ozone, ensuring a long lifespan.

Negatives:

• Environmental impact: Made from petroleum, a non-renewable resource, and does not biodegrade.

• Potential for off-gassing: Can release volatile organic compounds (VOCs) during manufacturing and use.

• Cost: Generally more expensive than other types of rubber.

Common uses:

• Wetsuits: Provides thermal insulation and buoyancy for water sports enthusiasts.

• Protective gear: Used in gloves, padding, and supports for impact absorption and protection.

• Industrial applications: Seals, gaskets, and hoses in various industries due to its chemical resistance.

Environmental impact:

Neoprene's production relies on fossil fuels, contributing to greenhouse gas emissions and climate change. Its non-biodegradable nature leads to long-term waste accumulation in landfills. Additionally, the manufacturing process can release harmful chemicals into the environment. However, efforts are being made to develop more sustainable alternatives,1 such as plant-based neoprene, to mitigate these environmental concerns.