THERMOPLASTICS

Its Properties and Applications

SKMM 2713 Manufacturing Process

By Kenneth Chaw (A13KM0053)

THERMOPLASTICS• A type of polymers

• Branched chain polymer – obtained by addition or condensation polymerization

• Can be heated and formed & reheat and reform repeatedly - Recyclable

• Heating – Softened & Melted

• Cooling – Shape formed & Solidified.

• Shape of polymer molecules :1) Linear 2) Branched

Advantages & Disadvantages of using Thermoplastics

Advantage DisadvantageProcessing is easy to be monitored – only a physical transformation

Temperature rise causes the modulus retention decreases

Do not release gases or water vapour when drying

Creep and relaxation behavior is poorer than thermosetting plastics

The wastes are partially reusable

Start deformation when exposed to organic solvents

General Characteristics• Ductile

• High fracture energy

• More easily repaired than thermosets

• Good environmental resistance

• High melt viscosities

• No chemistry during fabrication

• Potential for recycling

• Indefinite shelf life

• Anisotropic 

Partially Crystallin

eNearly linear

polymer structure

Tend to be flexible and folded up to form crystal

areas

High shrinkage : opaque, good

chemical resistance, low

friction good wear resistance

Amorphous

Bulkier molecular polymer structure

Tend to be stiffer, will not fold up to

form crystals

Low shrinkage : good

transparency, high friction, low wear

and chemical resistance

Classifications of Thermoplastics

Properties and Application Table of Thermoplastics

Thermoplastic Properties ApplicationsPolypropylene (PP) Good chemical resistance Packaging, Containers

Polyethylene (PE – LDPE & HDPE)

Good chemical resistance, flexible or semi rigid. Weatherproof, good low temperature performance, non toxic and low cost.

Low Density – Packaging and containersHigh Density – Kitchenware, chemical drums

Nylon/ Polyamide (PA) Rigid, tough, hardwearing Gears, automotive- bonet part, power tool housing.

Acetal (POM) Springlike, good wear, Aerosol valves, clock parts, computer printer components

Polyvinyl Chloride (PVC) Rigid or flexible grades, weatherprooof, non-flammable, good impact strength and electrical insulation

Drainpipes and guttering, cable insulation, flooring, roofing, hosepipes

Crystalline materials

Thermoplastic Properties ApplicationsPolycarbonate (PC) Transparent, Rigid, good

weather resistance and dimensional stability

Crash helmet visors, car head lamp lenses, safety helmets, babies bottles.

Acrylic (PMMA) Rigid, clear, glossy, good weather resistance

Lenses, signs, light diffusers, point of purchase displays

Acrylonitrile Butadiene Styrene (ABS)

Rigid, opaque, tough, good gloss, texture possible, high impact strength

Computer casing, car chasis (automotive industry)

Polystyrene (PS) Brittle, transparent, poor UV stability

Toys, packaging, cosmetic packaging, refrigerator linings

Properties and Application Table of ThermoplasticsAmorphous materials