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The term, thermoplastics mean that once the polymer is formed, it can be heated and reformed over and over again. The molecules are held together by weak secondary bonding forces that causes the plastic to soften when exposed to light and return back to its original shape, when cooled back down to room temperature. The structure associated with thermoplastics is that of individual molecules that are separate from one another and flow past one another.

The molecules may have low or extremely high molecular weight, and they may be branched or linear in structure, but the essential feature is that of separability and consequent mobility. It should also be noted that these substances also have little cross-linking. Since extrusion, molding or pressing when exposed to heat can shape thermoplastics; it therefore offers versatility and a large range of applications.

This property of plastics allows for easy processing and facilitates recycling; the majority of polymers are therefore thermoplastics.

Polyethylene: packaging, electrical insulation, milk and water bottles, packaging film, house wrap, agricultural film

Polypropylene: carpet fibers, car bumpers, microwave containers

Polyvinyl chloride (PVC): floor and wall coverings, siding, credit cards, car instrument panels.

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