"It's made of plastic" is a common put-down. Marketers selling higher-end bits made of plastic (like gun parts) try to evade the stigma by calling it "polymer", but that's just a stupid euphemism: every plastic is a polymer, though not every polymer is a plastic.
Plastics vary widely in their characters. Polyethylene and polypropylene are the cheapest and most common plastics, made of just hydrogen and carbon atoms. They are chemically unreactive, good for containers, but weak when exposed to UV light. Nylon is strong, used for nuts and bolts, fishing line, and women's hosiery. Nylon with 30% glass fiber reinforcement is as strong as cast aluminum and used in guns and power tool housings.
Polycarbonate is used for bulletproof windows and safety glasses, but is vulnerable to chemical attack from acetone. It also releases bisphenol A (BPA). PVC is rigid in its natural form for house siding and sewage pipes, but can be made flexible with plasticizers for inflatable boats and shower curtains. However, PVC contains toxic stabilizers with lead and releases harmful chlorine compounds when burned.
Source: Hacker News · Summarized by HeadlinesBriefing