Plastics

• Plastics — polymers; mouldable synthetic materials.
• Thermoplastics (soften on heating — polyethylene, PVC) vs thermosetting (bakelite, melamine — don't soften).
• Non-biodegradable — environmental problem.
• Reduce, reuse, recycle; use jute/cloth bags.

1. Polymer — long chain of repeating units; plastics are synthetic polymers.
2. Thermoplastics — can be remoulded (bottles, bags, toys).
3. Thermosetting — permanent shape once set (switches, handles, floor tiles).
4. Properties — light, poor conductor of heat/electricity, resistant to chemicals.
5. Environmental issues — landfill, ocean pollution, harm to animals.
6. Real world — ban on single-use plastic bags; recycling codes on bottles; paper straw alternatives.

Classifying household plastic items

Thermoplastic: water bottle (PET), carry bag (LDPE) — can remelt.
Thermosetting: electric switch plate (bakelite) — charred if overheated, does not melt.
Step — heat test only by teacher demo; don't try at home unsafely.

• Throwing all plastic as biodegradable (most persist for centuries).
• Misconception: burning plastic is safe disposal (toxic gases).
• Confusing thermoplastic with thermosetting behaviour.
• Using PVC for food wrap without checking food-grade.

• Difference between thermoplastics and thermosetting plastics.
• Why are plastics a environmental concern?
• Give two examples of each plastic type.

Open the Practice tab for graded questions on Plastics.