1. What changes does heating the plastic cause in its interior that make it not reusable like metal?
2. If the oil runs out, there are already many plans for energy, but what about the raw materials of these polymer chemical products? Are there alternative products?

No best answer

Plastics are generally divided into two types: thermoplastic and thermosetting. Ordinary thermoplastics can be melted and reshaped, but this process will cause a certain degree of (polymer chain) degradation and reduce performance. Thermosetting plastics are relatively difficult. The most thorough method is of course to degrade the plastics into monomers and then synthesize them again. However, this requires high technology (especially catalysts) and cost, and industrialization is still difficult at this stage. In addition, there are many plastics that are a variety of plastics and alloys, or composite materials added with other inorganic substances, or various additives are added for performance or function requirements, and it is difficult to reuse them.