How were ancient plastics made?

The main component of plastic is synthetic resin, which determines the properties of plastic, but synthetic resin is not the same as plastic, but a primitive "polymer". To become a cheap plastic, the following substances should be added to the synthetic resin: filler to improve the strength of plastic, plasticizer to increase the plasticity and softness of plastic, stabilizer to prevent the decomposition of synthetic resin, colorant to make the plastic colorful, lubricant to smooth the plastic surface, and antioxidant to prevent the plastic from oxidative cracking. These substances are mixed and processed into plastic.

The main component of plastic is resin. Resin refers to a polymer compound without various additives. The word resin was originally named after the lipids secreted by animals and plants, such as rosin and shellac. Resin accounts for about 40%~ 100% of the total weight of plastics. The basic properties of plastics mainly depend on the properties of resin, but additives also play an important role. Some plastics are basically composed of synthetic resin with little or no additives, such as plexiglass.