there is two groups of plastics. we can group other plastics into these groups. What are the two groups called?
Some plastics are partially crystalline and partially amorphous in molecular structure, giving them both a melting point (the temperature at which the attractive intermolecular forces are overcome) and one or more glass transitions (temperatures above which the extent of localized molecular flexibility is substantially increased). So-called semi-crystalline plastics include polyethylene, polypropylene, poly (vinyl chloride), polyamides (nylons), polyesters and some polyurethanes. Many plastics are completely amorphous, such as polystyrene and its copolymers, poly (methyl methacrylate), and all thermosets.
The other group is called thermosets, or thermosetting plastics. Thermoplastics can be remolded when heated sufficiently, while thermosets will burn if heated too much. .
polymer type, Haldia, Gail, Reliance.
