8.3 Linear Polymers

A linear polymer consists of a long chain of skeletal atoms to which are attached the substituent groups. Polyethylene （1） is one of the simplest examples. Linear polymers are usually soluble in some solvent，and in the solid state at normal temperatures they exist as elastomers，flexible materials，or glasslike thermoplastics. In addition to polyethylene，typical linear-type polymers include poly（vinyl chloride） or PVC（2），poly（methyl methacrylate） （also known as PMMA，Lucite，Plexiglass or Perspex）（3），polyacrylonitrile （Orlon or Creslan）（4），and nylon 66（5）.