Which of the following plastics do not have cross-links between their polymer chains?
A. Nylon
B. Melamine
C. Polyvinyl Chloride
D. Bakelite
A and C
Plastics are classified based on the type of arrangement of monomer units. In some cases, the arrangement is linear, whereas in others it is cross-linked.
Nylon and polyvinyl chloride are linear chain polymers (thermoplastics) while melamine and bakelite are cross-linked polymers (thermosetting plastics).