文档介绍：Source: Handbook of Plastics, Elastomers, posites
Chapter
1
Thermoplastics
Anne-Marie M. Baker
Joey Mead
Plastics Engineering Department
University of Massachusetts Lowell
Lowell, Massachusetts
Introduction
Plastics are an important part of everyday life; products made from plastics range from so-
phisticated articles, such as prosthetic hip and knee joints, to disposable food utensils. One
of the reasons for the great popularity of plastics in a wide variety of industrial applica-
tions is the tremendous range of properties exhibited by plastics and their ease of process-
ing. Plastic properties can be tailored to meet specific needs by varying the atomic
composition of the repeat structure; and by varying molecular weight and molecular
weight distribution. The flexibility can also be varied through the presence of side chain
branching and according to the lengths and polarities of the side chains. The degree of
crystallinity can be controlled through the amount of orientation imparted to the plastic
during processing, through copolymerization, by blending with other plastics, and via the
incorporation of an enormous range of additives (fillers, fibers, plasticizers, stabilizers).
Given all of the avenues available to pursue in tailoring any given polymer, it is not sur-
prising that the variety of choices available to us today exists.
Polymeric materials have been used since early times, even though their exact nature
was unknown. In the 1400s, Christopher Columbus found natives of Haiti playing with
balls made from material obtained from a tree. This was natural rubber, which became an
important product after Charles Goodyear discovered that the addition of sulfur dramati-
cally improved the properties; however, the use of polymeric materials was still limited to
natural-based materials. The first true synthetic polymers were prepared in the early 1900s
using phenol and formaldehyde to form resins—Baekelan