Page 321 - Handbook of Plastics Technologies

Source: Handbook of Plastics Technologies

CHAPTER 5

PLASTICS ADDITIVES

Rudolph D. Deanin
University of Massachusetts
Lowell, Massachusetts

There are about 100 families of commercial polymers in use in the plastics industry. Most
of these are available in a range of molecular weights, and many of them are also available
in a range of copolymers. This certainly provides a wide range of properties for use in dif-
ferent products.
But the many thousands of different plastic products require a much greater variety of
properties and balance of properties. It might be possible to develop a new polymer to
meet each of these needs, but the time and cost would be prohibitive. In most cases, it is
much more convenient to use the polymers that are commercially available and to improve
individual properties, and balance of properties, by the use of additives.
Thus, polymers are hardly ever used in pure form; they are almost always optimized by
the use of additives. In most cases, a few additives are sufficient. But in some polymer
families, compounders escalate to much larger numbers of additives so as to produce the
processability and final properties they need. The most extreme examples are in vinyls,
rubber, coatings, and adhesives, where the number of additives in a compound can easily
reach 10 to 20 or even more!
The total tonnage of additives is conventionally about 18 percent of plastics produc-
tion. If we include polymers added in making polymer blends, the total increases to about
25 percent. The major families of additives may be listed in order of total tonnage as fol-
lows:
• Fillers and reinforcements
• Polymers for polymer blends
• Plasticizers
• Flame Retardants
• Colorants
• Stabilizers (antioxidants, antiozonants, vinyl heat stabilizers, UV, and biostabilizers)
• Lubricants
• Organic peroxides
• Foaming agents
• Antistats

5.1
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