Some Industrially Important Polymers - Fundamentals of Industrial Chemistry: Pharmaceuticals, Polymers, and Business - page 116

The ability to absorb a plasticizer is important for PVC. Porosity of the
PVC particle is an important quality parameter of PVC and is determined by
the polymerization process. Another characteristic of PVC that is determined
by the polymerization is particle size, with emulsion processes giving smaller
particles than suspension processes.

8.4 OTHER OLEFIN POLYMERS

There are many other commercially important olefin polymers based upon
polymerization of available substituted olefins.

H X

H X

CC

CC

Y m

H Y

H

For example, when X is hydrogen and Y is phenyl, we have the poly-
merization of styrene. Styrene can be polymerized by a variety of processes
including cationic, anionic, and organometallic. Metallocene catalysts have
been used to prepare syndiotactic polystyrene which is crystalline and has
improved heat capability. Most commercial polystyrene is made by a radical
polymerization process and is atactic. It is a low cost polymer and is useful for
its clarity, stiffness, and ability to be foamed. As a homopolymer, sometimes
referred to as general purpose (GP) polystyrene, it lacks toughness. It is
used for CD and DVD cases, disposable clear drinking cups, and plastic
utensils. It can be expanded or foamed to make disposable coffee cups,
inexpensive coolers, and insulation. Dow trademarked this as styrofoam ® .
The problem with toughness is solved by the addition of rubber particles
such as polybutadiene to make high impact polystyrene (HIPS). The rubber
particles can be dispersed in styrene and the styrene then polymerized. This
method grafts some of the polybutadiene to the styrene [9, 10].
One common terpolymer containing styrene is acrylonitrile-butadiene-
styrene, known as ABS. The acrylonitrile imparts heat stability and solvent
resistance. The butadiene imparts impact strength and the styrene imparts
stiffness, also known as high modulus, and good processability.
When X is hydrogen and Y is a carboalkoxy group, we polymerize to make
acrylates. If X is methyl and Y is carbomethoxy, we have methyl methacrylate
polymers. These are more commonly known by their tradenames: Perspex ® ,
ICI; Plexiglas, Rohm & Haas; and Lucite, Dupont.

H CH 3

CO 2 CH 3

CH 3
CO 2 CH 3 m
Polymethyl methacrylate

H

CC CC

H H