TABLE OF CONTENTS Standardized acronyms for polystyrenes and their derivatives are:
PS for polystyrene
SB for butadiene rubber-modified polystyrene or HIPS (high-impact polystyrene)
SMA for styrene maleic anhydride.
From the simple chemical formulae of styrene and its polymer
are born several subfamilies according to the polymerization process, use of comonomers, blending with elastomers, and the use of reinforcements:
Homopolymers, by polymerization of polystyrene alone. These homopolymers are rigid, brittle and transparent.
Copolymers, by polymerization of polystyrene with:
a rubber, the most commonly used being butadiene, to improve impact strength and behaviour at low temperature but altering rigidity
maleic anhydride to improve thermal performances
another comonomer such as acrylonitrile to improve mechanical or chemical performances.
Alloys
with elastomers such as polybutadiene, which confers very high impact strengths even at low temperature but alters transparency
with other plastics to bridge the gap between the respective sets of properties for each of the used plastics.
Combination of copolymerization and blending with rubbers, for example ABS
Reinforcement: glass fibres are used to increase rigidity at ambient and higher temperatures, as well as to decrease creep.
The main polymerization techniques are a bulk process, which is a continuous process, and a suspension method, which is discontinuous.
A metallocene-catalysed polymerization was used to produce syndiotactic polystyrene but its marketing was recently suspended.
This section deals with atactic polystyrene homopolymer, and high-impact polystyrene.
The properties of SMA are included in Table 4.36 and are not otherwise detailed.
For the homopolymer...
