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Different types of polymers: 1) homopolymer 2) alternating copolymer 3) random copolymer 4) block copolymer 5) graft copolymer. In polymer chemistry, a copolymer is a polymer derived from more than one species of monomer. The polymerization of monomers into copolymers is called copolymerization.
Polystyrene is commonly injection molded, vacuum formed, or extruded, while expanded polystyrene is either extruded or molded in a special process. Polystyrene copolymers are also produced; these contain one or more other monomers in addition to styrene.
In one copolymer, the monomers can be almost perfectly alternating. [1] but (random) copolymerisation with less than 50% maleic anhydride content is also possible. [2] The polymer is formed by a radical polymerization, using an organic peroxide as the initiator. The main characteristics of SMA copolymer are its transparent appearance, high heat ...
[1] [2] [3] There are many forms of polymerization [4] and different systems exist to categorize them. IUPAC definition for polymerization In chemical compounds , polymerization can occur via a variety of reaction mechanisms that vary in complexity due to the functional groups present in the reactants [ 3 ] and their inherent steric effects .
For the copolymerization of a given pair of monomers, the two experimental reactivity ratios r 1 and r 2 permit the evaluation of (Q 1 /Q 2) and (e 1 – e 2). Values for each monomer can then be assigned relative to a reference monomer, usually chosen as styrene with the arbitrary values Q = 1.0 and e = –0.8.
A monomer with functionality 3 has 3 functional groups which participate in the polymerization. This will introduce branching in a polymer and may ultimately form a cross-linked macrostructure. The point at which this three-dimensional 3D network is formed is known as the gel point , signaled by an abrupt change in viscosity.
The use of the term polymer alloy for a polymer blend is discouraged, as the former term includes multiphase copolymers but excludes incompatible polymer blends. [3] Examples of miscible polymer blends: homopolymer–homopolymer: polyphenylene oxide (PPO) – polystyrene (PS): noryl developed by General Electric Plastics in 1966 (now owned by ...
Styrene acrylonitrile resin (SAN) is a copolymer plastic consisting of styrene and acrylonitrile. It is widely used in place of polystyrene owing to its greater thermal resistance. The chains of between 70 and 80% by weight styrene and 20 to 30% acrylonitrile. [1]