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The product is polystyrene. As alkenes can polymerize in somewhat straightforward radical reactions, they form useful compounds such as polyethylene and polyvinyl chloride (PVC), [3] which are produced in high tonnages each year [3] due to their usefulness in manufacturing processes of commercial products, such as piping, insulation and packaging.
The easiest way to visualize the mechanism of a step-growth polymerization is a group of people reaching out to hold their hands to form a human chain—each person has two hands (= reactive sites). There also is the possibility to have more than two reactive sites on a monomer: In this case branched polymers production take place.
Polystyrene foam blows in the wind and floats on water due to its low specific gravity. It can have serious effects on the health of birds and marine animals that swallow significant quantities. [71] Juvenile rainbow trout exposed to polystyrene fragments show toxic effects in the form of substantial histomorphometrical changes. [72]
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 ...
Note that different copolymer sequencing is sufficient to define a structural difference, thus an A-B diblock copolymer with A-B alternating copolymer side chains is properly called a graft copolymer. For example, polystyrene chains may be grafted onto polybutadiene, a synthetic rubber which retains one reactive C=C double bond per repeat unit.
Free radical polymerization has found applications including the manufacture of polystyrene, thermoplastic block copolymer elastomers, [29] cardiovascular stents, [30] chemical surfactants [31] and lubricants. Block copolymers are used for a wide variety of applications including adhesives, footwear and toys.
Maleic acid in fact does not homopolymerize in free radical polymerization, but will form an almost exclusively alternating copolymer with styrene. [8] >> >> In the initial stage of the copolymerization, monomer 1 is incorporated faster and the copolymer is rich in monomer 1. When this monomer gets depleted, more monomer 2 segments are added.
Polymer blends can be broadly divided into three categories: immiscible polymer blends (heterogeneous polymer blends): This is by far the most populous group. If the blend is made of two polymers, two glass transition temperatures will be observed.