重合 化學(xué)特性,用途語,生産方法
解説
天然の高分子物質(zhì)のうちセルロース、ゴムなどや、合成高分子物質(zhì)のすべては小さい化學(xué)的集団の単位（単位化合物）の繰り返しによってできている。この単位化合物を単量體（モノマーmonomer）とよび、この単量體が統(tǒng)計の法則に従って多數(shù)個結(jié)合して高分子物質(zhì)をつくっている。このときできあがった高分子を重合體（ポリマーpolymer）といい、また重合體を構(gòu)成している?yún)g量體の數(shù)を重合度ともよんでいる。重合とは、この重合體をつくりあげる化學(xué)反応を総稱している。なお、2種類以上の単量體が重合することを共重合といい、重合體が単量體に分解することを解重合という。
定義
The process in which one or more compounds
react to form a POLYMER. Homopolymers
are formed by polymerization
of one monomer (e.g. the formation of
polyethene from ethene). Heteropolymers
or copolymers come from two or more
monomers (e.g. the production of NYLON).
Heteropolymers may be of different types
depending on the arrangement of units. An
alternating copolymer of two units A and B
has an arrangement:
–A–B–A–B–A–B–
A block copolymer has an arrangement in
which blocks of one monomer alternate
with blocks of the other; for example:
–A–A–A–B–B–B–A–A–A–
In a graft copolymer there is a main choice
of one monomer (–A–A–A–A–), with short
side chains of the other monomer attached
at regular intervals (–B–B–).
Stereospecific polymers have the subunit
repeated along the chain in a regular
way. These are tactic polymers. If one particular
group is always on the same side of
the chain, the polymer is said to be isotactic.
If the group alternates in position along
the chain the polymer is syndiotactic. If
there is no regular pattern, the polymer is
atactic.
Polymerization reactions are also classified
according to the type of reaction. Addition
polymerization occurs when the
monomers undergo addition reactions,
with no other substance formed. Condensation
polymerization involves the elimination
of small molecules in formation of the
polymer.
工業(yè)用途
Polymerization is the linking of small molecules(monomers) to make larger molecules.Polymerization requires that each small moleculehave at least two reaction points or functionalgroups. There are two distinct majortypes of polymerization processes: condensationpolymerization, in which the chain growthis accompanied by elimination of small moleculessuch as water (H
2O) or methanol(CH
3OH); and addition polymerization, inwhich the polymer is formed without the lossof other materials.
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