Synthesis mechanism of modified nylon
Release time:
2024-07-02
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Modified nylon synthesis process is an anionic type of catalytic polymerisation reaction, the reaction process is as follows: 1, the formation of lactam anion: in the metal sodium, sodium hydroxide and other alkaline catalysts, caprolactam monomer to generate caprolactam sodium salt, in the alkaline reaction system, the dissociation of the active lactam anion.
Modified nylon synthesis process is an anionic type of catalytic polymerisation reaction, the reaction process is as follows:
1, the formation of lactam anion: in the metal sodium, sodium hydroxide and other alkaline catalysts, caprolactam monomer to generate caprolactam sodium salt, in the alkaline reaction system, the dissociation of the active lactam anion.
2, chain growth process: the lactam anion further nucleophilic addition reaction with the monomer and ring-opening, the formation of active amine anion dimer, the active dimer rapid proton exchange with the monomer, resulting in the generation of acyl dimer, while the lactam anion regeneration.
Acylated dimer with imide structure, has a strong electrophilic property, and becomes the initiation centre of the chain. Therefore, the anionic activity is the determining factor for the rate of chain growth reaction.
3、Equilibrium reaction and crystallisation process: the polymerisation reaction of modified nylon is carried out below the melting point of the polymer, and the late stage of polymerisation is characterised by rapid molecular weight growth accompanied by polymer crystallisation and solidification. People usually add compounds with imide structure as activators directly in the reaction, so that the whole polymerisation reaction can be completed quickly at low temperature (120-150℃).
At the same time, different crystalline morphology MC can be formed during the polymerisation by changing the polymerisation monomer, catalyst type or adding co-catalysts and enhancement modifiers with different structures, so as to obtain modified nylon products with different properties.
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