Preparation and Performance Analysis of POM Using Heteropolyacids as Catalyst
In order to solve the problem of polymerization efficiency and controllability of polyoxymethylene(POM)initiated by catalyst,the effects of catalyst and solvent types,catalyst addition amount,polymerization temperature,and other conditions on reaction rate and conversion rate were studied through polymerization experiments.The results show that the polymers prepared by different polymerization systems have differences in appearance,mechanical properties,thermal stability,processing stability and other aspects.The boron trifluoride system has a low initiation rate and requires a high concentration(20 mg/kg)to achieve catalytic polymerization.Compared with the boron trifluoride catalytic system,heteropoly,acid induction efficiency is higher,the polymerization induction period and curing time are relatively short.When the optimal concentration is 5 mg/kg,the conversion rate of the polymerization experiment is 78.2%,and the synthesized POM has better thermal stability and low content of unstable terminal groups.Besides,less formaldehyde is released and the EGM value is 72 mg/kg as well as the VDA275 value is 15 mg/kg.Therefore,heteropoly acid catalytic polymerization of POM is a more effective choice.
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