Control of the addition amounts of dioxolane and methyl acetal in polyoxymethylene production
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At present, polyoxymethylene in China is mostly produced by combining three materials—pentanedioic anhydride, trioxymethane, and methyl acetal—under the catalysis of boron trifluoride. There is a claim that by adjusting the amount of dioxolane added, polyoxymethylene with different strengths and toughness can be produced, and that by measuring the amount of methyl acetal added, the melt index of polyoxymethylene can be adjusted. Are these two claims correct? Aren’t the changes in the strength and toughness of polymer materials adjusted through polymer modification? Can polyoxymethylene with different strengths and toughness also be produced by adjusting the amounts of the polymerization reactants?
Both statements are correct. 1. Methyl acetal, as a regulator, can control the molecular weight and thereby regulate the melt index ； 2. As a copolymer monomer, the amount of dioxolane used and its distribution within the molecular chain affect the crystallinity of the polymer as well as the size of the spherulites; the size of these spherulites is directly related to the strength and toughness of the polymer ； Modification works in the same way: controlling the polymer’s crystallinity and spherulite size to enhance toughness. Email: ellen1522@163.com.
Generally, the molecular weight is adjusted by regulating the methyl acetal, but the proportions of different grades of polyoxymethylene, pentaerythritol, trioxymethane, and formaldehyde vary