Study On The High Efficiency Thermo-stabilizer Of POM

The antioxidant and the formaldehyde absorbent are the two kinds of the most important thermo-stabilizer for polyoxymethylene(POM). At present, the phenolic antioxidant such as Irganox245 is commonly used as the main antioxidant of POM in industry, however, there also exist some problems with high dosage and high cost for this kind of antioxidant. In this thesis, two kinds of high efficiency antioxidant F1 and F2 of POM were probed out in order to further improve the thermal stabilization and reduce the production cost of POM. On the other hand, in order to solve the problems that the low-molecule weight formaldehyde-absorbent such as melamine (MA) is easy to volatilize during high-temperature melting process resulting in the loss of the compound, reduction of the thermo-stabilizing efficiency and formation of the mould deposit, in this paper, MA was polymeric modified by condensation reacting with proper reacting molar ratio of formaldehyde (FA) through ultrasonic irradiation to obtain the ultra-fine, cross-linked, and the thermo-stable melamine-formaldehyde (MF) polycondensate, which can be used to replace MA as the formaldehyde absorbent and the nucleation agent of POM in the meantime.The thermal stabilization effect of antioxidant F1 on POM was studied by the measurements of isothermal weight loss analysis at 220 ℃, isothermal weight loss rate analysis at 222 ℃, balance torque analysis, formaldehyde emission amount analysis, multiple processing and long-term aging analysis in comparison with the commonly used antioxidant Irganox245 for POM. By using antioxidant F1 instead of Irganox245 can make the thermal weight loss, thermal weight loss rate and formaldehyde emission amount of POM decrease, and improve the balance torque and the melt viscositry of POM. After five times of extrusion, the yellow index (YI)...