Preparation Of Thermostabilization And High Tenacity Polyoxymethylene Composites And Study On Structure And Properties

Polyoxymethylene(POM) is the widely used engineering plastics with excellent physical and chemical properties, mechanical properties and tribological properties. However, POM is easy to product formaldehyde at high temperature, and in hot condition with oxygen, formalaehyde would oxidize to formic acid, which lead to zippered depolymerization. POM is very extremely sensitive for ultraviolet light; in addition, POM shows notch sensitive with low impact strength, and flexibility is also poor, all of which limit the areas of the application of POM.Stabilizer copolyamide(COPA) and antioxygen 1010 were used to improve the thermostabilization and ultraviolet(UV) aging properties of POM. High performance thermoplastic polyester elastomers(TPEE) and polyether polyurethane elastomer(TPU) were used to modify the toughness of POM. The results were as follows:1. The effect of COPA and antioxygen 1010 on the thermostabilization and UV aging preperties was investigated, through comparing the crystallizability, thermal gravimetry (TG), mechanical property, melting index(MI) and rheological properties of POM before and after UV aging. It showed that COPA and antioxygen could decrease the spherulite size and enhance the crystallinity of POM, acting as nucleation effect on POM; which could improve the thermostability, and reduce losses of mechanical properties after UV aging. When the mixture ratio of POM/COPA/antioxgen 1010 was 100/0.5/0.5, the stability was best.2. The study on the effect of elastomers'(TPEE, TPU) content, mixture style on the spherulite size, micromorphological structure(SEM), mechanical property, thermostabilization and rheological property of POM. The results showed that notch impact strength increased by 60% than pure POM, when the content of TPU is 20%; when the content of TPEE is 20%, the notch impact strength increased by 120%; when the mixture ratio of POM/TPEE/TPU is 70/5/25, the notch impact strength of POM enhanced 24.4KJ/m2 from 9KJ/m2, increased by 1.7 times.3. The results indicated that the toughening effect of TPEE was better than TPU and TPEE/TPU mixture. Therefore, the thermostabilization and complex viscosity of POM improved.