Preparation Of The Acrylate Polymers Used For Modification Of POM And The Ageing-resistance Of The Modified POM

Polyoxymethylene is a kind of universal engineering plastics which has broad foreground of application with excellent mechanical properties, electrical properties , wear resistance, chemical-resistant properties and good lubrication by oneself. However, the application is limited for the reason of poor ageing-resistance of POM caused by it's molecular structure. An important task is to improve its ageing-resistance.At first, acrylate polymers used for modifying POM was prepared via emulsion polymerization in this paper. Stirring speed, reaction temperature and reaction time of polymerization were designed for the uses of reaction and engineering. The effects of polymer synthesized by different monomer and quantity on the POM were researched , and the recipe was designed . The structure of the obtained polymers were characterized and researched by means of GPC and TEM etc. The results show that the polymerization can be carried out when the rotation speed is 390rpm , the temperature is about 75-90℃, the reaction time is 120min . The Mw of acrylate polymers is about 2.57e5g/mol . Diameter analysis indicates that the dimension of polymer particles is between one hundred and hundreds of nanometer , the shape of particles is inerratic .Secondly, the obtained polymers were used to modify POM . The compatibility between polymer and POM was observed by SEM. The effects of polymers on POMwere researched by measuring tensile strength, impact strength and color aberration of modified and unmodified POM after UV ageing, thermal ageing and hot water ageing. The SEM micrographs show that acrylate polymers can be compatible with POM well. The mechanical properties tests indicate that the modified POM has good properties. The retention rate of tensile strength, impact strength and elongation at break are 99.5%, 56.1%, 100% after UV ageing 1000 hours, 105.0% , 92.8%, 100.0% after thermal ageing for 1000 hours at 120℃, 103.6%, 82.5%, 101.8% after hot water ageing for 1000 hours at 90℃. The mechanical properties, are improved largely. The color aberration of POM after UV ageing , thermal ageing and hot water ageing for 1000 hours are 5.9, 6.land 4.8, smaller than 34.5, 7.6 and 20.2, which are the value of unmodified POM .At last, the system was scaled up to 1000 t/a and the samples were aged by accelerating ageing test. The results show that the POM can be produced well and a good ageing-resistance can be realized . The tensile strength , impact strength and elongation at break are 55.3MPa, 6.25kJ/m2 and 74.0% , respectively, and the retention rate are 101.5%, 78.1%, 65.0%, respectively.