Study On Improving Crystallization Property Of Polyoxymethylene

POM is a kind of molecular chain,it is an engineering plastic with neat structure,no side chain and high crystallinity.It has excellent comprehensive properties and many applications.But the polyformaldehyde and its products have lower notch impact strength,poor toughness and easy cracking of parts,and it can not meet the needs of the application of certain field,while the domestic polyformaldehyde is particularly prominent in this regard,in the current fierce market competition,in order to keep their living space,they need to improve the crystallization of polyformaldehyde to enhance product performance.In this paper,the imported and domestic polyformaldehyde crystallization properties were studied by polarizing microscope and DSC.Comparing the imported and domestic polyformaldehyde,we have found that for the imported polyformaldehyde,the number of crystalline nucleation and the crystallization temperature was higher,the crystallization speed was faster and the spherulite size was smaller than that of domestic polyformaldehyde.It is found that the difference of the crystalline properties leads to the difference of mechanical properties between the notch and the impact strength by testing the mechanical properties.The paper studies the effect of 3 organic nucleating agents(A,B and C)on crystallization behavior of polyoxymethylene.The results showed that nucleating agent C could increase the nucleation amount of polyoxymethylene,increase the crystallization temperature,accelerate the speed,decrease the spherulite size and improve the mechanical properties.The nucleating agent A and B can improve the crystallization of polyoxymethylene,but the effect is not as good as that of C,and nucleating agent A and B will lead to yellowing of polyoxymethylene.By the simulation of nucleating agent for industrial application,we can verifiy the applicability of nucleating agent C,the results showed that the nucleating agent C improved the crystallization of polyoxymethylene M90 and M270 significantly,and the mechanical properties were also improved,which had no effect on the thermal stability of polyoxymethylene.It was verified that the nucleating agent C was completely suitable for improving the crystallization properties of polyoxymethylene products.In the range of 0.5%,with the increase of nucleating agent content,the improvement effect of crystallization is better.