Study On The Properties Polyoxymethylene/high Desity Polyethylene/ Compatibilizer Blends

The study on the modification of polyoxymethylene (POM) is always focused on the academia and industrial field. In this paper, the POM has been modified and compatibilized by adding high-density polyethylene (HDPE) and compatibilizer.This paper summarized the research progress on the blending and compatibility of the POM. The appropriate amount of HDPE modifier and POM were studied in the twin-screw extrudsion melt blending, and the effects of HDPE and the compatibilizer on the mechanical properties, tribological properties, compatibility and crystallization of POM blends were mainly discussed. The mechanical properties of the POM/HDPE/compatibilizer blends were investigated by tensile and impact tests. The tribological properties of POM were studied with friction coefficient, wear volume and the worn surface. Meanwhile, the crystallization was analyzed by the differential scanning calorimeter (DSC) measurement.The results showed that an appropriate amount of HDPE improved the friction and wear properties of POM. In the course of friction and wear, the debris produced by HDPE prevents the steel counterpart from POM surface, thus reduces the frictional heat and decreases the temperature of the worn surface effectively, as a result the friction and wear properties were improved. The wear loss of the POM/HDPE blends decreased when adding the different compatibilizers, The friction coefficient of the blends reduced when using the ethylene acrylic acid (EAA) and the EAA/acrylic copolymer (ACR) as the compatibilizer. But when the compatibilizer were the ACR and ethylene cinyl acetate (EVA), the friction coefficient increased. Therefore, the compatibilizer to some extent improved the friction and wear properties of the POM/HDPE blends. The friction and wear properties of the blends reach the best value (friction coefficient: 0.082, wear loss: 14.5 mg) with the POM/HDPE/EAA ratio of 90/10/2.The POM/HDPE blends was an incompatible system, the compatibility between the two phases was very poor. The shape of HDPE particles was irregular in the POM/HDPE blends, and their sizes were not the same and the distribution of particles were asymmetric, and the peeling phenomenon were very evidence between the particles and matrix. When EAA compatibilizer was added in POM/HDPE blends, HDPE particles dispersed into more uniform small and spherical particles, they increased the contact area between the matrix and dispersed phase, and reduced space between particles, which indicated to improve compatibility between POM and HDPE with adding EAA.The addition of HDPE has a great influence on tensile strength and notched impact strength of POM, and the mechanical properties decreased rapidly when the added amount of HDPE increased. In the context of this study, when the different types of compatibilizer were added to a certain quality of POM/HDPE blends, the results showed that the compatibilizer EAA could improve the mechanical properties, the mechanical properties of blends reached the best value with the POM/HDPE/EAA ratio of 90/10/2.The DSC cooling curves measurement suggests that the crystallization of POM was improved by adding HDPE and compatibilizer, whereas being little effect on the crystallization temperature. The thermal stability tests showed that the additions of HDPE and EAA can improve the thermal stability of POM.