Development And Research Of Polyoxymethylene Composites On Reinforcement, Toughening And Wear-Resistance Modification

Polyoxymethylene (POM) is a kind of thermoplastic engineering plastics that has good mechanical properties, self lubrication performance and excellent wear resistance, in addition, POM is easy to process and thus POM is widely used in machinery industry, automotive, electronic appliances and other fields.With the rapid development of the national economy, it put forward higher requirements for performance of POM.It is necessary to modify POM by means of enhancement, filling and toughening in order to meet the higher requirements conditions and applicate in more areas by practical and engineered POM. This paper mainly includes two parts.The first part is about the study on enhancement modification of POM.In this paper, waste carbon fiber (RCF), glass fiber (GF) and basalt fiber (BF) were used to reinforce POM. Because RCF surface contains a lot of impurities while the nitric acid and silane coupling agent KH570was used to clean and activate RCF surface. The mechanical test indicated that the incorporation of fiber enhanced the mechanical peoperties of POM, wherein RCF reinforced best. The micro morphology of impact fracture analysis showed that the fiber and resin bonded well.The crystallization behavior and thermal properties of POM/RCF composites was researched.The DSC was employed to investigate the crystallization behaviors of POM copmosites.The non-isothermal and isothermal crystallization studies showed that RCF acted as crystal nucleus,which raised crystallization rate,improve the degree of crystalline and reduced the activation energy of the crystallization process.The thermal properties of POM/RCF were studied by DMA and TGA.In addition,by adjusting the screw speed of the twin-screw extruder,the optimal processing conditions for composites mechanics performance was determined.The second part is about the study on wear-resistance and toughening modification of POM.Polytetrafluoroethylene (PTFE) fiber and basalt fiber POM were employed to modify the wear-resistance and toughening on POM. The friction measurement indicated that PTFE fiber can effectively reduce the coefficient of friction and slightly decrease the wear loss of POM.Blending with PTFE fiber and BF, the coefficient of friction and wear loss were both reduced and the mechanical properties of POM composites was improved.The DSC non-isothermal crystallization tests showed that PTFE fiber had no effect on POM, while BF improved the crystallization temperature of POM.