可熔融加工PTFE对FEP在干/湿环境中摩擦磨损性能的影响

为建立含氟聚合物的使用性能与干湿工作环境的关系,采用热压成型的方式制备聚四氟乙烯(PTFE)试样,并通过挤出注塑成型方法制得可熔融加工PTFE(M-PTFE)/聚全氟乙丙烯(FEP)共混物.研究PTFE和FEP的相关性能,特别是M-PTFE/FEP共混物的力学性能以及在干、湿状态下的摩擦磨损性能.结果表明:在研究的配比范围内,共混材料的拉伸强度随着M-PTFE含量的增加而增大.干摩擦条件下,M-PTFE的质量分数≤20%时,增加MPTFE含量可降低试样的摩擦系数与体积磨损率,但M-PTFE的质量分数达到30%时两个参数均会增大.湿摩擦条件下,试样的摩擦系数和体积磨损率与M-PTFE的添加量之间无规律性,但都低于干摩擦条件的值.对磨面形貌的SEM照片分析表明:在干摩擦条件下,增加M-PTFE添加量会促进转移膜的形成和完善,但湿摩擦会抑制转移膜的形成.

可熔性聚全氟乙丙烯色母粒的研制

通过TG、DSC、高精度测色仪及SEM测试分析,确定了FEP色母粒中载体树脂、颜料和分散助剂的成分及三者的配比,FEP色母粒的加工设备和工艺条件,并将色母粒法与直接着色法进行了对比.实验结果为：FEP色母粒中,载体树脂为熔体指数在4.5～8.5g/10min的FEP粉料,颜料为可耐380℃以上高温的无机颜料,分散助剂为分散剂D（Tm=204℃,Td=427℃）;为满足FEP着色成品介电性能要求,颜料含量不可过高,且分散要好,进而确定了颜料与分散剂D的最佳添加量;双螺杆挤出机加工FEP色母粒较单螺杆挤出机的剪切及塑化更充分,利于颜料进一步分散.实验表明：颜料在FEP着色成品中分散效果,色母粒法远优于直接着色法.

Influence of pH to Increase Grafting Degree into Fluoropolymers

Poly(ethylene-alt-tetra-fluoroethylene (ETFE) and poly(tetrafluoroethylene-cohexafluoropropylene) (FEP) were pre-irradiated under air using a Co60 gamma source to graft styrene at low pH. Grafting copolymers were tuned by study of different parameters (monomer, reaction time, temperature, and pH with addition of sulfuric acid (H2SO4)). The maximum degree of grafting was 80% and 40% for ETFE and FEP respectively at dose 2 kGy. Influence of low pH in grafting degree by adding sulfuric acid was studied. Grafting degree was examined by infrared (FTIR-ATR), differential scanning calorimetry (DSC) and swelling behavior analysis after sulfonation process.