高亲水性聚四氟乙烯微粉的制备及其性能研究

Preparation of High Hydrophilic PTFE Powder and Its Dispersion Stability

通过预辐射接枝方法在聚四氟乙烯(PTFE)微粉上成功接枝丙烯酸(AAc)和2-丙烯酰胺-2-甲基丙磺酸(AMPS),制备了高亲水性的PTFE微粉.采用红外光谱(FTIR)、X射线光电子能谱(XPS)和接触角(CA)测试表征了改性PTFE微粉的化学结构和亲水性变化;采用扫描电子显微镜(SEM)观察改性PTFE微粉表面形貌;采用电泳法测试了改性PTFE微粉的zeta电位;通过热重分析(TGA)测试了辐射接枝对PTFE微粉热稳定性的影响.结果表明,改性PTFE微粉亲水性和分散稳定性随着接枝率的增加而增强;在单体浓度为20%,AAc与AMPS之比为2且反应温度为70℃时接枝率达到26.6%,此时改性样品PTFE-g-P(AAc-co-AMPS)在水溶液中的分散稳定性效果较好,并能够长期稳定存在.水接触角由改性前的148.8°下降到改性后的30.2°,对应的zeta电位从-4.3 m V降为-83.4 m V.

Acrylic acid （AAc） and 2-acrylamide-2-methylpropanesulfonic acid （AMPS） were successfully grafted on polyterafluoroethylene （PTFE） powder by the fact that T-ray radiation induced graft coploymerization for preparation of high hydrophilic PTFE powder. The chemical structure and hydrophilicity of the grafted PTFE powder were characterized by Fourier transform infrared spectrometer （FTIR）, X-ray photoelectron spectroscopy （XPS） and contact angle （CA）test. The surface morphology of the grafted PTFE powder was observed through scanning electron microscope （SEM）. The electric potential of the grafted PTFE powder dispersion was determined by zeta potential test. The thermal stability of the grafted PTFE powder was analyzed by thermogravimetric analysis （TGA）. It was found that the hydrophilicity and dispersion stability of modified PTFE powder was significantly improved with increasing grafting yield of AAc and AMPS. The PTFE powder with a grafting yield of 26.6% can be stably dispersed in water for a long period ,which was prepared in the solution with the monomer concerntration of 20% and the AAc/AMPS ratio of 2 at 70℃. Water contact angle of the PTFE powder decreased from 148.8° before grafting to 30.2° after grafting. Simultaneously,the corresponding zeta potential of PTFE dispersion decreased from - 4.3 mV to - 83.4 mV.