预辐照接枝丙烯酸、苯乙烯磺酸钠对聚全氟乙丙烯膜性能的影响

采用常温下γ射线预辐照引发接枝的方法,在聚全氟乙丙烯(FEP)上接枝了丙烯酸(AA)和对苯乙烯磺酸钠(SSS),制备了一种含羧酸基团和磺酸基团的接枝膜.傅立叶变换红外光谱(FT-IR)分析证明了磺酸基团和羧酸基团的成功引入.采用XRD、TGA和接触角研究了接枝率对FEP膜的结晶度、热学特性及亲水性等性能的影响.结果表明,随着制备的FEP膜接枝率的增加,膜的结晶度、热稳定性和接触角逐渐减小;与此相反,FEP膜的亲水性能随接枝率的增加而增加.接枝膜湿敏性能测定结果表明,在相对湿度从5%RH变化到98%RH时,接枝膜电阻线性变化范围接近3个数量级,具有响应速度快(吸附<1min,解吸<2min),湿滞小(<3%RH)的特点,具有应用于电阻型湿度传感器的广阔前景.

EFFECTS OF PRE-IRRADIATION GRAFTING OF ACRYLIC ACID AND SODIUM STYRENE SULFONATE ON THE PROPERTIES OF FEP MEMBRANES

Acrylic acid(AA) and sodium styrene sulfonate(SSS) were grafted onto poly(tetrafluoroethylene-co-hexafluoropropylene)(FEP) membranes by pre-irradiation method,and a humidity sensing membrane with strong acid and weak acid groups was prepared.Grafting was carried out by using γ-ray from 60 Co at room temperature.Thermal and chemical properties of the grafting membranes were investigated.Infrared spectroscopy analysis of the grafting membrane confirmed the existence of sulfonate and carboxylic acid groups in the grafting membranes.The thermal behavior of grafting membranes was evaluated by TGA,and the results show that the higher the grafting yield is,the higher the char residue,which indicates that the branch chains including —SO_3Na and —COOH provide catalytic impetus to the charring.The degree of crystallinity of grafting membranes containing —SO_3Na and —COOH groups decreased with the increase of the grafting yield.The static contact angle with water of the grafting membrane decreases meanwhile the hydrophilicity of the grafting membrane increases with increasing the grafting yield.The electrical response properties of the grafting membrane to humidity was examined,too.The resistive of the grafting membrane changes linearly by 3 orders of magnitude over almost the whole humidity range(5%～98%RH).Furthermore,the grafting membrane exhibits a quick response(absorption:less than 1 min;desorption:less than 2 min) and small hysteresis(less than 3%RH).The FEP-AA-SSS membrane can be a promising approach to the development of new humidity sensitive materials with good sensing characteristics.