辐射交联对磺化聚酰亚胺作为燃料电池用质子交换膜性能的影响

Effects of Irradiation Crosslinking on Properties of Sulfonated Polyimide Membranes

为了提高磺化聚酰亚胺膜的综合性能,特别是水解稳定性,文中以60Co为辐射源,对磺化聚酰亚胺进行γ射线辐射。辐射后,膜的相对分子质量通过凝胶渗透色谱进行测试,测试结果显示,辐射后膜的数均分子量和重均分子量都有明显提高。膜的分子结构由核磁和红外光谱测试确定,结果表明辐射和未辐射膜的核磁谱图和红外光谱谱图基本不变。对辐照不同时间交联膜的含水量、尺寸稳定性、质子传导率、膜稳定性和力学性能进行了测试,结果显示,24 h辐射处理能提高膜的综合性能,特别是水解稳定性得到了显著提高,膜在100℃去离子水中可以稳定存在960 h,是未交联膜的5.6倍。辐射对质子交换膜的氧化稳定性和力学性能都有提高,甲醇渗透率有所减小。辐射24 h的磺化聚酰亚胺膜仍保持了较高的质子传导率,在80℃去离子水中膜的导电率仍可高达到0.145 S/cm。实验表明适度辐射交联是提高磺化聚酰亚胺膜综合性能的一种有效方法。

In order to improve the comprehensive performance of sulfonated polyimide membranes,especially the hydrolysis stability,irradiation induced crosslinking was used to modify sulfonated polyimide membranes by 60Co as radiation source.The effects of radiation on the properties of sulfonated polyimide membranes were evaluated by studying the membrane parameters including the water uptake,dimensional change,proton conductivity,membrane stability,mechanical properties and methanol permeability.Compared with the corresponding uncross-linked sulfonated polyimide,the radiation crosslinking sulfonated polyimide membranes display the excellent water stability,oxidative stability and dimensional stability.The experimental results show the 24 h radiation treatment endows the sulfonated polyimide membranes with the optimum performance,remarkably improves the membrane stability.The membrane can endure for 960 h in 100℃deionized water,which is 5.6 times higher than non-crosslinked membrane.In addition,the oxidative stability and mechanical properties of membranes are also improved,the methanol diffusion is inhibited.The radiation 24 h sulfonated polyimide membrane still keeps a high proton conductivity,which shows a similar proton conductivity to Nafion 117,the conductivity of the membrane can achieve 0.145 S/cm in deionized water at 80℃.These results display that the moderation irradiation crosslinking is an effective method for improving the integrated performance of SPI membranes.