热处理对聚丙烯腈纳米纤维膜性能的影响

Influence of heat treatment on polyacrylonitrile nanofiber membrane property

为改善聚丙烯腈(PAN)纳米纤维膜力学性能和热稳定性,获得低成本耐高温的纤维过滤材料,对PAN纳米纤维膜在180℃、200℃、220℃、240℃温度下进行热处理,分析不同处理温度对其形态结构、透气性、热重性能和过滤性能的影响。结果表明:随着处理温度升高,PAN纳米纤维膜的颜色逐渐加深,纤维直径逐渐减小;热处理使PAN发生脱氢、氰基环化和热裂解等反应,导致纤维膜厚度和透气性降低,拒水性随着处理温度的升高不断增强;热处理使得PAN纳米纤维膜中形成了耐热性能优异的梯形分子结构,提升了纤维膜热稳定性;随着处理温度的升高,PAN纳米纤维膜的断裂强度呈现先增加后减小的趋势。综合热处理温度对纤维膜各性能的影响,热处理温度选择200℃为宜。此时,所获得的PAN-200纳米纤维膜过滤效率为93.46%,过滤阻力为75.1 Pa,质量损失率为5%时所对应的温度为310℃,相比未处理的PAN纳米纤维膜热分解温度升高,PAN-200纳米纤维膜的纵向和横向断裂强力分别达到17.16 MPa和10.82 MPa,机械性能较好。

In order to improve the mechanical property and thermal stability of polyacrylonitrile(PAN)nanofiber membrane,obtain low-cost high temperature resistant fiber filter material,PAN nanofiber membrane was treated at 180℃,200℃,220℃and 240℃.The effects of different treatment temperature on morphology structure,permeability,thermogravimetric performance and filtration performance were analyzed.The results showed that the color of PAN nanofiber membrane was deepened and the diameter of PAN nanofiber was decreased with the increase of treatment temperature.Heat treatment results in dehydrogenation,cyclization and thermal cracking of PAN,thickness and permeability of the membrane were decreased,water repellency of the membrane was increased with the increase of temperature.Heat treatment results in the formation of trapezoidal molecular structure with excellent heat resistance in PAN nanofiber membrane,which improved the thermal stability of the membrane.The breaking strength of PAN nanofiber membrane was increased first then decreased with the increase of treatment temperature.Considering the effect of heat treatment temperature on the property of fiber membrane,the heat treatment temperature of 200℃ was appropriate.The obtained PAN-200 nanofiber membrane filtration efficiency was 93.46%,filtration resistance was 75.1 Pa,and the corresponding temperature was 310℃ when the mass loss rate was 5%,which was higher than the thermal decomposition temperature of the untreated PAN nanofiber membrane.The longitudinal and transverse breaking strength of PAN-200 nanofiber membrane was 17.16 MPa and 10.82 MPa respectively,and the mechanical property was better.