高温对几种有机高性能纤维力学性能及结构的影响

The effect of high temperature on the tensile properties and structure of several organic high-performance fibers

轻质高强、温度适应范围广的有机高性能纤维常应用于高温过滤、国防军事、特殊防护、航空航天等领域。为探究几种有机高性能纤维的耐热性能及结构变化,采用扫描电子显微镜、热重分析仪、傅里叶红外光谱仪研究了聚酰亚胺纤维(PI)、聚芳酯纤维(PAR)Vectran■、聚芳酯纤维(PAR)Yokolar■和芳纶Ⅲ纤维在200℃~350℃高温下处理一定时间后的表面形貌、拉伸性能、化学结构变化。结果表明:PI、Vectran?、Yokolar■和芳纶Ⅲ单纤维拉伸断裂应力分别为3.3 GPa、4.0 GPa、3.9 GPa和5.0 GPa,经过200℃~350℃高温条件长时间处理后,PI纤维表面无明显缺陷,其余三种纤维沟槽、颗粒等缺陷结构增多;PI纤维的红外光谱图特征峰没有特别明显的变化,相应官能团未被高温完全破坏,其他三种纤维红外光谱图中特征峰强度有不同程度减弱或消失,有化学键发生断裂;耐热性能PI>芳纶Ⅲ>Vectran■>Yokolar■,质量损失5%时对应的温度分别为529℃、506℃、472℃和445℃;分子链的断裂和表面缺陷增多是纤维力学性能下降的关键影响因素。

Lightweight,high-strength,organic high-performance fibers with a wide temperature range are often used in high-temperature filtration,national defense,military,special protection,aerospace and other fields.In order to explore the heat resistance and structural changes of several organic high-performance fibers,i.e.,the polyimide fiber(PI)and polyarylate fiber(PAR)■,polyarylate fiber(PAR)Yokolar■ and aramidⅢfiber,Vectran scanning electron microscope,thermogravimetric analyzer,and Fourier infrared spectrometer were used to study.The surface morphology,tensile properties,and chemical structure changes of four organic high-performance fibers after being treated at a high temperature of 200℃to 350℃for a certain period of time.The results show that:PI,Vectran■ ,Yokolar■ and AramidⅢfiber have a breaking stress of 3.3 GPa,4.0 GPa,3.9 GPa and 5.0 GPa.After a long time treatment at 200℃~350℃,the PI fiber surface has no obvious defects,the other three types of fiber grooves,particles and other defect structures have increased.The characteristic peaks of the infrared spectrum of PI fiber have not changed significantly,and the corresponding functional groups have not been completely destroyed by high temperature.The other three kinds of fibers′infrared spectra characteristic peaks have different degrees of weakening or disappearance,some chemical bonds are broken;heat resistance PI>AramidⅢ>Vectran■>Yokolar■ ,the temperature corresponding to 5%mass loss is 529℃,506℃,472℃and 445℃.Molecular chain breakage and the increase of fracture and surface defects are the key influencing factors for the decline of fiber mechanical properties.