芳纶纤维增强PE-RT管耐高温性能的试验研究

Experimental study on the thermostable property of aramid fiber reinforced PE-RT pipes

柔性复合管具有超高强度、高模量、耐酸碱腐蚀、重量轻等优良性能,但其耐高温性能却较差,存在一定的安全隐患。为此,以内衬层为高温聚乙烯(PE-RT)、增强层为芳纶纤维的柔性复合管为试验样品,利用高温高压釜、差热扫描仪等设备开展了不同工况、不同温度条件下的试验研究,以及整管承压能力和1 000 h存活试验。结果表明:①在环境相容性试验中,高温对柔性复合管内衬层PE-RT的重量、维卡软化温度、力学性能及结构组成影响不大,但是对增强层芳纶纤维的拉伸性能、整管水压爆破影响较明显;②导致整管承压能力下降的原因是增强层在受内压的过程中,芳纶纤维发生形变和断裂;③随着温度上升,会导致分子热运动的解取向和结晶,非晶取向降低,结晶度、晶区取向因子逐渐升高,大分子链的解取向增加,拉伸强度下降。结论认为,该类型柔性复合管能顺利通过1 000 h存活试验,推荐在工况介质温度不大于95℃、内压不大于4 MPa下使用。

Flexible composite pipes are advantageous in ultra high strength, high modulus, pH and corrosion resistance and light weight, but there are still some hidden safety troubles because they are poorer in thermostable capacity. Therefore, test samples of flexible composite pipes were prepared with high-temperature polythene （PE-RT） as the neck bush and aramid fiber as the reinforce- ment layer. Experimental study was conducted by using HPHT vessel and differential thermal scanner for different working condi- tions, different temperatures, whole-pipe pressure-bearing capacity and 1000 h viability. It is shown by the environmental compati- bility test that high temperature has little effect on the weight, Vicar softening temperature, mechanical properties and structures of neck bush PE-RT, but exerts an obvious effect on the tensility and whole-pipe water pressure blasting of the reinforcement aramid fi- ber. Besides, the drop of whole-pipe pressure-bearing capacity is caused by deformation and breaking of aramid fibers when the rein- forcement layer is under the force of internal pressure. Finally, disorientation and crystallization of molecular thermal motion occur with the rise of temperature, so amorphous orientation reduces, crystallinity factor and crystalline orientation factor increase gradu- ally, thus, disorientation of macromolecular chains increases and tensile strength decreases. It is concluded that this type of flexible composite pipe can smoothly pass 1000 h viability test. And it is recommended that it be used in the situations with temperature not higher than 95 ℃ and internal pressure not higher than 4 MPa.