共查询到17条相似文献,搜索用时 78 毫秒
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采用磷酸在超声下对聚对苯二甲酰对苯二胺(PPTA)纤维进行表面改性,并根据试验条件进行了正交试验设计。对处理后的样品进行了扫描电镜、接触角、单丝断裂强度测试。结果表明该方法能够在对纤维本身力学性能无明显损伤的情况下,有效地改善其表面润湿性。另外还对试验结果进行了统计分析,对最佳试验条件的选择进行了初探,并讨论了各个因素对试验结果影响的显著性大小。 相似文献
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高分子量PPTA树脂在浓硫酸中的热稳定性与温度、溶液浓度以及溶解时的搅拌速度有关。随着温度升高,其热稳定性降低;当溶液浓度低于16%(W/W)时,浓度越低其热稳定性越差,当溶液浓度达到16%以上时,浓度对其热稳定性没有明显的影响;溶解时搅拌速度增大,其热稳定性变差;不同分子量的PPTA树脂在硫酸中的热稳定性基本相同。 相似文献
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聚对苯二甲酰对苯二胺(PPTA)与导电性聚苯胺(PAn)共混,得到一种既有PPTA的液晶性,又有PAn导电性的全新材料。PPTA和PAn以不同质量比共溶于浓硫酸后,可制成线材及薄膜,在1mol/1HCl水溶液中成型及拉伸。实验结果表明:PPTA的液晶性随PAn加入量的增加稍有减弱;线状PPTA/PAn的抗张强度随PAn混入量的增加而增大(从41.20N/mm~2增至44.80N/mm~2);断裂伸长与PAn混入量的多少无关(仍保持在4%),PPTA/PAn复合物的电导率随PAn含量的增加而升高,当PPTA:PAn=2:1(质量比)时,其电导率为2.3×10~(-1)S/cm,较纯PAn(3-5S/cm)小一个数量级,复合物的衍射图在2θ=22.7°及25°处有两个峰,分别与纯PPTA及统PAn的峰的位置相同,因此说明二者是以分子复合形式存在。SEM图表明复合物线材表面呈取向排列,且PPTA与PAn混合均匀。 相似文献
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聚对苯二甲酰对苯二胺的合成方法 总被引:1,自引:0,他引:1
分别介绍了聚对苯二甲酰对苯二胺的应用及界面缩聚法、酯交换法、气相聚合法、低温溶液缩聚法、直接缩聚法等几种合成方法的优缺点,分析了国内外聚对苯二甲酰对苯二胺的发展趋势。 相似文献
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主要研究了聚对苯二甲酰对苯二胺聚合体酸洗工艺,包括酸洗浓度、温度及时间等,通过对比实验获得最佳酸洗条件。结果表明,在当稀硝酸浓度为0.03%、洗涤温度为25℃和洗涤时间为20 min时,可以使聚对苯二甲酰对苯二胺聚合体灰分质量分数降至5×10-5以下,比纯水洗涤效果好很多。 相似文献
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The high-temperature crystallization of poly(p-phenylene terephthalamide) (PPTA) from dilute organic solutions was achieved through the introduction of a non-solvent, or precipitating agent, at the desired crystallization temperature. The morphology and crystal structure were examined for crystals produced from PPTA polymer with two different molecular weights (Mw = 46000 and 3430 g mol−1), using transmission electron microscopy. For the high-molecular-weight polymer, ribbon-like crystals were produced, while the low-molecular-weight polymer yielded small needles or platelets. In both cases, electron diffraction showed that the Northolt allomorph was obtained. For the high-molecular-weight polymer, the molecular axes were parallel to the ribbon axes in a chain-extended type structure. A hypothesis for the orientation of the low-molecular-weight PPTA in the small platelets, is also given. 相似文献
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Thermal decomposition of a series of 1 : 1 mixtures of typical polymer waste materials [polyethylene (PE), poly(propylene) (PP), polystyrene (PS), polyacrylonitrile (PAN), polyisoprene, poly(methyl methacrylate) (PMMA), polyamide‐6 (PA‐6), polyamide‐12 (PA‐12), polyamide‐6,6 (PA‐6,6), and poly(1,4‐phenylene terephthalamide) (Kevlar)] with poly(vinyl chloride) (PVC) was examined using thermal analysis and analytical pyrolysis techniques. It was found that the presence of polyamides and PAN promotes the dehydrochlorination of PVC, but PVC has no effect on the main decomposition temperature of polyamides. The hydrogen chloride evolution from PVC is not altered when other vinyl polymers or polyolefins are present. The thermal degradation of PAN is retarded significantly, whereas that of the other vinyl polymers is shifted to a slightly higher temperature in the presence of PVC. Among the pyrolysis products of PAN‐PVC mixture methyl chloride was found in comparable amount to the other gaseous products at 500°C pyrolysis temperature. 相似文献
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用热分析法研究了阻燃剂聚丙烯酸五溴苄基酯在空气和氮气气氛中的热分解动力学。该阻燃剂在空气气氛中为两步分解,在氮气气氛中为一步分解,利用Friedman法求出聚丙烯五溴苄基酯的第一步分解反应的活化能变化趋势,同时利用Satava-Sestak法研究了其热分解机理。结果表明,在0.10至0.90的转化率范围内,聚丙烯酸五溴苄基酯在空气气氛下的活化能为167.35kJ/mol,在氮气气氛下的活化能为171.94kJ/mol,热分解机理均为Avrami-Erofeev方程,随机成核和随后生长,反应级数分别为n=23和n=12。动力学方程分别为G(a)=[-ln(1-a)]23和G(a)=[-ln(1-a)]12。 相似文献