Preparation of High Strength and Toughness Aramid Fiber by Introducing Flexible Asymmetric Monomer to Construct Misplaced-Nunchaku Structure

High performance fibers with high strength and toughness have great potential in composites, but contradiction between tensile strength and elongation at break makes the preparation to become a current challenge. Herein, an asymmetric structure of more flexible diamine, 3,4′-diaminodiphenyl ether (3,4′-ODA), is introduced into heterocyclic aramid (PBIA) fibers to replace rigid symmetric p-phenylenediamine (PDA). By studying the properties of copolymer (mPEBA) fibers with different ratios of diamine, it is found that the mPEBA fiber reached the optimal mechanical properties with the 30% content of 3,4′-ODA. Compared with homopolymerized heterocyclic aramid fibers, the tensile strength and elongation at break of mPEBA fiber are improved by 26.2% and 38.7%, respectively. Results of X-ray diffraction show that the introduction of 3,4′-ODA structure can increase stretchability of mPEBA fibers, improving the orientation degree during hot-drawing. Molecular dynamics simulations confirm that 3,4′-ODA structure undergoes a conformation transformation to form a straightened chain during hot-drawing, while symmetrical 4,4′-diaminodiphenyl ether (4,4′-ODA) cannot form the same conformation. The misplaced-nunchaku structure is formed based on the special meta-para position of 3,4′-ODA, achieving the synergy of high strength and high toughness.     

用直接纺丝法制芳纶短纤维

研究了直接纺丝制取芳纶短纤维的新方法。讨论了纤维长度、直径及力学性能与纺丝条件的关系。发现影响纤维长度的主要因素是空气层高度和喷丝速度,影响纤维直径的主要因素为喷口直径及喷丝速度。此外,还用PPTA短纤维制成了均匀的PPTA"浆粕"纤维。     

芳纶及其功能织物的研究动态

芳纶是一种耐高温的高强高模特种纤维。介绍了间位芳纶和对位芳纶的结构和性能,以及当前利用其性能制得的各种功能芳纶织物。指出芳纶今后的研究方向:更高的力学性能,130～170GPa的弹性模量,60～90GPa的抗拉强度;更多的功能特性,尤其是耐500～600℃高温的特性。以期芳纶功能织物特性大幅度提高,应用更广泛。     

UV photo‐stabilization of tetrabutyl titanate for aramid fibers via sol–gel surface modification

Tetrabutyl titanate was used as sol–gel precursor of a nanosized TiO₂ coating to improve the photo‐stability of aramid fibers. The nanosized TiO₂ coating was characterized by XRD and XPS. The influence of the TiO₂ coating on photo‐stability of aramid fibers was investigated by an accelerated photo‐ageing method. The photo‐stability of aramid fiber showed obvious improvement after coating. After 156 h of UV exposure, the coated fibers showed less deterioration in mechanical properties with the retained tensile strength and elongation at break greater than 36 and 50% of the original values, respectively, whereas the uncoated fibers degraded completely and became powdery. SEM analysis showed no significant surface morphological change on the coated fiber after the exposure, while some latitudinal crack fractures appeared on the uncoated aramid fiber. The effect of the nanosized TiO₂ coating was also well demonstrated by examining the difference of distributions of C1s in XPS deconvolution analysis on the surface of uncoated/coated fibers with increasing UV exposure time. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3113–3119, 2007     

酸性KMnO_4条件下芳纶纤维的表面改性研究

利用KMnO4在酸性的环境中具有氧化性的特性对芳纶纤维进行表面改性研究,分析其表面形貌、强力以及拉伸性能的变化;采用扫描电子显微镜观察处理前后芳纶纤维的表面形态特征;以夹角余弦幅度法确定权重;利用模糊正交法的理论与方法处理试验数据,得出模糊综合评价值.从而得出最佳实验指标为:硫酸质量分数10%,KMnO4质量浓度5 g/L,处理温度为30℃,处理时间35 min.     

芳纶帘线——轻型载重子午线轮胎理想的胎体骨架材料

采用芳纶帘线替代普通聚酯帘线进行轻型载重子午线轮胎的生产，并将两种化胎性能进行了对比。结果表明，采用芳纶帘线生产的轮胎静负荷性能、耐外性能、强度性能及高速性能等均可达到普通聚酯帘线轮胎的水,轮胎的刚性、转向能动性和驾驶性能提高，而且还可提高生产效率，同时减小了轮胎质量，节约了成本。     

高性能纤维的性能及应用

高性能纤维是具有特殊的物理化学结构、性能和用途,或具有特殊功能的化学纤维。简述了高性能纤维的基本分类,并介绍了芳纶纤维、PBO纤维、碳纤维、玻璃纤维四种高性能纤维的性能及应用,并分析了高性能纤维今后的发展趋势。     

芳纶纤维表面改性及其对芳纶纸力学性能的影响

利用氯磺酸、醋酸酐对芳纶短切纤维进行了改性处理,再用处理后的纤维配抄芳纶纸,探讨了处理工艺对芳纶纸力学性能的影响.结果表明,当氯磺酸浓度为2%,处理时间为10min,处理温度为50℃时,芳纶纸的力学性能较好.用100%的醋酸酐对芳纶纤维进行处理然后配抄成纸,所得纸张的抗张指数和撕裂指数分别提高了63.8%和21.4%.另外,芳纶纤维经过醋酸酐浸泡1min后再用甲醇处理3min,芳纶纸的抗张指数和撕裂指数分别提高了84.7%和38.4%.     

聚碳酸酯基聚氨酯/芳纶纤维复合材料的制备与性能

以聚碳酸酯二元醇为软段,利用预聚体法制备了系列聚碳酸酯基聚氨酯/芳纶浆粕纤维(Aramid pulp)复合材料,研究了芳纶浆粕纤维对聚碳酸酯基聚氨酯弹性体(PUE)力学性能的影响。采用扫描电镜、X射线衍射、差示扫描量热分析、热重分析、红外光谱及电子拉伸机等测试仪器对聚氨酯复合材料的结构与性能进行了表征和分析。结果表明,芳纶浆粕纤维能有效实现对聚氨酯弹性体的增强作用,其中对撕裂强度的增强尤为突出。当芳纶浆粕纤维用量为0.5%时,复合材料的撕裂强度由106 k N/m提高到120 k N/m,表现出最好的力学性能;芳纶浆粕纤维在聚氨酯中分散均匀,提高了复合材料的热稳定性。     

芳纶纤维布粘贴加固桥梁下部施工方法的探索

介绍了芳纶纤维布粘贴加固旧桥施工的工艺原理,对其施工工艺流程作了简要论述,并对施工准备、混凝土表面清理、涂刷底胶、粘贴、加固等工序的操作要点进行了详细阐述,给出了施工质量控制措施,指出该工法具有良好的社会效益和经济效益。