低温溶液缩聚法直接制备PPTA浆粕基本规律的研究

对聚对苯二甲酰对苯二胺浆粕在N-甲基吡咯烷酮-氯化钙溶剂体系中低温溶液缩聚反应及熟化成纤过程的基本规律进行了研究，通过优化聚合工艺条件得到相对分子质量较高的PPTA浆粕，为采用双螺杆挤出机作为主反应器低温溶液缩聚法直接制备PPTA浆粕奠定基础。     

剪切速率对直接法制备芳纶浆粕缩聚反应影响的研究

研究了剪切速率对低温溶液直接缩聚法制备聚对苯二甲酰对苯二胺浆粕(芳纶浆粕，PPTAPulp)缩聚反应过程的影响。利用PPTA刚性分子发生逐步缩聚反应的缩聚模型，解释了在缩聚反应过程中，分子链的取向是提高PPTA相对分子质量的必要条件。实验结果表明，提高剪切速率有利于PPTA分子沿流动方向取向，从而提高缩聚反应速率以及芳纶浆粕的相对分子质量，同时还有利于提高浆粕的长径比(L／D)。     

沉析法制备聚丙烯腈浆粕的研究

采用沉析法制备得到了高比表面积的聚丙烯腈（PAN）腈纶浆粕，系统地研究了沉析过程中各工艺参数对PAN浆粕成形的影响。对制备的浆粕进行了表面形貌的扫描及比表面积的测定，结果表明，提高剪切强度、延长剪切时间、提高浆液和凝固浴温度对PAN浆粕的成形有利。     

接枝率对N-烷基化聚对苯二甲酰对苯二胺性能的影响

聚对苯二甲酰对苯二胺(PPTA)纤维是一种高性能纤维,因难溶于普通有机溶剂而使其应用受到较大程度限制。针对PPTA溶解性差的的缺陷,本文通过控制溴乙烷的量制备了不同接枝率的N-烷基化PPTA聚合物,并系统地研究了接枝率对PPTA结构和性能的影响。分别用傅立叶红外光谱分析(FT-IR)、核磁共振(NMR)、凝胶色谱仪(GPC)、基质辅助激光解吸电离飞行时间质谱(MALDI-TOF-MS)、X射线衍射仪(XRD)和热重分析(TGA)对PPTA聚合物和N-烷基化PPTA聚合物进行性能测试与分析,结果表明:烷基化反应不会破坏PPTA主链,随着接枝率越高,N-烷基化PPTA聚合物溶解性越好,但结晶度和热稳定性受到一定影响。越高接枝率对N-烷基化PPTA的溶解性的改善效果越好,这有助于工业上准确测试分子量及分子量分布。     

SiC-Sialon复相材料制备及高温性能

利用凝胶注模成型工艺和压力成型工艺制备SiC-Sialon材料.并比较两种成型方式制备的SiC-Sialon试样的高温性能及机理研究.     

硫化锌精矿无污染冶金新工艺研究──热压制团及其成型机理

开发新的制团工艺是实现硫化锌精矿直接还原蒸馏无污染冶金新工艺的关键技术之一．本文的研究结果表明，采用热压制团工艺以３８ＭＰａ的压力可制备出抗压强度达４３．５ＭＰａ的生团矿．热压制团工艺的最佳预热温度为４５０～５００℃，时间约５ｍｉｎ．最后，探讨了热压成型的机理．     

SiC-Sialon复相材料制备及高温性能

利用凝胶注模成型工艺和压力成型工艺制备SiC-SiMon材料。并比较两种成型方式制备的SiC-SiMon试样的高温性能及机理研究。     

《东华大学学报(自然科学版)》第31卷总目次(2005年第一期第~六期)

氨解法制备立方相氮化铌纳米粉体……………………………………………………………李耀刚高濂朱美芳(1 1)连续混沌系统的模糊建模…………………………………………………………………………………范丹丹方建安(1 6)氨纶废丝的醇解动力学研究……………………………………………………………………王静荣钱健斌陈大俊(2 1)SPET离聚物/蒙脱土纳米复合材料的制备及表征………………………………………李阳郜君鹏马敬红,等(2 4)低温溶液缩聚法直接制备PPTA浆粕基本规律的研究…………………………………尤秀兰傅群刘兆峰,等(2 9)芳砜纶的热…     

芳纶纤维的耐疲劳分析

本文作者主要研究在不同的纺丝成形条件下,芳纶H(PPTA)纤维的形态结构与耐疲劳性的关系,从工艺及生产技术的角度探索改进耐疲劳性的各种因素。研究证明,在某一浓度,某一纺速和一定的皮层含量时其耐疲劳性能较佳。     

用均匀设计对PPTA纺丝工艺进行优化

在聚对苯二甲酰对苯二胺(PPTA)纤维纺丝工艺初步成形的基础上,利用均匀设计法建立回归模型.以纤维断裂强度作为质量指标,对PPTA纺丝过程中的喷出速度、拉伸倍数、卷绕速度3个主要工艺参数进行了优化,力图用最少的试验次数确定最佳的工艺条件.通过计算得到回归方程,经过残差分析可知该方程的可靠性较高.利用SUMT外点法寻优,计算得到PPTA纺丝的最佳工艺条件:喷出速度为26.68m/min,拉伸倍数为7.76倍,卷绕速度为208.34m/min,则PPTA纤维的理论断裂强度为35.67cN/dtex.     

A STUDY OF THE MORPHOLOGY OF POLY(1,4 PHENYLEN TEREPHATHALAMIDE) (PPTA) PULP

The morphology of PPTA pulp is investigated by means of optical microscope and scanningelectron microscope (SEM). It shows that PPTA pulp has feather-like branch, needle point-likeend, and irregular cross-section, which are very important for PPTA pulp as a reinforcer. Theseparation limitation of PPTA pulp is also investigated from both torn and brittle break cross-sec-tion. A packing mechanism is proposed to illustrate the microfibril packing in the gel system.     

芳纶浆粕与尼龙-6复合体的力学性能

对芳纶浆粕与尼龙-6的复合体进行了初步的研究,通过把不同量的芳纶浆粕与尼龙-6复合的方法,研究芳纶浆粕含量与复合体力学性能的关系.并尝试了对芳纶浆粕进行表面处理,也对浆粕/尼龙-6体系的填充物进行了讨论.     

Surface Modification of Poly-(p-Phenylene Terephthalamide) Pulp with a Silane Containing Isocyanate Group for Silicone Composites Reinforcement

A silane containing isocynate groups(3-(trimethoxysilyl) propyl cyanic acid ester,NCO) associated with hexamethyldisilazane(HDMS) is used to modify the surface of poly-(p-phenylene terephthalamide)(PPTA) pulps. As concerns surface chemistry,Attenuated Total Reflection Flourier Transformed Infrared Spectroscopy(ATR FT-IR) and X-ray photoelectron spectroscopy(XPS) confirm that NCO associated with HDMS silylated PPTA pulp surface successfully. While the modified PPTA pulps are used as reinforcing fillers for silicone composites,the dispersibility and storage stability of the composites are improved as Mooney testing indicated. The silicone composites filled with modified PPTA pulps present a higher tensile strength and much higher broken elongation(3.30 MPa and 166.54%) than that with unmodified pulps(3.08 MPa and 68.47%),respectively.     

Surface modification of poly-(<Emphasis Type="Italic">p</Emphasis>-phenylene terephthalamide) pulp with a silane containing isocyanate group for silicone composites reinforcement

A silane containing isocynate groups (3-(trimethoxysilyl) propyl cyanic acid ester, NCO) associated with hexamethyldisilazane (HDMS) is used to modify the surface of poly-(p-phenylene terephthalamide) (PPTA) pulps. As concerns surface chemistry, Attenuated Total Reflection Flourier Transformed Infrared Spectroscopy (ATR FT-IR) and X-ray photoelectron spectroscopy (XPS) confirm that NCO associated with HDMS silylated PPTA pulp surface successfully. While the modified PPTA pulps are used as reinforcing fillers for silicone composites, the dispersibility and storage stability of the composites are improved as Mooney testing indicated. The silicone composites filled with modified PPTA pulps present a higher tensile strength and much higher broken elongation (3.30 MPa and 166.54%) than that with unmodified pulps (3.08 MPa and 68.47%), respectively.     

芳纶Ⅱ帘线结构与其力学性能关系的实验研究

本文通过对芳纶Ⅱ帘线拉伸断裂强度和模量与其捻度、初复捻度比关系的研究,得出了芳纶Ⅱ纤维的加捻规律和帘线拉伸断裂强度与其捻度的经验关系式,为芳纶Ⅱ纤维的应用加工提供了帘线结构参数及计算依据.     

芳香族聚酰胺（PPTA）纤维弯曲疲劳的形变和断裂机理

普通PPTA纤维和改性PPTA纤维具有近似的应力应变的曲线,但后者的弯曲疲劳寿命比前者要长的多。在SEM下观察了弯曲疲劳过程的形态变化,发现该过程主要是结构沿纤维长度分裂即原纤化过程。改性PPTA纤维对原纤化的阻抗显著地大于普通PPTA纤维。粉碎降解和低温断裂的结果也得出类似结果。表明大分子间结合力在PPTA纤维弯曲疲劳中起很重要的作用。弯曲疲劳作用被归结为对材料拉伸和压缩的复合作用。拉伸PPTA纤维的动态观察得出,拉伸或压缩纤维将出现剪切带或滑移带,它们引发纤维原纤间的分离。剪切屈服是其主要形变机制。PPTA纤维弯曲疲劳过程如下：重复弯曲引起材料局部区域的剪切屈服,出现剪切带,并随之发生结构分裂,纤维广泛地原纤化,最后原纤和原纤束相继破坏,纤维最终断裂。     

Effect of Added Poly （vinyl pyrrolidone） during Condensation on Properties of Poly（p-phenylene terephthalamide）Pulp

Poly (p-phenylene terephthalamide) (PPTA) pulp was prepared by polycondensation of the p-phenylene diamine (PPDA) with terephthaloyl chloride (TPC) in the completely anhydrous solvent system of N-methyl pyrrolidone (NMP) having calcium chloride, in the presence of poly (vinyl pyrrolidone) (PVP) having a viscosity average molecular weight lower than 40 000. It was confirmed that the polycondensation could be accelerated, the inherent viscosity of the polymer could be increased, and the polymers could be fibrillated more easily by the addition of the PVP. FTIR and X-ray spectra proved that PVP had not combined into molecular chains of the resultant PPTA pulps. The morphology of the resultant pulps, the effect of viscosity average molecular weight, amount and adding mode of PVP on inherent viscosity, specific surface area,and mean length of the resultant pulps were discussed in detail. And the friction and wear properties of the compound reinforced by the resultant pulps were simply investigated.     

Modification of PPTA by Adding N, N''-piperazineydiamine

High viscous PPTA copolymer is prepared by low temperature solution copolycondensation of terephth aloylchloride, p-phenylenediamine and p, p'-diamino phenylpiperazine in the NMP-CaCI2 solvent system. The inherent viscosity of all copolymers is more than 5. If more quantity of 3rd monomer is introduced into the macromolecular chain, the inherent viscosity becomes higher. The copolymer's ash content is less than 1 000 μg/g. The heat durability of copolymer is close to that of PPTA, and its dissolubility is superior to that of PPTA.