PPPTA共缩聚改性研究现状

改善对位芳纶(PPTA)性能的有效方法是在聚合体系中加入第三第四单体进行共缩聚改性。本文主要介绍了在聚合物主链上引入柔性结构单元,刚性结构单元,取代对苯、间苯结构,二炔类结构,N取代结构,超支化结构等改性方法的研究现状,并评价了各种方法的改性效果。     

PPTA共缩聚改性研究现状

改善PPTA性能的有效方法是在聚合体系中加入第三、四单体,进行共缩聚。文中介绍了在主链中引入芳香醚类结构,取代对苯和间苯结构,萘基、蒽基、联苯基等刚性结构,脂肪族柔性结构,杂环结构及二炔类结构和N取代结构等的改性研究现状,并评价了各种方法的改性效果。     

聚苯并双噁唑类聚合物的合成及改性

简述了聚对苯撑苯并双(?)唑(PBO)的合成方法,详述了直链烯烃型、稠环芳烃型、联苯取代基型、杂环型聚苯并双(?)唑类聚合物的合成方法。综述了等离子体处理法、偶联剂处理法、电晕处理法等一系列PBO纤维表面改性技术的研究进展,通过介绍PBO／碳纳米管复合材料和PBO／粘土复合材料的合成技术,简析了PBO的纳米改性的研究。指出聚苯并双(?)唑聚合物研究将集中在合成高相对分子质量的聚合物合成技术,通过纳米改性及表面改性提高其性能,扩大应用领域。     

聚乳酸材料耐热改性研究进展

介绍了聚乳酸材料的合成方法,综述了共混改性、复合改性、接枝共聚、分子主链中引入耐热结构单元等聚乳酸改性技术,并对聚乳酸的发展前景作了展望。     

羧基改性聚乙烯醇的制备及水溶性研究

通过丙烯酸(AA)与乙酸乙烯酯(VAc)共聚进而醇解的方法合成出具有高醇解度、低结晶度的丙烯1酸改性聚乙烯醇。通过FT-IR和H-NMR对聚合物的化学结构进行了表征;通过XRD、UV-Vis、剪切流变测试等手段研究了丙烯酸结构单元含量对改性PVA的结晶性能、水溶性能和溶液表观黏度的影响。结果显示,通过引入适量丙烯酸结构单元,可降低PVA结晶度,提高PVA水溶性,增强PVA水溶液表观黏度的剪切稳定性。     

测定蛋白质氨基置换度的三种方法

明胶蛋白质氨基置换度(改性度)的测定方法较多,在PA胶等改性胶的研究中已作过研究,并已在文献上发表。本文摘编了某些作者的工作,比较了确定蛋白质-氨基取代程度的三种方法。这些方法被应用于明胶的苯磺酰基类衍生物。甲醛滴定法和茚三酮比色分析法通常适用于可溶性蛋白质及其可溶性衍生物。当取代试剂含发色基团时,分光光度计法也适用于这些物质。使用这种方法时,蛋白质中的酪氨酸含量必须低或不与试剂反应,或者取代分子的发色团必须在酪氨酸吸收范围内无光吸收性。前两者之间有着很好的一致性,而第三种方法在上述条件均满意的情况下也能与前两者相一致。     

PBO纤维及其改性的研究进展

简述了聚对苯撑苯并双噁唑(PBO)纤维的结构与性能;详述了PBO纤维的改性研究进展。PBO纤维的改性主要是改善其抗压性能和表面粘结性能。提高微纤间相互作用或交联等方法可提高PBO纤维的压缩强度;通过酸处理、偶联剂处理、等离子体处理及电晕处理等方法可提高PBO纤维的表面粘结性能。指出表面改性仍将是PBO纤维改性研究的重点。     

全氟异丙基苯衍生物的合成及其在新农药创制中的应用

对全氟异丙基取代的苯胺、苯酚、苯甲酸以及苯肼等各类全氟异丙基苯衍生物的合成方法做了简要的介绍,阐述了全氟异丙基苯衍生物在新农药创制中的重要应用,并举例介绍了几类含有全氟异丙基苯结构的创新农药.     

天然二苯乙基类化合物的结构、来源及药理活性研究进展

二苯乙基类化合物是两个苯甲基结构单元通过甲基的C-C单键连接而成的一类重要化合物。其广泛分布于不同的植物中,结构类型多样,并具有调节植物生长、抗氧化、抗菌、抗病毒活性和细胞毒活性等多种生物活性而成为研究的焦点。总结了天然二苯乙基类化合物的结构、来源及药理活性等的研究进展,旨在为二苯乙基类化合物的深入研究提供参考。     

PBO纤维表面改性技术的研究进展

介绍了聚对苯基苯并二噁唑(PBO)纤维的合成、结构与性能;同时,综述了目前常见的对PBO纤维表面改性方法的研究进展,如以等离子体处理、辐射处理和电晕处理等为代表的物理方法,以酸处理、偶联剂改性、共聚改性和酶处理等为代表的化学方法。     

Surface modification of aromatic polyamide film by remote oxygen plasma

Surface modification of poly(p-phenylene terephthalamide) (PPTA) film by a remote oxygen plasma treatment has been investigated from a viewpoint of comparison with a direct oxygen plasma treatment. We call the modification procedure in a space far away from the oxygen plasma zone “the remote oxygen plasma treatment,” and the modification procedure in a space just in the oxygen plasma zone (a conventional oxygen plasma treatment) “the direct oxygen plasma treatment.” In a space far away from the plasma zone, oxygen radicals rather than electrons and oxygen ions are predominant, and the PPTA film can be modified by the remote oxygen plasma treatment into a hydrophilic surface without heavy degradation of the PPTA film. The PPTA film surfaces modified by the remote oxygen plasma treatment were analyzed with contact angle measurement, scanning microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 831–840, 1997     

Surface modification of aromatic polyamide film by aminoethanethiol solution for silicon rubber composites

The surface modification of poly(p-phenylene terephthalamide) (PPTA) film with 2-aminoethanethiol (AET) to adhere to silicon rubber was investigated. The combination of the AET treatment and the silane coupling treatment is an effective surface modification of the PPTA film for this adhesion. The x-ray photoelectron spectroscopy (XPS) analyses show that the AET treatment does not generate sulfur functionalities at the surface of the PPTA film but does generate oxygen functionalities. In the AET treatment process, a part of the amide groups near the surface of the PPTA film is hydrolyzed to form carboxylic acid groups and amino groups. The oxygen functionalities are condensed at the film surface, and nitrogen functionality is diluted at the film surface. The C(O)O moiety at the PPTA film surface may be a key factor for the adhesion with silicon rubber. The C(O)O moiety is mobile from the bulk of the PPTA film to the film surface. Hot water treatment of the original PPTA film makes the impossible adhesion with the silicon rubber possible. The hot water treatment, however, is not as powerful a surface modification as the AET treatment. © 1995 John Wiley & Sons, Inc.     

Surface modification of Kevlar® fiber by a combination of plasma treatment and coupling agent treatment for silicone rubber composite

To improve the adhesion between poly(p-phenylene terephthalamide), PPTA, fiber and silicone rubber, the surface modification of PPTA was investigated. Combining plasma treatment and coupling agent treatment with the silicone adhesive was found to be effective in improving adhesion. The combination process made the pull-out force of the PPTA yarn/silicone rubber composite 2.5 times higher, compared with the plasma treatment or the coupling agent treatment alone. The plasma treatment led to the elimination of carbonized layer from the PPTA yarn surface and the formation of oxygen functionalities including C-O and C=O groups. The elimination of the carbonaceous deposits from the PPTA surface and the interaction between the silicone adhesive and the oxygen functionalities created by the plasma treatment contribute to the improvement of adhesion with silicone rubber.     

沉析法制备聚对苯二甲酰对苯二胺浆粕成形机理的探讨

在电子显微镜和光学显微镜观察的基础上,对沉析法制备聚对苯二甲酰对苯二胺(PPTA)浆粕的成形机理进行探讨:PPTA/H2SO4溶液的小液滴在剪切流动场作用下被逐渐拉长,随着凝固液扩散到PPTA/H2SO4溶液液滴中,当达到一定的凝固条件时,形变就被凝固下来形成PPTA纤维,在高速搅拌作用下,发生原纤化作用而形成PPTA浆粕。     

Polymer composite of rigid and flexible molecules: Blend systems of poly(p-phenylene terephthalamide) and ABS resin

Homogeneous coagulant of poly(p-phenylene terephthalamide) (PPTA) and ABS resin was obtained by pouring the dimethylsulfoxide solution of N-sodium PPTA and ABS into acidic water. Transmission electron microscopic observation proved that PPTA was dispersed in the matrix in a form of microfibril with a diameter of 10–30 nm. The T_g of the resin component in ABS shifted to higher temperatures with increasing fraction of PPTA. Stress-strain behavior of the polymer composite showed increased tensile modulus and strength with addition of PPTA. The transition temperature from brittle to ductile fracture, however, shifted to higher temperature resulting in lower extensibility. Incorporation of the block copolymer of PPTA and polybutadiene into ABS improved the ultimate extensibility, i.e., increased toughness was provided compared with the simple composite systems of ABS and PPTA microfibrils. Scanning electron microscopic observation showed that the polymer composite made with the block copolymer generated many crazes upon deformation, while the composite with PPTA homopolymer fractured without remarkable craze formation. Thus, a new type of thermoplastic with improved mechanical properties was obtained by use of PPTA block copolymer as compatibilizer.     

TPC溶液加料低温溶液缩聚合成PPTA的研究

本文详细研究了采用对苯二甲酰氯(TPC)溶液加料(双溶液法)低温溶液缩聚合成聚对苯二甲酰对苯二胺(PPTA)的各种工艺条件对产物对数比浓粘度的影响。结果表明,盐的用量、吡啶的用量和单体浓度与TPC粉末加料具有相同的规律性。由于TPC溶液加料工艺的影响,单体摩尔比、TPC分步加料的使用、溶液放置时间及溶剂在TPC和对苯二胺(PPD)溶液配制时的分配比例等具有其特殊的规律性。在优选的条件下,TPC溶液加料工艺和固体粉末加料工艺一样,可以获得较高对数比浓粘度的PPTA。     

Phase behavior and mechanical properties of poly-p-phenylene terephthalamide/amorphous nylon molecular composites

Poly(p-phenylene terephthalamide) (PPTA)/amorphous nylon (AN) molecular composites were prepared from sulfuric acid solution by rapidly coagulating in distilled water. The regenerated films appear homogeneous and transparent. However, the rod-like and flexible macromolecules are probably entrapped in a single phase during rapid coagulation, thus thermodynamically unstable and undergoing phase segregation upon thermal treatment. The miscibility between PPTA/AN was identified by a dielectric relaxation method. Phase behavior and kinetics of phase separation in PPTA/AN mixtures were thoroughly investigated by time-resolved light scattering as well as optical microscope. A pseudo phase diagram reminiscent of a lower critical solution temperature (LCST) was established by a cloud point measurement. Several temperature-jump experiments were undertaken from ambient to a two-phase temperature region. The low PPTA content molecular composites were prepared by coagulating in a non-solvent, then by compression molding below the phase separation temperatures. The 30 wt% PPTA molecular composite exhibits over three-fold increase in tensile modulus relative to that of the neat AN, however, there is little or no improvement in the tensile strength. On the other hand, by a slight addition of AN into PPTA, the tensile and compressive failures of spun fibers may be improved.     

Preparation and properties of graft and block copolymers of poly(p-phenylene terephthalamide) with polybutadiene

Graft copolymers of polybutadiene (PBD) onto poly(p-phenylene terephthalamide) (PPTA) were prepared by the nucleophilic substitution of N-metalated PPTA with telechelic PBD having bromide end groups. Block copolymers were synthesized by the condensation reaction of telechelic PBD having acid chloride end groups with amino-group-terminated PPTA. The structure of these copolymers was identified by IR spectra. Graft and block copolymers contained PBD segments up to 85 wt % and 45 wt %, respectively. Thermomechanical analyses (TMA) proved the existence of distinctive primary absorption peak corresponding with T_g of PBD for both graft and block copolymers. The T_g's of both types of the copolymers were further ascertained by the DSC curves. TMA curves suggested that the microphase separation occurred between PPTA and PBD. The incorporation of PPTA segments into PBD increased the decomposition temperature compared with the blend polymer composed of PPTA and PBD with the same composition.