抗紫外老化聚对苯撑苯并二噁唑(PBO)纤维的制备与表征

通过化学添加2,5-二羟基对苯二甲酸(DHTA)共聚,以及添加金红石型纳米TiO2物理共混的方法,制备了聚对苯撑苯并二噁唑(PBO)的抗紫外改性纤维.考察了纤维的力学性能、特性粘度及表面形貌在紫外老化过程中的变化,并结合PBO纤维紫外加速老化后的红外分析,对PBO纤维的光老化机理进行了初步研究.结果表明,本实验所制备的DHPBO纤维以及DHPBO/n-TiO2纤维的抗紫外老化能力明显高于PBO纤维,并且金红石型纳米TiO2对PBO的抗紫外改性效果要优于有机紫外吸收剂(2,2'-(1,2-乙烷二基)双(4,1-亚苯基)双苯并噁唑).     

高性能PBO纤维的成型、性能改善及其应用研究北大核心CSCD

聚苯撑苯并二噁唑(PBO)纤维具有超高强度和模量、优异的耐热性和阻燃性,是一种在国防军工、航空航天等领域有重要应用价值的有机高性能纤维。本文综述了国内外PBO纤维的发展历程、纤维的性能,重点介绍了制备高分子量PBO聚合物和纺制高性能PBO纤维的关键技术和先进工艺,提供了改善PBO纤维界面粘结性能、压缩性能和光老化稳定性能的不同技术途径。结果表明:PBO聚合只有多种因素包括单体、工艺、设备等同时优化才能获得高分子量的PBO聚合物,利用双螺杆挤出机同时完成聚合和液晶纺丝成型是工业化连续生产高性能PBO纤维的先进技术路线;通过在PBO大分子链上引入离子基团或双羟基能显著提高PBO纤维与环氧树脂的界面粘结强度,双羟基的存在能使PBO大分子链间建立氢建相互作用从而也提高了PBO纤维的压缩性能,双羟基单体特有的紫外吸收性能更是有效地改善了PBO纤维的光稳定性;在PBO聚合时添加光吸收剂,或在PBO纤维表面涂覆聚酰亚胺都是改善PBO纤维光稳定性的有效方法。     

2-（4-甲氧羰基苯基）-5-硝基-6-羟基苯并噁唑的热分解机理及动力学

顺式聚对苯撑苯并二噁唑(cis-poly-paraphenyl enebenzobisoxazole,简称PBO)引起了人们的重视[1-3]。由PBO制得的高性能纤维的商品名为Zylon[2],Zylon不仅具有高的机械强度,而且具有高的热氧化稳定性[2,4-5]。PBO纤维和PBO复合材料在宇航、武器装备等领域中有广阔的应用前景[1-     

PBO纤维界面粘结性能的研究进展

介绍了PBO(聚对苯撑苯并双噁唑)纤维的结构与性能,并针对该纤维作为复合材料增强体与树脂界面粘结性差的特点,评述了PBO纤维表面改性技术中的化学法、共聚改性、偶联剂处理、等离子处理、电晕处理和辐射处理法的研究进展,并比较了各种方法的改性效果及各自优缺点。     

连续纤维增强含二氮杂萘酮联苯结构聚芳醚砜酮树脂基复合材料的界面

利用射频感性耦合冷等离子体(ICP)处理技术改性连续纤维表面,分别采用X射线光电子能谱(XPS)、原子力显微镜(AFM)及动态接触角分析(DCA)系统研究了等离子体处理时间、放电气压、放电功率等工艺参数对连续碳纤维、芳纶纤维和对亚苯基苯并二噁唑(PBO)纤维的表面化学成分、表面形貌、表面粗糙度及表面自由能的影响.研究结...     

复合溶胶-凝胶法改善PBO纤维的光稳定性

分别以钛酸正丁酯(C16H36O4Ti)、醋酸(CH3COOH)、盐酸(HCl)、丙基三甲氧基硅烷(KH560)、苯基三甲氧基硅烷(Ph-TMS)、甲醇(CH3OH)和去离子水(H2O)为原料,氨水(NH3·H2O)为催化剂,分别采用溶胶-凝胶法和复合溶胶-凝胶法涂覆制备防老化聚亚苯基苯并二唑(PBO)纤维。通过粒度分析验证了纳米溶胶的成功制备,通过EDS能谱、SEM扫描电镜、接触角测定等分析测试PBO纤维表面的化学组成与物理性能,验证防老化PBO纤维的成功制备。以拉伸强度测试、SEM扫描电镜和表面接触角表征PBO纤维的防老化性能。结果表明:在氙灯耐气候试验箱经历130h的老化后,与未经过涂覆的PBO原纤相比,采用纳米TiO2水溶胶-凝胶法涂覆的PBO纤维拉伸强度保持率只提高了5%,利用纳米有机硅溶胶-凝胶法涂覆的PBO纤维拉伸强度保持率可提高10%,而经过纳米TiO2和有机硅溶胶-凝胶法涂覆的PBO纤维,拉伸强度保持率提高了27%,且老化后的纤维表面保持得非常完整。     

复合溶胶-凝胶法改善PBO纤维的光稳定性

分别以钛酸正丁酯(C_(16)H_(36)O_4Ti)、醋酸(CH_3COOH)、盐酸(HCl)、丙基三甲氧基硅烷(KH560)、苯基三甲氧基硅烷(Ph-TMS)、甲醇(CH_3OH)和去离子水为原料,氨水(NH_3·H_2O)为催化剂,采用溶胶-凝胶法和复合溶胶-凝胶法分别涂覆制备防老化聚亚苯基苯并二噁唑(PBO)纤维。通过粒度分析验证了纳米溶胶的成功制备,通过EDS能谱、SEM扫描电镜、接触角测定等手段分析测试PBO纤维表面的化学组成与物理性能,验证防老化PBO纤维的制备。以拉伸强度测试、SEM扫描电镜和表面接触角表征PBO纤维的防老化性能。结果表明:在氙灯耐气候试验箱经历130 h的老化后,与未经过涂覆的PBO原纤相比,采用纳米TiO_2水溶胶-凝胶法涂覆的PBO纤维拉伸强度保持率只提高了5%,利用纳米有机硅溶胶-凝胶法涂覆的PBO纤维拉伸强度保持率可提高10%,而经过纳米TiO_2和有机硅复合溶胶-凝胶法涂覆的PBO纤维,拉伸强度保持率提高了27%,且老化后的纤维表面保持得非常完整。     

提高PBO纤维/环氧树脂复合材料界面结合的研究

本文采用表面化学蚀刻与溶胀法结合、化学偶联法与氩气低温等离子体表面处理技术结合的方法对聚苯撑苯并二。唑（PBO）纤维进行表面改性。探讨了不同改性方法对纤维表面性能的影响。同时，采用FTIR和SEM等方法对处理前后纤维表面化学结构及形态进行了表征。     

PBO-b-ABPBO多嵌段共聚物的制备及其性能

采用反应挤出法制备了一系列不同组成的聚(对亚苯基苯并二唑/3-氨基-4羟基苯甲酸盐酸盐)(PBO-b-ABPBO)多嵌段共聚物,用傅立叶红外(FT-IR),广角X射线衍射(WXRD)对其结构进行了表征,并用热重分析(TGA)对其热性能进行分析,另外用压差式毛细管流变仪对PBO-b-ABPBO溶液的剪切流变性能进行了研究.结果表明:PBO-b-ABPBO溶液在流动性和可纺性方面较PBO溶液有较大改善,尽管PBO-b-ABPBO纤维的热性能和力学性能比PBO纤维略有下降.     

多聚磷酸/乙酸体系对PBO纤维表面改性的研究

采用多聚磷酸/乙酸体系并结合偶联剂处理方法对PBO纤维表面进行化学改性,采用扫描电镜和液滴形状法对处理前后纤维表面形态结构和纤维表面亲水性进行了表征,通过单丝拔出试验测定了改性前后PBO纤维与环氧树脂基体的界面剪切强度。利用X光电子能谱和热重分析等方法对纤维表面元素组成和热稳定性进行了分析。研究发现,多聚磷酸/乙酸体系偶联剂的方法改性后PBO纤维表面亲水性明显增强,与水的接触角从大于90°下降到42.8,°PBO纤维/环氧树脂的界面剪切强度较未处理样品提高了45%。     

The synthesis,characterization, and crystal structures of poly(2,6‐naphthalenebenzobisoxazole) and poly(1,5‐naphthalenebenzobisoxazole)

The rigid‐rod polymers, poly(2,6‐naphthalenebenzobisoxazole) (Naph‐2,6‐PBO) and poly(1,5‐naphthalenebenzobisoxazole) (Naph‐1,5‐PBO) were synthesized by high temperature polycondensation of isomeric naphthalene dicarboxylic acids with 4,6‐diaminoresorcinol dihydrochloride in polyphosphoric acid. Expectedly, these polymers were found to have high thermal as well as thermooxidative stabilities, similar to what has been reported for other polymers of this class. The chain conformations of Naph‐2,6‐PBO and Naph‐1,5‐PBO were trans and the crystal structures of Naph‐2,6‐PBO and Naph‐1,5‐PBO had the three‐dimensional order, although the axial disorder existed for both Naph‐2,6‐PBO and Naph‐1,5‐PBO. Naph‐2,6‐PBO exhibited a more pronounced axial disorder than Naph‐1,5‐PBO because of its more linear shape. The repeat unit distance for Naph‐2,6‐PBO (14.15 Å) was found to be larger compared with that of Naph‐1,5‐PBO (12.45 Å) because of the more kinked structure of the latter. The extents of staggering between the adjacent chains in the ac projection of the crystal structure were 0.25c and 0.23c for Naph‐2,6‐PBO and Naph‐1,5‐PBO, respectively. Naph‐1,5‐PBO has a more kinked and twisted chain structure relative to Naph‐2,6‐PBO. The kinked and twisted chain structure of Naph‐1,5‐PBO in the crystal seems to prevent slippage between adjacent chains in the crystal structure. The more perfect crystal structure of Naph‐1,5‐PBO may be due to this difficulty in the occurrence of the slippage. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1948–1957, 2006     

Hydrolytic stability of polybenzobisoxazole and polyterephthalamide body armor

Previous work conducted at the National Institute of Standards and Technology (NIST) to investigate the field failures of soft body armor containing the material poly(p -phenylene-2,6-benzobisoxazole), or PBO, revealed that this material was susceptible to hydrolysis, and a mechanism of this hydrolysis was proposed. In this work, viscometric estimations of the molar mass of environmentally conditioned PBO are used to support a previously proposed mechanism of PBO hydrolysis. Results with PBO were compared with poly(p-phenylene terephthalamide), or PPTA, which has been used in body armor applications for more than 30 years. Losses in tensile strength were found to correspond to a reduction in molar mass for PBO. This indicates that chain scission due to complete hydrolysis is occurring in this material. Similar trends were observed for PPTA, but the relationship between molar mass reduction and losses in tensile strength was not as evident for this material. Confocal microscopy, mechanical properties measurements, and molecular spectroscopy are used to further investigate the degradation of both PBO and PPTA.     

In situ polymerization and characterization of graphene oxide‐co‐poly(phenylene benzobisoxazole) copolymer fibers derived from composite inner salts

A facile and efficient strategy for preparing well dispersed graphene oxide (GO)‐co‐Poly(phenylene benzobisoxazole) (PBO) copolymer fibers was carried out by direct in situ polycondensation of composite inner salts. The composite inner salts were achieved to improve the dispersivity, solubility, reactivity, and interfacial adhesion of GO in PBO polymer matrix. The structure and morphology of GO‐co‐PBO copolymer fibers have been characterized. It was demonstrated that GO were covalently incorporated with PBO molecular chains and dispersed considerably well in PBO fiber even the GO reach to 3 wt %. Meanwhile, the tensile modulus, tensile strength and thermal stability of GO‐co‐PBO copolymer fibers increased considerably with GO. The mechanism and theoretical calculation of GO enhanced PBO fiber were also discussed. The main reasons for the improvement on performance of PBO fiber should be attributed to good dispersion GO in PBO matrix and covalent bonding networks at the interface between GO and PBO molecular chains. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Resonance raman spectra of poly‐(p‐phenylenebenzobisoxazole), poly‐(p‐phenylenebenzobisthiazole), and poly(pyridobisimidazole)

Resonance Raman spectra of poly(p‐phenylenebenzobisoxazole) (PBO), poly(p‐phenylenebenzobisthazole) (PBZT), and poly(pyridobisimidazole) (PIPD) were measured. In the case of PBO, no large dependence on wavelength of excited laser can be observed, whereas in the cases of PBZT and PIPD, the spectra depends on wavelength of excited laser. This difference may be attributed to the colors of the samples: PBO is gold, and PBZT and PIPD are metallic blue, which show the different conjugated states. The spectra of PBO are rather simpler than those of PBZT and PIPD. This is considered to be reflected by the fact that only a chain passes through the unit cell of PBO, while two chains pass through the unit cell of PBZT and PIPD. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1791–1793, 2001     

An analysis of deformation process on poly‐p‐phenylenebenzobisoxazole fiber and a structural study of the new high‐modulus type PBO HM+ fiber

This study is concerned with fiber structure of new high‐modulus type PBO fiber. Crystal modulus and molecular orientation change with stress was surveyed. Standard‐modulus type PBO (AS) fiber has hysteresis effect to applied stress while high‐modulus type PBO (HM) fiber shows reversible change. In order to raise actual PBO fiber modulus higher, nonaqueous coagulation process was adopted with conventional heat treatment. The fiber (HM+) so made gives 360 GPa in the Young's modulus and an absence of small‐angle X‐ray scattering pattern that is characteristic for aqueous‐coagulated PBO fiber with heat treatment (Zylon™ HM). The crystal structure form and crystal size for the HM+ fiber are the same as those of the HM fiber. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1605–1611, 2000     

Novel synthesis of high‐molecular‐weight prepolymer of poly(p‐phenylene benzoxazole) in ionic liquids

Using ionic liquids (ILs) as the reaction solvent for the synthesis of prepolymer polyamide of poly(p‐phenylene benzoxazole) (PBO) was investigated. The optimum condition of prepolymer preparation was determined in ILs. A series of 1,3‐dialkylimidazolium ILs were used to be the reaction media of the polycondensation. The relationship between the molecular weight of prepolymer and the structure of ILs was analysed by changing the structure of the cation and species of anion of ILs. In order to prove the feasibility of the transformation, the prepolymer was used to prepare PBO in polyphosphoric acid media, and the conversion process was analyzed. The spinnability of the PBO solution was explored by the preparation of PBO fibers. The basic mechanical properties of PBO single fiber were tested. In a word, using 1,3‐dialkylimidazolium ILs as the reaction solvents was feasible for the synthesis of high‐molecular‐weight PBO prepolymer, which could be a promising PBO preparation method.     

Hyperbranched polybenzoxazoles incorporated polybenzoxazoles for high‐performance and low‐K materials

This paper reports an effective approach for the fabrication of low‐k polybenzoxazole (PBO) by covalent incorporation of hyperbranched PBO (HBPBO). Soluble o‐aminophenol‐terminated HBPBO was first synthesized by a one‐pot polycondensation, then covalently bonded to poly(hydroxyamide) ended with carbonyl chloride groups, PBO was finally obtained by thermal conversion of the precursor polymers. It was demonstrated that the thermal stability of PBO was not influenced by the incorporation of HBPBO due to their similar chemical compositions, while the glass transition temperature, elastic modulus and hardness were improved because of the linking effects of HBPBO to linear PBO chains. The dielectric constant of PBO was significantly reduced due to the disturbed chain packing of PBO by the globular HBPBO, and the intrinsic cavities in HBPBO, which increased free volume in the materials. Moreover, the material also exhibited reduced coefficient of thermal expansion as compared to neat PBO and low water absorption. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1623–1632     

Poly(p-Phenylenebenzobisoxazole) fiber with polyphenylene sulfide pendent groups

Poly(p-phenylenebenzobisoxazole) (PBO) fiber with polyphenylene sulfide (PPS) pendent groups was made to improve PBO fiber compressive strength by crosslinking. PPS moieties allowed the polymeric network to crosslink at heat-treatment temperatures at which PBO does not thermally degrade. PBO-PPS fiber heat-treated for 30 s at 600°C did not dissolve or break up in methanesulfonic acid. Compressive strength of crosslinked fiber was about 20% better than that of unmodified PBO fiber. In another experiment, 10 mol % of 2,5-diphenylsulfideterephthalic acid was incorporated into PBO fiber. The side chain of one phenyl sulfide unit was too short to enhance crosslinking, and the fiber had about the same compressive strength as unmodified PBO fiber. © 1995 John Wiley & Sons, Inc.     

PBO聚合物紫外吸收光谱中环境因素影响的理论研究

芳杂环液晶高分子聚对亚苯基苯并二噁唑（PBO, poly(p-phenylene-2,6- benzobisoxazole)）的共轭平面结构赋予其光电性能而备受关注.实验结果表明其光电性能受其所处环境状态影响. 通过量子化学计算研究发现,PBO无论固态还是溶液状态的最大紫外吸收均较其本征值有所红移.对PBO二聚体模型以及其在强质子酸中所具有的质子化形态模型的紫外吸收光谱计算模拟的结果表明,PBO聚集态时的分子间相互作用,以及溶液中质子化效应均导致红移.质子化模型所得紫外吸收光谱能很好地阐释溶液中具有精细结构实测的紫外吸收光谱.