THERMAL DEGRADATION OF POLY(ARYLENE SULFIDE SULFONE)/NMETHYLPYRROLIDONE CRYSTAL SOLVATE

The thermal degradation of poly（arylene sulfide sulfone）/N-methylpyrrolidone （PASS/NMP） crystal solvate was studied by thermogravimetric analysis （TGA） and was compared with pure PASS in order to determine the way in which the formation of the crystal solvate affected the thermal properties of the polymer. The activation energy of the solid state process was determined using Kissinger＇s method, which does not require knowledge of the reaction mechanism （RM）, to be 174.18 kJ/mol which was lower than that for pure PASS （E = 214 kJ/mol）. The study of master curves together with interpretation of integral methods, allows confirmation that the thermal degradation mechanism for PASS in the crystal solvate system is a decelerated Rn type, which is a solid-state process based on a phase boundary controlled reaction, in the conversion range considered. Whereas, the pure PASS follows a decelerated Dn thermodegradation mechanism in the same conversion range.

CRYSTAL STRUCTURE AND MORPHOLOGY OF NASCENT SAMPLES OF SYMMETRIC AROMATIC POLYESTERS——Ⅰ.POLY(P-PHENYLENE TEREPHTHALATE)

The morphology and crytal structure of poly(p-phenylene terephthalate) (PPT), prepared by confined thin filmmelt (CTFMP) and solution (CTFSP) and bulk solution polymerization, were characterized by transmission electronmicroscopy, electron dimaction and molecular modeling. The unit cell is monoclinic (P2_1/a space group) with parameters a =7.89, b = 5.49, c = 12.65 A, α=γ= 90°, β=100.33°, density = 1.48 g/cm^3, the a, b and β values differing slightly from thosereported previously in the literature. A degree of variation in relative intensities of hk0 reflections in, apparently, untilted[001] ED patterns was observed from a given sample, suggesting some variation in molecular packing. ED evidence wasfound for a second phase, with [001] appearing the same as for phase Ⅱ of the related poly(p-oxybenzoate) (PpOBA)polymer. CTFMP crystals polymerized above 220℃ (up to 370℃) and CTFSP crystals polymerized at 300℃ consisted oflamellae 100-200 A thick.

The Synthesis and Characterization of High Molecular Weight Poly(phenylene sulfide/ether)

Poly（phenylene sulfide/ether） （PPSE） was synthesized from 4,4＇-dihydroxydiphenyl sulfide and 4,4＇-dichlorodiphenyl sulfide in solution by nucleophilic substitution reaction. The resulting polymer was characterized by viscosity measurement, elemental analysis, FT-IR, ^1H NMR, X-ray diffraction and thermal analysis. The results showed that the viscosities of the resulting polymer were above 0.68 dL/g, and the linear chain structure of product was confirmed. PPSE had the same reflex indices as poly（p-phenylene sulfide）, an orthorhombic crystalline with unit cell a=0.853, b=0.562, c=1.026nm. The melting temperature, glass transition temperature and initial decomposition temperature were found to be 228℃, 85℃ and 325℃, respectively. The product was soluble in common organic solvents such as NMP, N, N＇-dimethylformamide, N, N＇-dimethylacetamide and 1,2-dichloroethane.

Effect of Curing Poly(<i>p</i>-Phenylene Sulfide) on Thermal Properties and Crystalline Morphologies

Commercial poly(p-phenylene sulfide) (PPS) was thermally cured, which resulted in an increase of molecular weight due to cross-linking. Non-isothermal crystallization studies of samples cured for up to 7 days at 250?C showed a monotonous increase of crystallization temperature compared to pure PPS. However, a further increase of curing time decreased the crystallization temperature. The change in the half-crystallization time (t1/2) was similar to the crystallization temperature. Thus, the cross-linking of PPS affected crystallization behaviors significantly. To a certain extent, crosslinks acted as nucleation agents, but excessive cross-linking hindered the crystallization. Morphologies observed by polarized optical microscopy suggested that thermal curing for as little as 1 day contributed to the spherulitic structure having a smaller size, that was not observed with pure PPS.

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.

SYNTHESIS AND MORPHOLOGICAL STRUCTURE OF POLY (PHENYLENE SULFIDE AMIDE)

Poly(phenylene sulfide amide) (PPSA) has been synthesized by using sulfur as S source which reacts with dichlorobenzamide (DCBA) and alkali in polar organic solvent at the atmospheric pressure. The polymer structures were determined by elemental analysis, FT-IR and H-1-NMR. It is shown that the yielded polymer has linear structure and its structure unit is -p-C6H4-CONH -p-C6H4-S-. The polymer morphology was studied by X-ray diffraction and polarized microscopy. The results show that PPSA is a crystalline polymer and its spherulites are the aggregation of nontwisting lamella or micro-thread structure. Under shearing force, these crystals are dispersed to form micro-fibrillar structure. The decomposition kinetics of PPSA was also studied at different heating rates. The decomposition energy of PPSA is higher than that of PPS.

Preparation of Poly (Phenylene Sulfide Amide) by Sulfur Solution Route

A new process for preparing poly(phenylene sulfide amide, PPSA), which is by reaction of sulfur instead of sodium sulfide as S source with dichlorobenzamide (DCBA) and alkali in polar organic solvent at the atmospheric pressure (called sulfur solution route), is reported in the present paper. The influences of polymerization time, molar ratio of precursors, catalyst and solvent upon the polymer were investigated. To seek the best parameters of polymerization, orthogonal design was employed in the experiments. The results indicate that the molar ratio of precursors is the most significant effect on both of viscosity and yield of the polymer. The suitable parameters for preparing the related polymer are presented. The polymer was characterized by IRspectrum, 1HNMRspectrum and Raman spectrum, etc.

CRYSTAL STRUCTURE AND MORPHOLOGY OF NASCENT SAMPLES OF SYMMETRIC AROMATIC POLYESTERS——Ⅱ. POLY(p-PHENYLENE 2,6-NAPHTHALATE)

Confined thin film melt polymerization (CTFMP) of naphthalene chloride/hydroquinone (NCMQ, 1/1, molar)mixtures at polymerization temperatures (T_p) below ca. 300℃ resulted in relatively thick, elongated crystals. Polymerizationof NC/HQ above 300℃ between glass yielded well-formed lamellar crystals ca. 100 A thick. Phase Ⅰ and Ⅱ [001] EDpatterns were obtained for all T_p, the relative amount of phase Ⅰ increasing with T_p. Polymerization of naphthalenedicarboxylic acid/hydroquinione diacetate 1/1 mixtures at high T_p also yielded lamellar crystals that "curled up" off of thesubstrate. When the high temperature CTFMP polymerization was conducted between mica, aggregates of lamellae on-edgedeveloped but epitaxial growth did not occur. Epitaxial growth of lamellae between mica could be obtained, however, byconfined thin film solution polymerization, with both of the latter samples yielding apparently related ED patterns from adifferent unit cell than phase Ⅰ or Ⅱ. Fiber patterns, obtained from sheared samples, indicated considerably greater crystaldisorder than in the nascent crystals. Refinement of the phase Ⅰ unit cell parameters, based on the [001] and [01 1] EDpatterns, with modeling based on Cerius^2, suggests a monoclinic phase Ⅰ unit cell with a = 7.76, b = 5.71, c = 14.99 A, α = γ= 90°, β= 99.7°, ρ = 1.47 g/cm^3, space group P12_1/al.

Study on the behaviors of poly（p-phenylene benzobisoxazole） in coagulation

Poly（p-phenylene benzobisoxazole）（PBO） is a candidate of high performance materials for many applications. PBO materials＇ properties are considered to be closely related to their fabrication process, especially coagulation. In this paper, the coagulation effect on the chemical and microstructure of PBO was investigated with the help of a PBO model compound, 2, 2＇-（ 1,4-phenylene） bis （5-amino-6-benzoxazolole）. During coagulation, the hetero-cyclic ring of the PBO structure was experienced cleavage and even being broken down completely under some extreme conditions. Wide-angle X-ray diffraction （WAXD） analysis showed that different coagulants could cause the microstructure difference in PBO materials. In a slow coagulation process, PBO molecular chains aligned more orderly in the side-by-side direction （200）.

Mechanical Property and Crystal Structure of Poly(p-phenylene terephthalamide)(PPTA) Fibers during Heat Treatment under Tension

The relationship between property and structure of poly( p-phenylene terephthalamide)( PPTA) was investigated for the purpose of obtaining products with better performance. PPTA fiber subjected to heat treatment under different conditions was intensively studied. Simultaneous wide-angle X-ray diffraction( WAXD) technique was introduced to study the changes of crystal structure. It was found that the tensile modulus was strongly sensitive to the levels of temperature and tension. The structure parameters including crystal size and crystal orientation after heat treatment evolve similarly to the tensile modulus,indicating a direct structure-property relationship. The lattic c-dimension increases after heat treatment and is greatly affected by the tension. An optimal temperature can be found around 400 ℃,where big change can happen in the crystal structure due to α-relaxation in the crystal region as supported in dynamic mechanical analysis( DMA).

A STUDY OF PACKING STRUCTURE OF POLY(P-PHENYLENE BENZOBISTHIAZOLE)BY MOLECULAR SIMULATION

Molecular simulation technique was used in an examination of the possibilities of chain packing in the crystalline state for poly(ρ-phenylene benzobisthiazole).It has been found that one reason of hardly forming very ordered crystal of the polymer is the existence of so many stable positions of interchain interaction along chain axis.

The Synthesis and Electronic Characteristics of Poly(p-Phenylene Vinylene) Derivatives

A series of soluble poly(p-phenylene vinylene) (PPV) derivatives were synthesized through dehydrochlorination with the p-metaoxy phenol as starting materials. The electronic characteristics of PPV derivatives were studied.

多巴胺对碳纤维增强聚苯硫醚复合材料界面性能的影响

碳纤维增强聚苯硫醚复合材料(CF/PPS)因其具有优异的综合性能被广泛关注,但实际应用中发现碳纤维与聚苯硫醚的界面结合并不理想,因此,改善CF/PPS界面结合强度来提升其宏观力学性能就有着深远的理论意义和应用价值。文中基于微球脱粘技术,将具有优良黏附性的多巴胺水溶液作为界面改性剂,对纤维进行表面改性,采用微球脱粘实验和宏观拉伸等实验测试探究了不同多巴胺浓度对CF/PPS界面性能的影响。结果表明,当多巴胺浓度为2 g/L时,聚多巴胺在碳纤维表面均匀黏附,形成较好的微纳结构,涂覆效果最佳,表观界面剪切强度最大为36.09 MPa,较未改性前增加13.50%;PDA-CF2/PPS拉伸试样的断面呈现凹凸不平的形态,拔出的碳纤维上残留树脂基体最多,具有良好的界面改性效果。

Laser-induced Janus graphene/poly(p-phenylene benzobisoxazole)fabrics with intrinsic flame retardancy as flexible sensors and breathable electrodes for fire-fighting field

Conventional firefighting clothing and fire masks can protect firemen’s safety to a certain extent,whereas cannot perceive environmental hazards and monitor their physical status in real time.Herein,we fabricated two kinds of Janus graphene/poly(pphenylene benzobisoxazole)(PBO)fabrics by laser direct writing approach and evaluated their performance as intelligent firefighting clothes and fire masks.The results showed that the Janus graphene/PBO fabrics were virtually non-combustible and achieved the highest thermal protection time of 18.91 s ever reported in flame,which is due to the intrinsic flame-retardant nature of PBO fibers.The graphene/PBO woven fabrics-based sensor showed good repeatability and stability in human motion monitoring and NO_(2)gas detection.Furthermore,the piezoelectric fire mask was assembled with graphene/PBO nonwoven fabric as electrode layer and polyvinylidene fluoride(PVDF)electrostatic direct writing film as piezoelectric layer.The filtration efficiency of the fire mask reaches 95%for PM_(2.5)and 100%for PM_(3.0),indicating its effective filtration capability for smoke particles in fires.The respiratory resistance of the piezoelectric fire mask(46.8 Pa)was lower than that of commercial masks(49 Pa),showing that it has good wearing comfort.Besides,the piezoelectric fire mask can be sensitive to the speed and intensity of human breathing,which is essential for indirectly reflecting the health of the human body.Consequently,this work provides a facile approach to fabricate next-generation intrinsic flame-retardant smart textiles for smart firefighting.

聚芳硫醚砜及其制品的研究进展

通过文献归纳法总结无水硫化钠法(常压法、高压法)、含水硫化钠法(高压法、常压法)、硫磺法、硫氢化钠法、聚苯硫醚氧化法等合成聚芳硫醚砜的常用方法。含水硫化钠法可获得高分子量的聚芳硫醚砜,采用常压与高压含水硫化钠合成的聚芳硫醚砜分子量相当,其设备与工艺要求不高,生产稳定性好、周期短、成本低,该方法是一种理想的合成聚芳硫醚砜的方法。为提高聚芳硫醚砜的物理性能、化学性能,对其进行改性,通过相分离制膜法制备的聚芳硫醚砜膜可应用于染料等水体污染物的治理,通过静电纺丝法制备聚芳硫醚砜纤维膜可应用于油水分离、水体污染物治理及空气过滤净化。研究结果表明,聚芳硫醚砜高聚物及其膜制品具有重要的应用前景。

高活性聚苯硫醚树脂的制备及其性能研究

本文研究探讨了不同端基调节剂对聚苯硫醚(PPS)树脂实施端基处理后对其反应活性及熔融结晶温度(Tc2)的提升。通过对比分析,发现以含羟基芳香族硫醇化合物为端基调节剂时,PPS树脂的反应活性和Tc2提升更明显。后续洗涤纯化过程中增加酸洗步骤,可以进一步促进树脂反应活性与Tc2的提升,对于优化共混改性挤出过程中复合材料的整体性能尤为关键。

STUDIES ON THE POLYPYRROLE/POLYELECTROLYTE MOLECULAR COMPOSITES

The potyelectrolyte of propane sulfonate(PS) grafted PPTA copolymers——PPTA-PS, PPTA[O]-PS, PPTA[C]-PS were prepared and used as electrolyte in the process of electrochemical polymerization of pyrrole to form the molecular composite polypyrrole (PPY)/Polyelectrolyte.The preparation and liquid crystalline property of three kinds of polyelectrolyte, the electrical conductivity, mechanical properties, SEM and thermoproperties of PPY/polyelectrolyte are presented in detail.

RAMAN SPECTROSCOPIC STUDY ON THE CHAIN CONFORMATION OF ELECTROSYNTHESIZED POLY(ρ-PHENYLENE)FILMS

Poly（p-phenylene） （PPP） films have been electrochemically deposited on mirrorlike stainless steel （SS） electrode surfaces by direct oxidation of benzene in boron trifluoride diethyl etherate （BFEE） solutions at a constant applied potential of 1.7 V （versus Ag/AgCl）. The chain conformations of as-grown PPP films have been studied by Raman spectroscopy. The results demonstrated that high synthesis temperature favors the formation of planar PPP, and the conformation of planar PPP can be changed into torsional PPP by cooling treatment.

CONFORMATION AND CHAIN PACKING STRUCTURES OF POLY (ρ-PHENYLEN BENZOBISTHIAZOLE) BY MOLECULAR SIMULATION

The conformation, the chain packing stabilization and the unit cell modeling of poly(p-phenylene benzobisthiazole) have been investigated by using molecular simulation techniquein the present work. A coupling behaviour of σ-bond rotations at either side of the pheny-lene ring or the heterocyclic ring was found surely to exceed a length of the repeat unit ofthe polymer chain. For a single chain model, the stable torsion angle of the repeat resultedat 14°. In the crystalline cell minimization, the dihedral angle along the polymer chaincould even be stabilized in various values. It therefore indicates that the intermolecularinteraction does play a considerable role for this polymer forming the conformation. Ac-cording to cohesive energies calculated for these unit cell models, the torsion angle in themost stable crystalline cell is 0°. When the chains packing together, there exist so manyenergy stable wells along the chain axis 0.35--0.36nm apart from neighbouring chains.Most of the unit cells have quite closed cohesive energies. These factors thus cause thedifficulty of forming an unique perfect crystalline structure of the polymer. The presentstudy suggested a number of reasonable unit cells, and the most stable crystalline structurefor this polymer that is monoclinic, non-primitive unit cell.