双马来酰亚胺树脂的增韧改性研究

综述了目前双马来酰亚胺树脂增韧改性的主要方法，并对其工艺改性提出建议。增韧改性主要通过分子结构的改变或形态控制来实现。这些方法有原位聚合法增韧改性、二元胺扩链增韧改性、高性能热塑性树脂增韧改性、烯丙基化合物增韧改性、BMI内扩链法增韧改性和液晶增韧改性等方法。并对我国双马来酰亚胺树脂改性的研究现状及其发展趋势作了探讨。     

液晶双马来酰亚胺/二胺基二苯醚齐聚物的研究

采用二胺基二苯醚（DDE）作为扩链剂,合成了含侧甲基的液晶双马来酰亚胺的齐聚物。用FT-IR、1H-NMR、TGA、DSC、HSPM研究了MBMI（液晶马来酰亚胺）与DDE的摩尔比为1：1,2：1,3：1时各种双马来酰亚胺齐聚物的结构、热性能和热致液晶行为,并用红外积分强度法对齐聚物的反应机理进行了探讨。研究表明,共聚反应是通过MBMI与DDE的双键加成反应机理进行的。与液晶双马来酰亚胺（MBMI）相比,其齐聚物的熔点降低,当MBMI与DDE的摩尔比为1：1时,齐聚物的熔点降低最多为64℃,但扩链后对齐聚物的热失重性能影响不大。热台偏光显微镜观察表明,齐聚物有较好的热致液晶特征,并且能够保留在交联网络中形成液晶聚合物网络材料。     

双马来酰亚胺和有机硅改性环氧树脂制备与表征

为改善环氧树脂耐疲劳性、耐热性和抗冲击韧性,选用有机硅和双马来酰亚胺对环氧树脂改性。试验使用有机硅对环氧树脂改性,采用4,4'-二氨基二苯甲烷(DDM)对双马来酰亚胺(BMI)进行二元胺扩链改性,再将二者复合,确定了参考配方和技术指标。     

QY8911—Ⅲ高韧性双马来酰亚胺树脂及其复合材料性能研究

2.内扩链双马来酰亚胺的合成及表征 上述结构的双马来酰亚胺国内尚无生产,也未见到有关此类双马来酰亚胺合成的研究报告。因此,我们于一九九一年着手并首先合成了两种相应的含醚键的二胺,然后再与马来酸酐反应。从而得到最终产品,具体     

双马来酰亚胺树脂扩链增韧改性研究

研究了采用腰果壳油增韧改性双马来酰亚胺树脂的方法，双马来酰树脂虽具有突出的耐热性，良好的机能及加工性能，但其最大不足是固化物脆性大，因此必须引进长链的柔性分子或分合物对双马来酰亚胺树脂加以改性，增加其韧性，改善其机械性性能，扩大其应用邻域，腰果壳油具有柔性长链分子，而且还有不饱和双键，能与双马来酰亚胺树脂的不饱和双键反应，它是一种良好的改性剂，本篇论文探讨了双马来酰亚胺树脂与腰果壳油长链分子反应机理，考察了改性树脂的力学性能和热学性能，对其工艺和配方也作了初步探讨。     

双马来酰亚胺树脂改性研究进展

综述了双马来酰亚胺增韧改性的研究进展,介绍了各种改性方法及其机理.内容包括内扩链新型BMI合成改性、胺类扩链增韧改性、烯丙基系列化合物共聚增韧改性、橡胶共混增韧改性、热塑性树脂共混增韧改性、氰酸酯树脂增韧改性等几个方面.     

含芳酰胺键的液晶双马来酰亚胺的合成与表征

通过对马来酰亚胺基苯甲酸及其酰氯化路线合成了两种含芳酰胺键的液晶双马来酰亚胺Ⅰ b和Ⅱ b;制备了二苯甲烷二胺与液晶双马来酰亚胺Ⅱ b的扩键其聚物Ⅲb。经FTIR、~1H-NMR谱对合成产物的结构进行了表征,表明1710cm~(-1)的酰亚胺羰基和1646cm~(-1)酰胺键,交联反应或扩链反应发生在双马来酰亚胺的双键上。经热分析DTA/DSC及热台偏光显微镜表征了其热性能及液晶相变特征,相变过程是一个非平衡不可逆过程。     

双马来酰亚胺树脂改性研究进展

对双马来酰亚胺树脂(BMI)增韧改性方法,包括橡胶、芳香聚酯、热塑性树脂共混法,氰酸酯共固法,二胺加成扩链法、烯丙基化合物共聚法、长链型BMI合成法等,对BMI的工艺性及自熄阻燃性等方面的改进研究进展加以综述,并对其它改性方法进行了介绍。     

QY8911—Ⅲ高韧性双马来酰亚胺树脂及其复合材料性能研究

本文介绍了Q8911-Ⅲ双马树脂的增韧途径、合成方案,并对扩链双马来酰亚胺的合成,特性和表征进行讨论。关于T300/QY8911-Ⅲ复合材料的性能,本文侧重讨论其冲击后压缩强度,并同国外同类树脂进行比较。另外,本文给出了T300/QY8911-Ⅲ复合材料的若干力学性能数据。     

扩链改性聚对苯二甲酸丁二醇酯流变性能的研究

利用毛细管流变仪和转矩流变仪对扩链改性聚对苯二甲酸丁二醇酯(PBT)的流变性能进行了研究，讨论了扩链剂用量对熔体流变性能的影响。结果表明：PBT经扩链改性后熔体的扭矩有显著的提高，在相同剪切速率下，其动态粘度比空白样增加了2～4倍，说明扩链剂对其有明显的扩链效果；其流动特性更趋于非牛顿型流体。     

Photophysical properties of fluorene‐based copolymers synthesized by connecting twisted biphenyl units with fluorene via para‐ and meta‐linkages

BACKGROUND: Wide bandgap semiconducting polymers are of great interest in the development of organic and polymeric emissive materials for display purposes since they can be used to generate light of all colors either by irradiation of luminescent dyes or by energy transfer to emissive dopants. The aim of the present work is to construct new fluorene‐based semiconducting polymers with a wide bandgap. RESULTS: A novel polyfluorene derivative, poly[(9,9‐dihexyl‐2,7‐fluorene)‐alt‐(5,7‐dihydrodibenz[c,e]oxepin)], with a wide bandgap, was synthesized by connecting rigidly twisted biphenyl monomers with dihexylfluorene via para‐linkages and it was compared with poly[(9,9‐dihexyl‐2,7‐fluorene)‐alt‐(spirocyclohexane‐1,6′‐dibenzo[d,f][1,3]dioxepin)], which has meta‐linkages. Both polymers emit in the ultraviolet and blue regions. Electronic spectral absorption data and electrochemical measurements demonstrate that ca 40° torsion angle of the biphenyl units induces an increase in the HOMO–LUMO gap of 0.18 eV, and that meta‐linkage of the twisted segment in the polymer induces another increase of 0.24 eV compared to polydihexylfluorene. CONCLUSION: The new twisted biphenyl compounds are efficient segments to tune the bandgaps of conjugated polymers. The two fluorene‐based copolymers have wide bandgaps and exhibit potential as host materials. Copyright © 2008 Society of Chemical Industry     

Influence of accelerator/sulphur and co-agent/peroxide ratios in mixed vulcanisation systems on cure characteristics,mechanical properties and heat aging resistance of vulcanised SBR

The influence of accelerator/sulphur and co-agent/peroxide ratios on cure characteristic and vulcanisate properties in mixed vulcanisation of styrene butadiene rubber (SBR) was investigated in this work. Accelerator/sulphur ratio was investigated with three alternative sulphur curing systems, namely conventional, semi-efficient and efficient vulcanisation (EV) systems. Zinc dimethacrylate (ZDMA) was used as a co-agent to enhance the performance of peroxide and to provide ionic linkages. Ionic linkages contributed by ZDMA create bridges between two polymer chains. The ZDMA/peroxide ratio was varied from 2 to 10. The concentration of dicumyl peroxide was held fixed while the ZDMA content was varied. Cure characteristics, mechanical properties, dynamic mechanical properties and heat aging resistance were investigated in relation to the crosslink structure. Increasing the ZDMA/peroxide ratio significantly increased density of ionic linkages, especially in combination with the EV system. The combination of EV system with high ZDMA/peroxide ratio provided the highest ionic crosslink density and the lowest polysulphidic crosslink density: this enhanced the mechanical properties, the dynamic mechanical properties and the thermal stability of SBR vulcanisates.     

Effect of interfacial chain structure on toughening behaviour in rubber modified poly(methyl methacrylate)

Core-shell composite particles were prepared by a heterocoagulation and annealing process, in which control of the number of chemical linkages in the interfacial zone without changing other properties was possible using five kinds of small size shell particles (SP) with different carboxyl charge density and one large size core particle (LP) with an epoxy functional group. These functional groups were capable of associating with one another through chemical reaction by thermal treatment. With increase of surface functionality of SP, the toughness was found to be higher. This indicated that a higher number of interfacial linkages between core and shell materials resulted in an increase in the critical stress intensity factor K_Ic of the modified poly(methyl methacrylate) (PMMA) composite. The interfacial properties between core and shell phase therefore play an important role in the impact behaviour of composite materials. ©1997 SCI     

Effect of incorporation of star-shaped polycaprolactone on structure-properties relationship of chitosan-based networks via urethane/urea linkage

A chitosan-based network was fabricated using hexamethylene diisocyanate as a crosslinking agent. The effect was investigated of incorporating star-shaped polycaprolactone (stPCL) into chitosan-based networks (CS/stPCL), where the stPCL content varied from 10 to 50 wt%. Quantitative analyses of the urethane/urea linkages and of the stPCL content in the networks were determined based on curve fitting and Soxhlet extraction, respectively. The optimum weight ratio was 80:20 for CS and stPCL (80CS20stPCL), with the highest urethane/urea linkages and stPCL content in the network (30.73%). The compressive testing and rheological analysis indicated that incorporating stPCL enhanced the compressive strength and rheological properties of the chitosan-based network. In addition, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay of the CS/stPCL network had a cell viability percentage greater than 70%. The CS/stPCL network promoted the formation of an apatite layer on the surface, indicating that the CS/stPCL network could be a promising candidate for tissue engineering.     

Postsynthetic Covalent Modification in Covalent Organic Frameworks

The modification of covalent organic frameworks (COFs) based on postsynthetic covalent linkages is discussed in this review. In this strategy, the COF is preparedas scaffold and then assembled with functional groups with preservation of structural skeleton. Recent studies indicate that a number of COFs, such as COF-5 and 3D-OH-COOF, are controllable to postsynthetic modification. Furthermore, covalentmodifications including triazole, ester, amide, sulfide, o-carbamate, ether, and oxime are suitable for postsynthetic functionalization. The rapid development of postsynthetic modification demonstrates that this approach will provide a general platform to create COFs as robust functional porous materials for wide applications.     

含芳醚芴二胺/环氧树脂固化反应动力学及性能研究

以9,9-双[4-4-氨基苯氧基苯基]芴(BAOFL)作为固化剂,采用非等温DSC技术,研究了BAOFL/环氧树脂(E-51、TDE-85和芴基环氧树脂)体系的固化反应动力学,利用动态热机械分析仪(DMA)和热重分析仪(TGA)测试了固化树脂的力学性能和热稳定性。结果表明,固化反应活化能与环氧树脂和固化剂的结构密切相关,芳醚的引入提高了氨基与环氧基的反应性,固化树脂呈现出优良的热性能和力学性能,其玻璃化转变温度(T)达到206~248℃,贮能模量为2.54~2.94 GPa,初始热分解温度312~375℃,700℃g时的残炭率达到15.2%~31.7%。()     

Potential visible WO3/GO composite photocatalyst

Graphene oxide (GO) was synthesized by Hummers method. GO and tungsten oxide (WO₃) composites were successfully prepared by deposition of WO₃ on GO surface to make efficient visible light catalyst. Scanning electron microscopy of pure GO revealed that GO films are folded with kinked and wrinkled edges. The interspaces layers are partially filled by WO₃ nanoparticles with their less wrinkled edges and smooth surface of composite. Moreover, composite sheets are thin and transparent which allow easy penetration of light. EDS showed the presence of C, O, and W in GO/WO₃ composites with no impurity. UV-Vis diffused reflectance spectra showed red shift with the increase in WO₃ contents. Raman spectra of GO and GO/WO₃ composite show G and D bands. These bands reduced in intensity in composite sample due to removal of oxygenated functional groups with some new peaks of WO₃. FT-IR confirmed successful oxidation of graphite into GO with reduction in GO because oxide-related bond groups decrease after reduction. The transmittance peaks of WO₃ in composite sample are appeared indicating W-O-C linkages. The highest visible light activity of the composite is due to easy penetration of light with deposition of WO₃, low band gap, and new linkages.     

H n.m.r. study on the sequence length of polysulphide linkages in the copolymer of chloroprene and sulphur

The sulphur rank distribution and the structures of chloroprene units in the chloroprene-sulphur copolymer have been investigated in detail by proton nuclear magnetic resonance spectroscopy (¹H n.m.r.). Two factors, the sulphur rank and the structures of chloroprene units, which complicate the spectrum, were elucidated by modification of the copolymer structure through partial and full reductions of the polysulphide linkages. The populations of the chloroprene units with different structures adjacent to the sulphur units were found to be different from those of the homosequence. It was found that the major sulphur unit in the copolymer is octasulphide, the next disulphide and the least common are the other polysulphides composed of 3–7 sulphur atoms. No evidence of monosulphide was found.     

Synthesis and characterization of polyetherimides containing multiple ether linkages and pendent pentadecyl chains

4‐(4‐(4‐(4‐Aminophenoxy)‐2‐pentadecylphenoxy)phenoxy)aniline (APPPA) was synthesized starting from cashew nut shell liquid‐derived bisphenol, i.e. 4‐(4‐hydroxyphenoxy)‐3‐pentadecylphenol, by nucleophilic substitution reaction with 4‐chloronitrobenzene followed by reduction of the formed 4‐(4‐nitrophenoxy)‐1‐(4‐(4‐nitrophenoxy)phenoxy)‐2‐pentadecylbenzene. Three new polyetherimides containing multiple ether linkages and pendent pentadecyl chains were synthesized by one‐step high‐temperature solution polycondensation of APPPA in m‐cresol with three aromatic dianhydrides, i.e. 3,3′,4,4′‐oxydiphthalic anhydride, 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride and 3,3′,4,4′‐biphenyltetracarboxylic dianhydride. Inherent viscosities and number‐average molecular weights of the polyetherimides were in the ranges 0.66–0.70 dL g^?1 and 17 100–29 700 g mol^?1 (gel permeation chromatography, polystyrene standards), respectively, indicating the formation of reasonably high molecular weight polymers. The polyetherimides were soluble in organic solvents such as chloroform, dichloromethane, tetrahydrofuran, pyridine, m‐cresol, N,N‐dimethylformamide, N,N‐dimethylacetamide, N‐methylpyrrolidone and dimethylsulfoxide, and could be cast into transparent, flexible and tough films from their solutions in chloroform. The polyetherimides exhibited glass transition temperatures (T_g) in the range 113–131 °C. The lowering of T_g could be attributed to the combined influence of flexibilizing ether linkages and pentadecyl chains which act as ‘packing‐disruptive’ groups. The temperature at 10% weight loss (T₁₀), determined from thermogravimetric analysis in nitrogen atmosphere, was in the range 460–470 °C demonstrating good thermal stability. The virtues of solubility and large gap between T_g and T₁₀ mean that the polyetherimides containing pendent pentadecyl chains have possibilities for both solution as well as melt processability. © 2015 Society of Chemical Industry