Copolymer networks from carboxyl‐containing polyaryletherketone and diglycidyl ether of bisphenol‐A: Preparation and properties

This article presents a new type of epoxy‐toughening system, in which high‐T_g polyaryletherketone (PEK‐L) containing one carboxyl group per repeating unit was utilized to randomly copolymerize with epoxy resin (DGEBA) to form crosslinking network. Compared to the neat epoxy resin, the PEK‐L/DGEBA copolymers showed simultaneous enhancement in flexural strains at break by 282%, G_IC value by 193%, and flexural strength by 14%. The reason was attributed to the uniform three‐dimensional copolymer network interweaved by PEK‐L and DGEBA segments through strong covalent bonds. The copolymerization process were monitored and examined by FTIR spectra. The effect of copolymer composition on the thermal and mechanical properties as well as toughening mechanism were also investigated and discussed in detail. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010     

天然橡胶对聚乳酸的改性研究

为了更好地将聚乳酸(PLA)这种可以完全降解的环境友好型高分子材料应用在环保塑料这个领域中，并克服其固有的脆性.选用具有良好的韧性、生物相容性以及低成本可再生的天然橡胶(NR)来对PLA进行改性.采用动态硫化熔融加工的方法制备不同NR质量分数(5%～15%)的NR-PLA复合材料.通过机械性能测试发现，加入10%NR后，断裂伸长率由7.3%(PLA)升高到41.1%，表明NR对PLA具有显著增韧的效果；并且通过SEM发现两者之间相容性较好.本研究对进一步更好地应用PLA具有推进作用.     

页岩气水平井油井水泥的原位增韧技术研究

针对页岩气水平井开发过程中油井水泥作为一种非均质多孔脆性复合材料，难以承受大型水力压裂带来的非均质载荷，导致水泥环的力学完整性失效破坏问题，开展了油井水泥原位增韧技术研究。研究中采用了固相烧结法和球形重淬技术，获得了微晶铁铝酸钙（MB）作为原位增韧材料。研究结果表明，制备的原位增韧材料在提升力学性能的基础上降低了水泥石的弹性模量，养护7 d后的抗压强度可达24 MPa，抗拉强度提升50%，弹性模量降至5.55 GPa。微晶铁铝酸钙的增韧机制为：“裂纹偏转”、“裂纹终止”、“消耗断裂能”。该研究的开展对满足以页岩气开采条件下的油井水泥服役要求，延长页岩气井寿命，增加页岩气产能具有重要意义。     

Novel toughened cyanate ester resin with good dielectric properties and thermal stability by copolymerizing with hyperbranched polysiloxane and epoxy resin

A novel toughened cyanate ester (CE) resin with good dielectric properties and thermal stability was developed by copolymerizing 2,2′‐bis(4‐cyanatophenyl)iso‐propylidene (BCE) with a combined modifier (HBPSiEP) made up of hyperbranched polysiloxane (HBPSi) and epoxy (EP) resin. HBPSi was synthesized through the hydrolysis of 3‐(trimethoxysilyl)propyl methacrylate. The effect of differing stoichiometries of HBPSiEP on the curing characteristics and performance of BCE resin is discussed. Results show that the incorporation of HBPSiEP can not only effectively promote the curing reaction of BCE, but can also significantly improve the toughness of the cured BCE resin. In addition, the toughening effect of HBPSiEP is greater than single EP resin. For example, the impact strength of modified BCE resin with 30 wt% of HBPSiEP is 23.3 KJ/m², which is more than 2.5 times of that of pure BCE resin, while the maximum impact strength of EP/BCE resin is about 2 times of pure BCE resin. It is worthy to note that HBPSiEP/BCE resins also exhibit improved thermal stability, dielectric properties, and flame retardancy, suggesting that the novel toughened CE resins have great potentiality to be used as a matrix for advanced functional composites or electronic packing resins. Copyright © 2009 John Wiley & Sons, Ltd.     

Fatigue Crack Propagation Behavior of Rubber-toughened Epoxy Resin

ＩｎｔｒｏｄｕｃｔｉｏｎＡｓｅｘｃｅｌｌｅｎｔｐｏｌｙｍｅｒｉｃｍａｔｅｒｉａｌｓ,ｅｐｏｘｉｅｓａｒｅｗｉｄｅｌｙｕｓｅｄｉｎｍａｎｙｅｎｇｉｎｅｅｒｉｎｇｆｉｅｌｄｓａｓａｄｈｅｓｉｖｅｓ,ｍａｔｒｉｘｍａｔｅｒｉａｌｓｉｎｆｉｂｅｒｒｅｉｎｆｏｒｃｅｄｃｏｍｐｏｓｉｔｅｓ,ｐｏｔｔｉｎｇａｎｄｅｎｃａｐｓｕｌａｔｉｎｇ[1].Ｂｕｔｅｐｏｘｉｅｓａｒｅｕｓｕａｌｌｙｂｒｉｔｔｌｅａｎｄｅａｓｉｌｙｃｒａｃｋｅｄ[2].Ｒｕｂｂｅｒｍｏｄｉｆｉｃａｔｉｏｎ,ｔｈｅａｄｄｉｔｉｏｎｏｆａｒｕｂｂｅｒｙｐａ…     

陶瓷材料相变增韧尺寸效应的力学分析

利用计及相剪切效应的陶瓷材料本构关系和裂尖场的双参数表达式对平面应变Ⅰ型裂纹定常扩展过程进行渐近分布。基于渐近场和能量积分，得到韧性增值的估算公式，并且根据数值结果和实验现象进一步讨论相变剪切塑性和应力非奇异顶的影响。     

Al2O3基纳米复相陶瓷的研究进展

从纳米复相陶瓷的研究，发展及增韧增强的机理出发，论述了Al2O3基纳米复相陶瓷的研究进展，同时阐述了有关的增韧机理，并提出了纳米金属间化合物增韧Al2O3陶瓷的良好前景。     

Preparation and Mechanical Properties of Composites Based on Rigid Polyvinyl Chloride Filled with Organic Modified Illite Powder

Illite powder, modified by an aluminate coupling agent, was used as a filler to strengthen polyvinyl chloride (PVC) resin with mechanical properties of rigid PVC/modified illite composite being tested. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were applied for the structural characterization of the raw materials. SEM and Fourier transform infrared spectroscopy (FTIR) measurements were used for demonstrating the effect of modification of the illite powder. Results from tests of mechanical properties showed that, when the dosage of modified illite powder was 2 parts per hundred parts by weight, there was an obvious toughening effect on rigid PVC material; the notched impact strength was increased by 59% in comparison to neat rigid PVC, but the elongation of the composites decreased slightly.     

Flame retardant and toughening behaviors of bio‐based DOPO‐containing curing agent in epoxy thermoset

Based on bio‐based furfural, a phosphorus‐containing curing agent (FPD) was successfully synthesized, via the addition reaction between 9,10‐dihydro‐9‐oxa‐10 phosphaphenanthrene‐10‐oxide (DOPO) and furfural‐derived Schiff base. Then, as co‐curing agent, FPD was used to prepare flame retardant epoxy thermosets (EP) cured by 4, 4′‐diaminodiphenyl methane. The incorporated FPD improved the flame retardancy and toughness of epoxy thermoset, simultaneously. When 5 wt% FPD was added into EP, the FPD/EP achieved 35.7% limited oxygen index (LOI) value and passed UL94 V‐0 rating, meanwhile. In FPD/EP thermoset, the incorporated FPD reduced the thermal decomposition rate, increased the charring capacity, and inhibited the combustion intensity of epoxy thermoset. Through gas‐phase and condensed‐phase actions in weakening fuel supply, suppressing volatile combustion, and enhancing charring barrier effect, FPD decreased the heat release of burning epoxy thermoset, significantly. For the outstanding effectiveness on both flame retardancy and toughness, the study on FPD provides a promising way to manufacture high‐performance epoxy thermoset.     

改性聚丙烯裁切板专用料的研制

为了改进聚丙烯(PP)的低温韧性,本研究采用弹性体对PP进行了共混改性,考察了共混体系各组分含量的变化对共混物硬度、冲击强度和拉伸强度的影响,确定出制得裁切板专用料的最佳配方.研究结果表明:当wPP∶w共聚PP∶w弹性体∶wPE为某一适当比时,制得的共混料完全可以满足裁切板性能的要求.