氨酯脲型聚醚胺的合成及其增韧环氧树脂的研究

合成了不同相对分子质量的四元伯胺封端的氨酯脲型聚醚胺(TAPEU),并用于增韧双酚A型环氧树脂/二乙烯三胺(DGEBA/DETA)固化体系。利用核磁氢谱和傅里叶红外光谱(FTIR)表征了TAPEU的结构,系统表征了TAPEU改性DGEBA/DETA材料的氢键化程度、玻璃化转变温度、交联网络结构、拉伸断裂面形貌特征以及材料的力学性能。结果表明,成功合成了不同相对分子质量的TAPEU;当TAPEU相对分子质量增加时,材料交联密度降低,氢键化作用增强,玻璃化转变温度有所增加;引入TAPEU改性环氧树脂材料体系,断裂面具有明显韧性断裂特征,且出现微相分离;TAPEU改性环氧树脂材料的韧性和冲击强度有明显的提高。与未改性环氧树脂相比,添加摩尔分数为50%TAPEU2000的改性材料冲击强度提高了65%,断裂伸长率提高了330%。     

橡胶增韧环氧树脂增韧机理的断裂力学研究

测量了 ＣＴＢＮ增韧环氧树脂的ＪＲ阻力曲线，利用理想弹塑性平面应变Ｉ型定常扩展裂纹的局部解及塑性介质中孔洞演化的Ｒｉｃｅ－Ｔｒａｃｅｙ方程，近似计算了裂纹尖端附近的孔洞化塑性体膨胀和残余应变能密度。通过对增韧机制的力学分析．得到定常扩展裂纹与起裂状态时的断裂韧性差值与 ＣＴＢＮ体积分数及材料断裂应变的关系式，它对环氧基材料的增韧设计有一定的指导意义。     

复相陶瓷中颗粒桥联与相变协同增韧作用的力学分析

本文对复相陶瓷内延性金属颗粒和相变颗粒的协同增韧作用进行了力学分析，其中颗粒桥联效应还考虑了桥联颗粒与基体间工艺残余应力的影响，相变效应考虑了相变体膨胀和剪切塑性对增韧的共同贡献。数值计算结果与Ａｍａｚｉｇｏ－Ｂｕｄｉａｎｓｋｙ的结果及２Ｙ－ＴＺＰ／２０ＶＯＬ％Ｎｉ的实验结果作了比较。     

Phase Morphology and Mechanical Properties of Polyamide-6/Polyolefin Elastomer-g-Maleic Anhydride Blends

The effects of addition of varying amounts of polyolefin elastomers (POE) (with and/or without grafted maleic anhydride) on the morphology and mechanical properties of polyamide-6 (PA6)-based blends were studied. Scanning electron microscopy (SEM) was employed to obtain some detailed quantitative analyses of the morphology of the fracture behavior for the blends containing 80 wt% PA6 and 20 wt% total elastomer. Impact strength, tensile strength, and flexural strength were also measured for these blends. The results showed that POE and PA6 were an incompatible system, but the POE-g-MAH was compatible and had a toughening effect on PA6. PA6-g-POE was formed through the reaction between POE-g-MAH and PA6 during the melt extrusion process, which reduced the size of the dispersed phase and improved the impact and tensile strength of the blends. The impact strength was improved by nine times compared with the pure PA6 or the binary blend PA6/POE when the blend ratio of the ternary blend PA6/POE/POE-g-MAH was 80/16/4.     

Structure and property relationships in model diglycidyl ether of bisphenol‐a and diglycidyl ether of tetramethyl bisphenol‐a epoxy systems. I. Mechanical property characterizations

Model epoxy networks, with variations in crosslink density and in epoxy monomer rigidity, were prepared to study how the network structure affects modulus, T_g, and toughness/toughenability of epoxy resins. Diglycidyl ether of bisphenol‐A and diglycidyl ether of tetramethyl‐bisphenol‐A, along with the corresponding chain extenders, were chosen to study how monomer backbone rigidity and crosslink density affect physical and mechanical properties of epoxies. The present study indicates that, as expected, the backbone rigidity of the epoxy network, not the crosslink density alone, will strongly influence modulus and T_g of epoxy resins. Upon rubber toughening, it is found that the rigidity of the epoxy backbone and/or the nature of the crosslinking agent utilized are most critical to the toughenability of the epoxy. That is, the well‐known correlation between toughenability and the average molecular weight between crosslinks (M_c) does not necessarily hold true when the nature of epoxy backbone molecular mobility is altered. The potential significance of the present findings for a better design of toughened thermosets for structural applications is discussed. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2137–2149, 1999     

Epoxies toughened with triblock copolymers

Three different commercial triblock copolymers from Arkema were evaluated as potential toughening agents for two different lightly crosslinked epoxies. It was found that the plane strain fracture toughness, K_IC, was on the order of 3.0 MPa√m for 10 parts per hundred resin (phr) of NanoStrength™ E20 resin (a styrene–butadiene–methylacrylate, SBM, type triblock copolymer) in epoxies cured with either aminoethylpiperazine or piperidine. In contrast, 10 phr NanoStrength E40 resin (also an SBM type triblock copolymer) was ineffective in toughening such epoxies. The difference in toughening effectiveness was attributed to the smaller amount of polybutadiene present in the E40 resin. The third toughening agent from Arkema was NanoStrength M22 resin, which is a symmetric triblock copolymer consisting of side blocks of PMMA surrounding a center block of poly(butyl acrylate) and is designated as MAM. At 10 phr MAM both lightly crosslinked epoxies exhibited improvements in toughness. Morphologies were characterized using TEM and toughening mechanisms revealed using SEM and TOM. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1470–1481, 2007     

Toughening of Epoxy Nanocomposites: Nano and Hybrid Effects

In this paper, we review recent progress made in the field of epoxy-based binary and ternary nanocomposites containing three-, two-, and one-dimensional (i.e., 3D-, 2D-, and 1D) nano-size fillers with a special focus on their fracture behaviors. Despite investigations conducted so far to evaluate the crack-resistance of epoxy nanocomposites and attempts made to clarify the controlling toughening mechanisms of these materials, some questions remain unsolved. It is shown that silica nanoparticles can be as effective as rubber particles in improving the fracture toughness/energy; but incorporation of carbon nanotubes (CNTs) or clay platelets in epoxy matrices delays crack growth only modestly. The “nano” effects of silica (<25 vol.%) and rubber (>10 wt.%) nanoparticles in toughening epoxy resin are confirmed by comparison with silica and rubber micro-particles of the same loading. There is clear evidence of both synergistic and additive toughening effects in the silica/rubber/epoxy ternary nanocomposites. In addition, positive hybrid toughening effect has been observed in the nano-rubber/CNT/epoxy composites; however, a negative hybrid effect is predominant in nano-clay/nano-rubber/epoxy ternary nano-composites. Future research directions for epoxy-based nanocomposites towards multi-functional applications are discussed.     

PVC/ABS合金的研制与加工

为了拓宽硬质PVC制品的应用,克服PVC/ABS弹性体增韧的缺点.采用无机刚性粒子活性碳酸钙或有机刚性粒子PS进行增韧改性,使材料的抗冲击性能得以提高,并改善其加工性能及外观。着重探讨PVC/ABS合金的组成,力学性能和加工。     

Ce-TZP陶瓷材料中裂纹扩展路经的TEM观察

在透射电镜(TEM)下原位观察了,Ce—TZP陶瓷材料中裂纹扩展过程,发现其与一些金属中裂纹扩展过程较相似,先在主裂纹前端形核微裂纹、微裂纹长大、然后主裂纹与微裂纹连接向前扩展。在裂尖应力场的作用下,裂尖附近有部分四方相发生马氏体相变,增加了材料的断裂韧性。同时还观察到裂纹弯曲和转向。实验还发现在该材料中主裂纹尖端并不尖锐,而为钝裂纹。     

酚醛树脂泡沫塑料增韧改性的研究

研究了预聚体的用量对酚醛泡沫塑料的表观密度、抗冲击强度、压缩强度、吸水率和阻燃性等性能的影响，用SEM观察了酚醛泡沫塑料泡体的微观形貌。结果表明：当预聚体的加入量为8％时，酚醛泡沫塑料的表面密度由0．693g／cm^3下降为0．598g／cm^3；冲击强度和压缩强度分别提高了50％和96．5％；吸水率由2．08％降低到了1．38％；阻燃性有所下降。