MDI和HMDI聚氨酯脲模型化合物的红外光谱研究

以二苯基甲烷-4，4′-二异氰酸酯（MDI）、二环己基甲烷二异氰酸酯（HMDI）和扩链剂乙二胺（EDA）和2，4-二氨基-3，5-二甲硫基氯苯（DDSCB，商品名TX-2）以及聚醚二元醇PTMG为原料，采用溶液法分别合成出了4种聚醚型聚氨酯脲（PUU）模型化合物，研究了其红外谱图，并对模型化合物的红外谱图进行比较。研究结果说明MDI型PUU的NH戍氢键的状态要强于HMDI型BUU，而MDI型多嵌段PUU模型化合物的羰基戍氢键的情况刚好相反，MDI型PUU的羰基与NH戍氢键状态和HMDI型PUU相比要较弱：而且酰胺Ⅲ与NH/C=O氢键有更大的关系，而酰胺Ⅱ带与醚氧／NH氢键有更大的关系；当氢键的受体只有羰基和醚氧基时，NH更易于和醚氧形成氢键。     

邻接交联型聚氨酯脲弹性体的制备与耐温性能

以丁腈羟和聚醚多元醇、甲苯二异氰酸酯、扩链剂为原料,加入化学交联剂双二五(B25)和助交联剂N,N-马来酰亚胺间苯撑(HAV-2)制备出邻接交联型聚氨酯脲弹性体(PUU)。软化点测试说明经过B25和HAV-2在高温下的化学反应,PUU不再有软化点出现,由热塑性转变为热固性。力学性能测试表明,经过B25和HAV-2的化学交联,PUU弹性体的力学性能降低,热稳定性能明显提高。高温力学性能测试表明,交联PUU的力学性能和断裂伸长率随着温度的升高有不同程度的下降,高温力学性能保留率随B25的增加而升高。高温回弹测试表明交联PUU的硬度随温度的升高逐渐降低,而回弹性逐渐升高。     

FTIR研究催化剂对半预聚物法PUU弹性体固化过程的氢键化作用及力学性能的影响

采用原位FTIR技术跟踪了半预聚物法聚醚型聚氨酯脲的固化过程,研究了催化剂对固化过程的氢键化作用及力学性能的影响。原位FTIR的光谱数据表明,随着催化剂浓度的增加,软段形成的速率逐渐增加,氢键化脲键羰基的有序性降低,微相混合度增加。催化剂决定着弹性体的微结构和力学性能,实验结果显示：当催化剂的质量浓度为2．5‰时,聚氨酯脲PUU弹性体表现出最大的拉伸强度和撕裂强度。     

酰亚胺邻接交联型聚氨酯弹性体的制备与性能

以聚醚（PTHF）、端羟基聚丁二烯-丙烯腈（HTBN）甲苯二异氰酸酯为材料,交联剂双二五（B25）和助交联剂N,N-马来酰亚胺间本撑（HAV-2）为添加剂制备出酰亚胺邻接交联型丁腈基聚氨酯弹性体,并研究了其耐热性能。结果表明,邻接交联网络的生成,聚氨酯弹性体的力学性能降低,永久变形下降,耐温性明显提高。随着高温的升高,聚氨酯弹性体的力学性能、硬度和断裂伸长率均表现下降趋势,然而回弹性逐渐升高。     

聚氨酯弹性体的高弹模量对温度的依赖性

通过动态力学分析研究了不同交联程度的聚氨酯弹性体的高弹模量对温度的依赖性。详细分析了弹性体内部的物理交联密度随温度的变化,认为物理交联密度的下降主要是氢键的解离造成的。计算得到了试样的氢键活化能和物理交联对弹性模量的贡献,同时研究了它们随温度的变化情况。交联程度小的,氢键活化能高,氢键随温度升高的解离速率快,交联程度大的则相反。     

加热温度和冷却速度对35VS非调质易切钢组织和性能的影响

本文对各种加热温度及冷却速度下的由第一汽车厂和大连钢厂联合开发,研制的35VS非调质易切钢的组织和性能进行了研究,结果完明,珠光体体积百分数和冷却速度有关,但奥氏体晶粒尺寸随着加热温度升高而增加,并在1050℃时发生突然长大,珠光体片层间距随冷却速度的增加而减少,铁素体的显微硬度明显高于35钢中铁素体的硬度。室温强度指标σb6和σ0:2随加热温度的升高而增加,室温塑性指标和δ随加热温度升高而降低,在性能和冷却速度关系曲线中,当冷却速度为60℃/min时,35VS钢具有较好的塑性,这种冷却速度下得到的组织呈魏氏组织。     

掺杂浓度对多晶硅纳米薄膜应变系数及其线性度的影响

利用低压化学气相沉积（LPCVD）技术制备了不同掺杂浓度的多晶硅纳米薄膜,并对样品的压阻特性进行了测试．采用最小二乘法对实验数据进行拟合,得到了应变系数及其线性度与掺杂浓度的关系．实验结果表明：掺杂浓度从8．1×10^18cm^-3变化至7．1×10^20cm^-3,多晶硅纳米薄膜的纵向和横向应变系数先增加再减小,最后基本不再随掺杂浓度而变化,且纵向应变系数大于横向应变系数：掺杂浓度低于4.1×10^19cm^-3时,应变系数的非线性较大,且随掺杂浓度的升高而迅速减小;掺杂浓度高于4．1×10^19cm^-3时,应变系数的非线性较小并出现波动现象,同时纵向应变系数的非线性小于横向应变系数的非线性．利用隧道压阻理论对实验结果进行了分析．结合以前的研究结果可知,适合传感器制作的多晶硅纳米薄膜的优化掺杂浓度应为（2．0～4．1）×10^20cm^-3,为进一步利用多晶硅纳米薄膜制作传感器提供了非常有价值的参考信息．     

添加剂及其含量对交联聚乙烯高压电缆绝缘材料性能影响

为优化高压电缆交联聚乙烯（XLPE）绝缘材料配方，采用凝胶萃取、热延伸、转矩流变仪和失重法研究材料交联特性，采用红外光谱表征XLPE热氧老化特性，并测试了XLPE的力学性能和电学性能。结果表明，随交联剂过氧化二异丙苯（DCP）含量增大，XLPE凝胶含量及交联速率增大、力学性能变化较小、交流击穿强度的温度敏感性降低。优先考虑交联特性，确定DCP含量为1.8 phr。随抗氧剂含量增加，XLPE交联度降低、热延伸率稍有提高。相比单独使用0.3 phr抗氧剂300的XLPE，抗氧剂1010和1035各以0.15 phr复配使用可发生协同作用，从而更显著地抑制XLPE中羰基的形成和热氧老化，还可以在不降低交联度的前提下，改善XLPE抗焦烧性，避免预交联对XLPE性能的影响，且该材料具有更优的击穿强度温度特性和更低的介电损耗。     

水合聚氨酯脲的力学性能、组成及氢键结构变化的研究

研究了在聚氨酯脲盐溶液中（0．9％（质量）NaCl,37℃）浸泡不同时间后的静态和动态力学性能,组成,氢键结构的变化规律。结果表明,盐溶液浸泡可使平均分子量和相分离程度大大增加,并可提高力学强度和减少柔顺性,而平均分子量的增加是由于发生了分子间或分子内扩链或交联以及PTMO低聚物的逸出,FT－IR分析表明水分子不会显著改变聚氨酯脲氢链结构。     

聚四氢呋喃醚二醇/聚氧化丙烯二醇共混聚醚聚氨酯弹性体的氢键作用

分别以聚四氢呋喃醚二醇(PTMG)、聚氧化丙烯二醇(PPG)及两者共混物PTMG/PPG作为软段,以2,4-甲苯二异氰酸酯(TDI-100)和扩链剂3,3'-二氯-4,4'-二氨基二苯甲烷(MOCA)作为硬段,采用预聚体法,制备了5种PTMG/PPG不同配比的浇注型聚氨酯弹性体。通过红外分析、差示扫描量热分析、动态力学热分析着重研究了PTMG/PPG不同配比对聚氨酯弹性体氢键的影响。结果表明,随着PPG型预聚体在混合预聚体中的含量增加,聚氨酯中羰基区总氢键度及脲羰基氢键度变化不大,氨酯羰基氢键度呈现先增加后减小的趋势;氨酯羰基氢键解离活化能变大,氢键趋于完善;硬段相长程有序结构熔融焓减小,脲羰基氢键完善程度下降。     

Investigation of kinetics and morphology development for polyurethane-urea extended by DMTDA

The relationship between the reactions kinetics and morphology development during the polyurethane-urea (PUU) curing process has been investigated simultaneously by in situ Fourier transform infrared spectroscopy (FTIR). The data of the FTIR spectra showed that with the increase of conversion, the absorbance of NH bands increases and its band sites shifts to lower wavenumbers; the absorbance of free urethane carbonyl kept nearly constant at low conversion, and then decreased much because of the interaction of the formed urea links, and then changed little at high conversion owing to the diffuse control. The band sites of hydrogen bonded urea carbonyl similarly shifted to lower wavenumbers and the absorbance of the hydrogen bonded urea carbonyl, associated with the phase separation of hard segments, became stronger with buildup of hydrogen bond between urea links. The carbonyl bands available during curing process were further assigned. Both interactions, such as hydrogenised effect and phase separation, played a major role in the matrix formation of the PUU polymer.     

Investigation of kinetics and morphology development for polyurethane-urea extended by DMTDA

The relationship between the reactions kinetics and morphology development during the polyurethaneurea (PUU) curing process has been investigated simultaneously by in situ Fourier transform infrared spectroscopy (FTIR). The data of the FTIR spectra showed that with the increase of conversion, the absorbance of NH bands increases and its band sites shifts to lower wavenumbers; the absorbance of free urethane carbonyl kept nearly constant at low conversion, and then decreased much because of the interaction of the formed urea links, and then changed little at high conversion owing to the diffuse control. The band sites of hydrogen bonded urea carbonyl similarly shifted to lower wavenumbers and the absorbance of the hydrogen bonded urea carbonyl, associated with the phase separation of hard segments, became stronger with buildup of hydrogen bond between urea links. The carbonyl bands available during curing process were further assigned. Both interactions, such as hydrogenised effect and phase separation, played a major role in the matrix formation of the PUU polymer.     

Preparation and properties of adjacency crosslinked polyurethane---urea elastomers

Adjacency crosslinked polyurethane--urea (PUU) elastomers with different crosslinking density were prepared by using hydroxyl-terminated liquid butadiene-nitrile (HTBN), toluene diisocyanate (TDI) and chain extender 3,5-dimethyl thio-toluene diamine (DMTDA) as raw materials, dicumyl peroxide (DCP) as initiator, and N,N'-m-phenylene dimaleimide (HVA-2) as the crosslinking agent. The influences of the crosslinking density and temperature on the structure and properties of such elastomers were investigated. The crosslinking density of PUU elastomer was tested by the NMR method. It is found that when the content of HVA-2 is 1.5%, the mechanical properties of polyurethane elastomer achieve optimal performance. By testing thermal performance of PUU, compared with linear PUU, the thermal stability of the elastomers has a marked improvement. With the addition of HVA-2, the loss factor tanδ decreases. FT-IR spectral studies of PUU elastomer at various temperatures were performed. From this study, heat-resistance polyurethane could be prepared, and the properties of PUU at high temperature could be improved obviously.     

Crosslink density and fracture toughness of epoxy resins

A series of networks of diverse crosslink density were prepared using bifunctional epoxide prepolymers of different molecular weight, crosslinked with diamine diphenyl sulphone, and their fracture behaviour investigated. The same set of resins was also modified with a reactive rubber. The fracture toughness regularly decreased on increasing the crosslink density for all formulations. The addition of the rubber gave rise to a marked increase in toughness, though it magnified the influence of the molecular weight of the prepolymer. Tests performed with blunt notches showed that the fracture toughness was maximum at medium crosslink densities. A dispersion of rubber particles caused a toughness increase through the formation of microcavities ahead of the crack tip. Failure was preceded by a rapid volume increase caused by void coalescence.     

硬段微区结构与聚氨酯脲弹性体力学性能及耐热性的相关性

以聚四氢呋喃醚二醇(PTMG)为软段,甲苯二异氰酸酯(TDI)、二苯基甲烷二异氰酸酯(MDI)、混合异氰酸酯(n(TDI)∶n(MDI)=1∶1)分别为硬段,采用预聚体法合成了一系列不同硬段微区结构的聚氨酯脲弹性体,并通过红外光谱、热重分析、差示扫描量热以及力学表征等方法,研究了不同硬段微区结构与聚氨酯脲(PUU)体系内部微相分离、热稳定性及力学性能的相关性。结果表明,TDI型聚氨酯脲的NH官能团伸缩振动谱带出现在较低位置(3270cm~(-1)),MDI型NH官能团伸缩振动谱带出现在相对较高的位置(3285cm~(-1)),前者的T_g(-57.6℃)低于后者T_g(-49.5℃),而初始降解温度前者(294℃)高于后者(268℃),混合型的均位于两者之间。因此,TDI型PUU表现出较高的微相分离程度和硬段微区有序度,而MDI型微相混合程度较高、且微相混合程度有助于力学性能的改善。随着温度的升高,PUU内部氢键化NH官能团伸缩振动吸收强度逐渐减弱,谱带吸收位置由低波数向高波数移动,力学性能逐渐下降,当温度处于70℃左右时,其波数出现轻微的突越,力学性能也表现出较快的下降趋势。     

碳纤维/羰基铁粉复合涂层吸波效果及机理分析

在碳纤维表面化学镀镍,再将其与羰基铁粉混合制备成吸波涂层,对其吸波性能进行了测试.结果表明:在2～18 GHz内,碳纤维/羰基铁粉吸波涂层,最大吸收峰在5.92 GHz,此时反射率为-8.89 dB,反射率小于-5.00 dB的频宽为9.50 GHz;单层羰基铁粉涂层在相同厚度下,最大吸收峰为7.94 GHz,对应的反射率为-10.36 dB,反射率小于-5.00 dB的频宽为6.90 GHz;碳纤维与羰基铁粉混合后,涂层反射率小于-5.00 dB的频宽增大,有利于吸收雷达波.最后,对碳纤维/羰基铁粉吸波涂层的吸波机理进行了初步分析.     

Degradation Characterization of Ethylene-Propylene-Diene Monomer (EPDM) Rubber in Artificial Weathering Environment

Ethylene-propylene-diene monomer containing 5-ethylidene-2-norbornene as diene was exposed to artificial weathering environment produced by a xenon lamp light exposure and weathering equipment for different periods of time. The changes of surface color and mechanical properties were monitored by spectrophotometer, computer-controlled tensile testing and hardness measurements. Crosslink density of ethylene-propylene-diene monomer specimens was measured by the solvent swell method. The results showed that the surface of ethylene-propylene-diene monomer became yellower due to the form of carbonyl group. The degradation process proceeded predominantly via cross-linking. With increase in crosslink density, the tensile strength increased and the elongation at fracture decreased.     

TPU弹性体中化学交联对其形态影响的动态力学分析

研究了分别以微量的三羟甲基丙烷(TMP)和端异氰酸酯基的预聚体为交联剂的微化学交联TPU的动态力学性能的变化,分析了微量化学交联的TPU中化学交联对其形态结构的影响。结果表明,当以TMP为交联剂时,交联程度的增加会导致TPU软、硬微区相容性的增强,从而使其Tg和力学损耗值都上升;而当以端异氰酸酯基预聚体为交联剂时,交联程度的增加仅仅只会加强TPU软、硬微区间的相互联系作用,因而其Tg和力学损耗值变化不显著。