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Structure-property relationships of bismaleimides.

机译：双马来酰亚胺的结构-性质关系。

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The purpose of this research was to control and systematically vary the network topology of bismaleimides through cure temperature and chemistry (addition of various coreactants) and subsequently attempt to determine structure-mechanical property relationships. Characterization of the bismaleimide structures by dielectric, rheological, and thermal analyses, and density measurements was subsequently correlated with mechanical properties such as modulus, yield strength, fracture energy, and stress relaxation.; The model material used in this investigation was 4,4{dollar}spprime{dollar}-bismaleimidodiphenyl methane (BMI). BMI was coreacted with either 4,4{dollar}spprime{dollar}-methylene dianiline (MDA), o,o{dollar}spprime{dollar}-diallyl bisphenol A (DABA) from Ciba Geigy, or diamino diphenyl sulfone (DDS). Three cure paths were employed: a low-temperature cure of 140{dollar}spcirc{dollar}C where chain extension should predominate, a high-temperature cure of 220{dollar}spcirc{dollar}C where both chain extension and crosslinking should occur simultaneously, and a low-temperature (140{dollar}spcirc{dollar}C) cure followed immediately by a high-temperature (220{dollar}spcirc{dollar}C) cure where the chain extension reaction or amine addition precedes BMI homopolymerization or crosslinking. Samples of cured and postcured PMR-15 were also tested to determine the effects of postcuring on the mechanical properties.; The low-temperature cure condition of BMI/MDA exhibited the highest modulus values for a given mole fraction of BMI with the modulus decreasing with decreasing concentration of BMI. The higher elastic modulus is the result of steric hindrance by unreacted BMI molecules in the glassy state. The moduli values for the high- and low/high-temperature cure conditions of BMI/MDA decreased as the amount of diamine increased. All the moduli values mimic the yield strength and density trends.; For the high-temperature cure condition, the room-temperature modulus remained constant with decreasing mole fraction of BMI for the BMI/DABA and BMI/DDS systems. Postcuring PMR-15 increases the modulus over that of the cured material even though density values of cured and postcured PMR were essentially the same.; Preliminary results of a continuous and intermittent stress relaxation experiment for BMI:MDA in a 2:1 molar ratio indicate that crosslinking is occurring when the sample is in the undeformed state.; Computer simulation of properties such as density, glass transition temperature, and modulus for the low-temperature cure conditions of BMI/MDA and BMI/DABA were completed. The computer modeling was used to help further understand and confirm the structure characterization results. The simulations correctly predicted the trends of these properties versus mole fraction BMI and were extended to other BMI/diamine systems.
机译：这项研究的目的是通过固化温度和化学作用（添加各种共反应物）来控制和系统地改变双马来酰亚胺的网络拓扑结构，并随后尝试确定结构-机械性质的关系。通过介电，流变和热分析表征双马来酰亚胺结构，然后将密度测量结果与机械性能关联，如模量，屈服强度，断裂能和应力松弛。在这项研究中使用的模型材料是4,4 {dollar} spprime {dollar}-双马来酰亚胺二苯甲烷（BMI）。 BMI与Ciba Geigy的4,4 {dol} spprime {dollar}-亚甲基二苯胺（MDA），o，o {dol} spprime {dollar}-二烯丙基双酚A（DABA）或二氨基二苯砜（DDS）共同作用。采用了三种固化途径：在140 dolspcirc {dollar} C的低温固化中，扩链应占主导地位；在220 dolspcirc {dollar} C的高温固化中，扩链和交联均应发生同时，在链增长反应或胺加成先于BMI均聚之前，先进行低温（140 {spC）的固化，然后立即进行高温（220CspC）的固化。交联。还测试了固化和后固化的PMR-15样品，以确定后固化对机械性能的影响。对于给定的BMI摩尔分数，BMI / MDA的低温固化条件表现出最高的模量值，其模量随着BMI浓度的降低而降低。较高的弹性模量是玻璃态的未反应BMI分子发生位阻的结果。 BMI / MDA的高温和低温/高温固化条件下的模量随二胺含量的增加而降低。所有模量值都模拟屈服强度和密度趋势。对于高温固化条件，对于BMI / DABA和BMI / DDS系统，随着BMI摩尔分数的降低，室温模量保持恒定。即使固化和后固化的PMR的密度值基本相同，后固化的PMR-15的模量也高于固化材料。 BMI：MDA的摩尔比为2：1的连续和间歇应力松弛实验的初步结果表明，当样品处于未变形状态时，就会发生交联。完成了BMI / MDA和BMI / DABA低温固化条件下的密度，玻璃化转变温度和模量等特性的计算机模拟。使用计算机建模来帮助进一步理解和确认结构表征结果。该模拟正确地预测了这些特性相对于摩尔分数BMI的趋势，并已扩展到其他BMI /二胺系统。

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