【作者】 熊需海；

【导师】 陈平；

【作者基本信息】 大连理工大学 ， 高分子材料， 2012， 博士

【摘要】 双马来酰亚胺树脂(BMI)是一类高性能热固性树脂,具有良好的加工性能、耐热性能、介电性能和机械性能。但是普通的双马来酰亚胺溶解性差、熔点高以及固化物交联密度高、性脆等缺点严重影响其在高技术领域的应用。为了克服上述缺点,本论文采用分子设计的方法在BMI分子结构中引入酚酞骨架和柔性连接链,以期在不损失耐热性能的前提下改善树脂的加工性能和固化物的冲击韧性。本论文设计、合成了三种含酞侧基链延长型双马来酰亚胺单体,并筛选出性能优异的新型单体分别与o,o’-二烯丙基双酚A(DABPA)、二苯甲烷型双马来酰亚胺(MBMI)、环氧树脂(E-51)等进行共聚改性,以期制备出综合性能优良的树脂体系。首先以酚酞、邻甲酚酞、百里酚酞为起始原料经过四步反应合成了含酚酞结构链延长型BMI (PPBMI)、含邻甲酚酞结构链延长型BMI (MPBMI)、含百里酚酞结构链延长型BMI (IPBMI)等三种新型BMI单体；采用FTIR、NMR、元素分析等手段对中间体及目标化合物的化学结构进行了表征和分析；溶解性测试表明三种单体具有良好的溶解性能；采用DSC研究了单体的固化行为,结果显示三种单体都具有较宽的熔融加工窗口,并且甲基取代基的存在不影响BMI的固化行为而异丙基取代基的存在则显著降低BMI双键的反应活性；用DMA和TGA研究了三种BMI固化物的热性能,研究表明随烷基取代基体积的增加固化物的耐热性和热稳定性降低；固化物的吸水率测试表明单体的结构对固化物的吸湿行为有显著的影响。在上述性能研究的同时探讨了BMI结构与性能间的关系。将PPBMI与DABPA预聚,制备了PPBMI/DABPA共聚树脂体系。用DSC研究了共聚体系的固化动力学并确定了固化工艺；FTIR研究了树脂体系在200℃以下的固化机理。采用DMA、TGA、力学性能以及吸水率测试研究PPBMI与DABPA摩尔配比的改变对固化物性能的影响。研究表明,随PPBMI摩尔含量的增加,固化物的储能模量、玻璃化转变温度、热稳定性和高温残碳率均有相应的提高,固化物的吸水速率和平衡吸水量则随之降低。将PPBMI加入到MBMI/DABPA中制备了PPBMI/MBMI/DABPA共聚体系。在设定马来酰亚胺基团和烯丙基基团的摩尔配比为0.87的条件下,研究了PPBMI与MBMI摩尔配比对树脂体系各种性能的影响。研究表明,随PPBMI摩尔含量的增加,改性体系固化物的橡胶态储能模量和玻璃化转变温度逐渐减低；而热稳定性和抗吸湿性能则有一定程度的提高；弯曲强度和冲击强度先小幅上升而后逐步下降,弯曲模量则是逐步提高。断裂形貌显示高PPBMI含量体系的固化物中存在气泡等缺陷。用PPBMI、E-51、4,4’-二氨基二苯砜(DDS)制备PPBMI/DDS/E-51共固化树脂体系,根据树脂体系主体的不同又细分为E-51改性PPBMI/DDS体系和PPBMI改性E-51/DDS体系。采用DSC和FTIR分析了树脂体系的固化机理,研究表明E-51改性PPBMI/DDS体系的固化机理随体系组成的改变而不同；PPBMI改性E-51/DDS体系固化过程中主要发生了环氧的固化反应和PPBMI双键与DDS的加成反应。用DMA、TGA、力学性能和吸水率测试等方法研究两类改性树脂体系固化物的各种性能。结果表明,E.51改性PPBMI/DDS体系的耐热性、热稳定性和抗吸湿性能随着E-51含量增加而降低,但是冲击强度有显著改善。PPBMI改性E-51/DDS体系的耐热性随PPBMI含量增加而降低,但是热稳定性、弯曲强度和模量、抗吸湿性能有所提高；另外,冲击强度先升高后降低,其中5%PPBMI改性体系的冲击强度最大。更多还原

【Abstract】 Bismaleimides, one of the most promising classes of high performance thermosetting resins, are known for their excellent processability and balance of thermal, electrical and mechanical properties. Howerver, the common BMI monomers are of high melting temperature and poor solubility in common organic solvents, and the cured resins have high inherent brittleness due to their high crosslink density and rigid molecular networks. These shortcomings restrict their application in high-tech fields. In order to overcome them, the molecular design "methodology was used to introduce phthalide group and flexible ether linkages into bismaleimide structure with the aim of improving the processability and enhancing the fracture toughness of the corresponding cured without sacrificing thermostability and mechanical properties.A series of chain-extended bismaleimides containing phthalide cardo structure was designed and synthesized in this paper. One monomer with high properties was selected and blended with other thermosetting resins, such as2,2’-diallyl bisphenol A (DABPA), N,N’-(4,4’-diphenylmethane)bismaleimide (MBMI), epoxy (E-51), in order to obtain preferable resin with excellent balance of properties. The main research works in this thesis are as follows.Firstly, three novel phthalide-containing bismaleimide monomers, i.e.,3,3-bis[4-(4-male-imidophenoxy)phenyl]phthalide (PPBMI),3,3-bis[4-(4-maleimido phenoxy)-3-methylphenyl]-phthalide (MPBMI),3,3-bis[5-isopropyl-4-(4-maleimidophenoxy)-2-methylphenyl]phthalide (IPBMI), were synthesized based on phenolphthalein, o-cresolphthalein and thymolphthalein, respectively. The chemical structures of the monomers were confirmed by1H and13C nuclear magnetic resonance spectroscopy (NMR) and Fourier transform infrared spectroscopy (FTIR). These monomers exhibit good solubility in common organic solvents, enabling an easy solution processing. Thermal curing behavior of these monomers was investigated by differential scanning calorimetry (DSC), displaying broad exothermic peaks and large thermal processing windows. Thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) were used to characterize the thermal stability and thermal mechanical properties of the cured BMI resins and the results exhibit the heat resistance and thermal stability were decreased along with growing bulk of the alkyl substituent. The water absorption tests of the cured products demonstrate the chemical structure exerted materially effect on moisture resistance. Based on the study of aforementioned properties, the relationships between structure and properties were discussed simultaneously.The copolymerization systems of PPBMI/DABPA were prepared, and their cure kinetics and cure cycle were analyzed by DSC. The FTIR was employed to investigate the cure mechanism under200℃. DMA, TGA, mechanical properties and water uptake measurement were used to monitor the effect of the change in the PPBMI/D ABPA molar ratio on the various properties. The results indicate the storage modulus (G’), glass transition temperature (To), thermostability and char yield were increased and the water uptake was reduced with the increase of PPBMI in the PPBMI/D ABPA systems.PPBMI was introduced into the MBMI/DABPA system, and the effect of MBMI/PPBMI molar ratio on the properties of the modified resins was investigated at the molar ratio of maleimide to allyl groups of1:0.87. As the PPBMI content was increased, the G’ in the rubbery region and To were decreased, but the thermal stability and moisture resistance were enhanced. The flexural strength and impact strength firstly increased and then decreased, but the flexural modulus always increased with increasing PPBMI content. The fracture micrographs exhibited some defects in the cured networks with higher PPBMI content.The PPBMI/DDS/E-51co-curing systems were prepared, and the resin systems were divided into E-51modified PPBMI/DDS systems and PPBMI modified E-51/DDS systems on the basis of the different fundamental ingredients. The cure mechanism of modified resins was analyzed by means of FTIR and DSC, the results indicate that the E-51modified PPBMI/DDS systems have different cure mechanism depending on composition of modified systems and the main reaction occurring during the cure of PPBMI modified E-51/DDS systems include epoxy cure and Michael addition between PPBMI and DDS. DMA, TGA, mechanical properties and water uptake measurement were used to study the properties of two modified resins. For E-51modified PPBMI/DDS systems, heat resistance, thermostability and moisture resistance were decreased with increasing content of E-51, but the impact strength was improved. For PPBMI modified E-51/DDS systems, heat resistance decreased, but thermal stability, moisture resistance, flexural strength and modulus were enhenced as an increase of PPBMI; the impact strength firstly increased and then decreased with the PPBMI content and the5%PPBMI modified system showed maximum value.更多还原