【作者】 赵兴；

【导师】 李玲；

【作者基本信息】 中北大学 ， 材料学， 2008， 硕士

【摘要】 本文选择与BMI结构相似、分子量较低的刚性体（PEI）作为BMI的增韧剂,从PEI的分子结构入手,研究不同端基、不同分子结构PEI与改性BMI固化树脂体系相分离的关系,确定BMI分子复合材料形成的结构条件;研究不同端基、不同分子结构PEI与改性BMI固化树脂性能的关系,得到BMI分子复合材料最佳性能的分子组装元素。在BMI共聚单体RS中合成出8种不同结构的PEI,比较系统的研究了PEI分子结构对增韧效果的影响。在本实验选取范围内,对树脂增韧的最大贡献是在分子链中引入易于旋转的醚键,如刚性体DAEIa是由醚酐和醚胺合成的,链段中含有最多的醚键,其冲击强度为20.53 KJ/m2,与纯体系RS/BMI树脂相比,除具有相当的反应性、工艺性和耐热性外,韧性提高了104.89%。依据透光率、玻璃化转变与相分离的相关性,研究发现:非活性端基、主链刚性基团较多及提高极性侧基含量,均有利于PEI/RS/BMI树脂体系固化过程中相分离的发生和相分离速率的提高。相分离易削弱PEI对BMI树脂的改性效果,即PEI/RS/BMI固化物为均相结构时,PEI在提高固化物韧性和综合性能方面具有较大的优势。结合树脂的结构和断口形貌可知,改性BMI分子复合材料增韧机理属于微裂纹-剪切带、微裂纹的偏移和支化的共同作用结果。对各向同性混杂复合材料进行低速落重冲击实验可知:对于各向同性的复合材料层压板,空白体系RS/BMI的分层扩展阻力R为3.29 KJ/m²,临界分层冲击能量W₀为0.25J;增韧体系DAEIa/RS/BMI的分层扩展阻力R为5.43×10^-3 KJ/m²,临界分层冲击能量W₀为0.6J,显然增韧后大大提高了板材的层间断裂韧性。更多还原

【Abstract】 Imide oligmer with a similar molecular structure to BMI is selected for modification BMI resin. Based on the relations of different end groups、molecular structure of PEI on reaction-induced decomposition and performance of the curing resin, we can make sure the structure conditions and get the elements of optimum performance of BMI molecular composite.Eight different structure of PEI are polymerized in comonomer RS. we study the effect of the molecular structure of PEI on toughness of modification BMI resin. The greatest contribution to toughness in this paper is adding the ether linkage, e.g. modified BMI resin by DAEIa is synthesized by ODPA and DBPP has outstanding toughness, BMI molecular composite had better toughness besides equivalent reactivity, processing property and heat resisting property. The impact strength Compared with RS/BMI resin system improves 104.89% is 20.53 KJ/m2 in this paper.It benefits generating of phase separation and improving of the rate of phase separation to inactive end groups、more rigid groups in main chain and improve the content of polar latent groups. Phase separation weakens the modification effect.The toughening mechanism of BMI molecular composite is the complex foundation of microcrack-shear band、deviation and branching of microcrack.The isotropic composite laminate was tested through low speed drop-weight impact test. The delamination resistance of RS/BMI is 3.29×10^-3J/mm² and the delamination critical energy is 0.25 J; the delamination resistance of DAEIa/RS/BMI is 5.43×10^-3J/mm² and the delamination critical energy is 0.6 J, which is improved remarkably of the fracture toughness property.更多还原