聚醚砜增韧环氧树脂体系及其碳纤维复合材料的研究

发布时间：2018-12-17 08:18

【摘要】：环氧树脂是最重要的热固性树脂之一。高性能纤维增强环氧树脂基复合材料因为具有高的比强度、比模量,在航空航天、陆上交通、机械等领域得到广泛应用,但韧性差是其发展瓶颈。因此,设计和制备高韧性环氧树脂基体一直是先进复合材料的研究热点。目前几种常用的改性方法是在环氧树脂中加入橡胶弹性体或在交联网络中加入柔性链段,这种方法在提高韧性的同时也会降低树脂基体的强度、模量和耐热性能。采用高模量、高韧性和热稳定性佳的热塑性聚合物如聚醚砜(Polyether sulfone,PES),作为增韧相来改性环氧树脂体系,有望成为新的有效途径。本文主要研究了PES改性环氧树脂E51(即PES/E51体系)的溶解和固化行为,及其浇注体与以此为基体的碳纤维复合材料的力学性能和相结构等。对PES/E51体系的溶解性能进行了研究。通过热台偏光显微镜观察发现,在无有机溶剂辅助时,PES在120℃下经过30 min可完全溶解于E51中;进一步加入固化剂DETD后,可形成溶液形式的PES/E51/DETD树脂体系。通过等温和非等温DSC分析,确定PES/E51/DETD树脂体系的固化制度为120℃下保温2 h。PES的加入对PES/E51/DETD树脂体系固化过程中的表观活化能有一定的影响,当PES加入量为10 wt.%时,表观活化能最小,为50.96 k J/mol。不同PES含量的PES/E51/DETD树脂体系制备浇注体样条,并进行力学性能、热性能测试和相结构表征。结果表明,随着PES含量的增加,浇注体的力学性能呈现先上升后降低的趋势,当PES的含量为15 wt.%时,PES/E51/DETD树脂体系浇注体的拉伸强度和冲击强度达到最大值,分别为48.06 MPa和25.8 k J/m2,是未改性环氧树脂浇注体的2.3倍和3倍,表明树脂体系强度和韧性等力学性能获得大幅提高。在浇注体的微观结构中,PES和E51均呈现双连续相。当PES含量超过15 wt.%时体系微观结构出现相反转,根据固化放热峰的变化趋势可知,在相反转发生之前,PES的加入对PES/E51/DETD树脂体系的固化起促进作用,相反转之后则起到阻碍作用。采用模压成型和VARI成型工艺制备了碳纤维增强PES/E51/DETD树脂体系复合材料板材。通过流变性能研究发现,PES含量分别为0 wt.%和15 wt.%的PES/E51/DETD树脂体系的粘度均达到模压成型和VARI成型的要求;在涂覆或灌注等实验操作所需的80℃下,两种PES含量的树脂体系粘度均具有良好的稳定性。复合材料的力学性能测试结果表明,当PES加入量为15 wt.%时,模压成型制备的碳纤维增强PES/E51/DETD复合材料的韧性与未改性体系作基体的复合材料相比有明显提升,断裂吸收能增加43.3%。然而,由于PES的加入使环氧树脂体系粘度升高,VARI成型对树脂粘度更加敏感,导致复合材料层间结合力下降,综合力学性能反而有所降低。
[Abstract]:Epoxy resin is one of the most important thermosetting resins. High performance fiber reinforced epoxy matrix composites have been widely used in aerospace, land transportation, machinery and other fields because of their high specific strength and specific modulus, but poor toughness is the bottleneck of their development. Therefore, the design and preparation of high-toughness epoxy resin matrix has been the research hotspot of advanced composites. At present, several common modification methods are to add rubber elastomer in epoxy resin or flexible segment in crosslinking network. This method can not only improve toughness but also reduce the strength, modulus and heat resistance of resin matrix. Using thermoplastic polymers such as polyether sulfone (Polyether sulfone,PES) as toughening phase to modify epoxy resin system with high modulus, high toughness and good thermal stability is expected to be a new effective way. The dissolution and curing behavior of epoxy resin E51 (PES/E51 system) modified by PES and the mechanical properties and phase structure of the cast and carbon fiber composites based on E51 were studied in this paper. The solubility of PES/E51 system was studied. The results of polarizing microscope show that PES can be completely dissolved in E51 after 30 min at 120 鈩，

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