【摘要】：環(huán)氧樹脂是最重要的熱固性樹脂之一。高性能纖維增強環(huán)氧樹脂基復合材料因為具有高的比強度、比模量,在航空航天、陸上交通、機械等領域得到廣泛應用,但韌性差是其發(fā)展瓶頸。因此,設計和制備高韌性環(huán)氧樹脂基體一直是先進復合材料的研究熱點。目前幾種常用的改性方法是在環(huán)氧樹脂中加入橡膠彈性體或在交聯(lián)網(wǎng)絡中加入柔性鏈段,這種方法在提高韌性的同時也會降低樹脂基體的強度、模量和耐熱性能。采用高模量、高韌性和熱穩(wěn)定性佳的熱塑性聚合物如聚醚砜(Polyether sulfone,PES),作為增韌相來改性環(huán)氧樹脂體系,有望成為新的有效途徑。本文主要研究了PES改性環(huán)氧樹脂E51(即PES/E51體系)的溶解和固化行為,及其澆注體與以此為基體的碳纖維復合材料的力學性能和相結(jié)構(gòu)等。對PES/E51體系的溶解性能進行了研究。通過熱臺偏光顯微鏡觀察發(fā)現(xiàn),在無有機溶劑輔助時,PES在120℃下經(jīng)過30 min可完全溶解于E51中;進一步加入固化劑DETD后,可形成溶液形式的PES/E51/DETD樹脂體系。通過等溫和非等溫DSC分析,確定PES/E51/DETD樹脂體系的固化制度為120℃下保溫2 h。PES的加入對PES/E51/DETD樹脂體系固化過程中的表觀活化能有一定的影響,當PES加入量為10 wt.%時,表觀活化能最小,為50.96 k J/mol。不同PES含量的PES/E51/DETD樹脂體系制備澆注體樣條,并進行力學性能、熱性能測試和相結(jié)構(gòu)表征。結(jié)果表明,隨著PES含量的增加,澆注體的力學性能呈現(xiàn)先上升后降低的趨勢,當PES的含量為15 wt.%時,PES/E51/DETD樹脂體系澆注體的拉伸強度和沖擊強度達到最大值,分別為48.06 MPa和25.8 k J/m2,是未改性環(huán)氧樹脂澆注體的2.3倍和3倍,表明樹脂體系強度和韌性等力學性能獲得大幅提高。在澆注體的微觀結(jié)構(gòu)中,PES和E51均呈現(xiàn)雙連續(xù)相。當PES含量超過15 wt.%時體系微觀結(jié)構(gòu)出現(xiàn)相反轉(zhuǎn),根據(jù)固化放熱峰的變化趨勢可知,在相反轉(zhuǎn)發(fā)生之前,PES的加入對PES/E51/DETD樹脂體系的固化起促進作用,相反轉(zhuǎn)之后則起到阻礙作用。采用模壓成型和VARI成型工藝制備了碳纖維增強PES/E51/DETD樹脂體系復合材料板材。通過流變性能研究發(fā)現(xiàn),PES含量分別為0 wt.%和15 wt.%的PES/E51/DETD樹脂體系的粘度均達到模壓成型和VARI成型的要求;在涂覆或灌注等實驗操作所需的80℃下,兩種PES含量的樹脂體系粘度均具有良好的穩(wěn)定性。復合材料的力學性能測試結(jié)果表明,當PES加入量為15 wt.%時,模壓成型制備的碳纖維增強PES/E51/DETD復合材料的韌性與未改性體系作基體的復合材料相比有明顯提升,斷裂吸收能增加43.3%。然而,由于PES的加入使環(huán)氧樹脂體系粘度升高,VARI成型對樹脂粘度更加敏感,導致復合材料層間結(jié)合力下降,綜合力學性能反而有所降低。
[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，

本文編號：2383945