【摘要】：碳纖維增強(qiáng)環(huán)氧樹(shù)脂基復(fù)合材料因其比重輕、比強(qiáng)度高、比剛度大、熱膨脹系數(shù)小、可設(shè)計(jì)性強(qiáng),同時(shí)還兼?zhèn)淠透g和抗疲勞等諸多優(yōu)點(diǎn),在許多領(lǐng)域應(yīng)用時(shí)很好地起到減輕結(jié)構(gòu)重量、降低成本、節(jié)約資源以及優(yōu)化工藝的作用。但是目前,碳纖維增強(qiáng)環(huán)氧樹(shù)脂基復(fù)合材料在實(shí)際工程應(yīng)用中仍然存在界面結(jié)合弱、易發(fā)生脆性斷裂等問(wèn)題。因此,如果能夠通過(guò)簡(jiǎn)單、經(jīng)濟(jì)、有效的方法對(duì)碳纖維表面進(jìn)行改性,并對(duì)樹(shù)脂基體進(jìn)行增韌改性,這些都必將有效改善復(fù)合材料容易分層和脆斷等問(wèn)題,這對(duì)提升碳纖維增強(qiáng)環(huán)氧樹(shù)脂基復(fù)合材料在多種載荷作用下的力學(xué)性能和穩(wěn)定性等具有十分重要的現(xiàn)實(shí)意義。本研究首先采用去離子水超聲、濃硝酸浸泡、濃硝酸超聲等不同方式對(duì)碳纖維表面改性的效果進(jìn)行了考察,最后優(yōu)選出了濃硝酸-超聲協(xié)同改性的方法,對(duì)碳纖維表面進(jìn)行了成功有效的改性,并對(duì)改性后碳纖維及其環(huán)氧樹(shù)脂基復(fù)合材料的結(jié)構(gòu)和性能進(jìn)行了詳細(xì)研究。其次,通過(guò)設(shè)計(jì)碳纖維平紋布的鋪層角度和順序,考察了不同鋪層方式下復(fù)合材料的力學(xué)性能,得到了力學(xué)性能較佳的復(fù)合材料鋪層設(shè)計(jì)方法。最后,我們用成本較低、簡(jiǎn)單易操作和效果顯著的液體丁腈橡膠(LNBR)和納米二氧化硅作為增韌劑,對(duì)復(fù)合材料增韌改性的效果進(jìn)行了研究。論文的主要研究?jī)?nèi)容和創(chuàng)新點(diǎn)如下:(1)用去離子水超聲、濃硝酸浸泡、濃硝酸超聲等對(duì)碳纖維進(jìn)行表面處理,研究了表面處理對(duì)碳纖維表面微結(jié)構(gòu)、表面化學(xué)組成、相結(jié)構(gòu)、復(fù)絲拉伸強(qiáng)度以及改性碳纖維增強(qiáng)環(huán)氧樹(shù)脂復(fù)合材料的結(jié)構(gòu)和力學(xué)性能的影響。研究結(jié)果表明:硝酸氧化和超聲處理對(duì)碳纖維表面進(jìn)行了有效改性,其中硝酸處理使碳纖維表面粗糙度和含氧官能團(tuán)數(shù)量顯著增大,超聲處理使碳纖維獲得了良好的分散性并使碳纖維比表面積和含氧官能團(tuán)增加。而硝酸-超聲協(xié)同處理使得碳纖維中的微晶尺寸變小,碳纖維表面活性增大。硝酸氧化與超聲空化相結(jié)合強(qiáng)化了碳纖維表面的氧化和刻蝕作用,從而增強(qiáng)了碳纖維與樹(shù)脂基體界面之間的“機(jī)械錨定”和“化學(xué)鍵合”作用,使碳纖維與樹(shù)脂之間的界面結(jié)合強(qiáng)度得以有效提高,從而顯著改善了復(fù)合材料的力學(xué)性能。(2)詳細(xì)考察了濃硝酸-超聲協(xié)同改性碳纖維過(guò)程中,處理溫度、超聲時(shí)間對(duì)改性后碳纖維的失重率、表面微觀形貌、表面化學(xué)結(jié)構(gòu)及元素含量、潤(rùn)濕性、復(fù)絲拉伸強(qiáng)度等的影響效果。研究結(jié)果表明:隨著硝酸-超聲處理溫度的升高和處理時(shí)間的延長(zhǎng),碳纖維表面變得更加粗糙、失重率逐漸增加而復(fù)絲拉伸強(qiáng)度不斷降低。同時(shí),碳纖維表面的含氧官能團(tuán)數(shù)量、活性基團(tuán)含量逐漸增加,從而使得碳纖維與環(huán)氧樹(shù)脂間的浸潤(rùn)性、反應(yīng)性、機(jī)械錨合作用和結(jié)合力增大,最終使改性碳纖維增強(qiáng)復(fù)合材料的力學(xué)性能得以顯著提高。綜合考慮不同條件改性后碳纖維及其增強(qiáng)復(fù)合材料的各方面性能,本研究確定了用硝酸-超聲協(xié)同改性碳纖維的最佳工藝條件為60℃/2h。(3)通過(guò)改變碳纖維平紋布的鋪層角度和鋪層順序,制備了五種不同鋪層方式的復(fù)合材料,并對(duì)它們的力學(xué)性能進(jìn)行了考察和對(duì)比分析。結(jié)果表明:隨著纖維鋪層角度和鋪層順序的變化,制備的復(fù)合材料力學(xué)性能各異,含有(±45)平紋布鋪層的復(fù)合材料,它們的拉伸斷裂伸長(zhǎng)率有一定幅度的提高,但它們的拉伸強(qiáng)度和拉伸模量明顯下降,復(fù)合材料的彎曲強(qiáng)度和彎曲模量也有較為明顯地下降,(±45)平紋布層數(shù)越多下降越明顯。最終綜合考慮,確定了拉伸和彎曲性能最佳時(shí)的鋪層方式為[(0,90)]4。(4)分別使用LNBR和納米二氧化硅對(duì)復(fù)合材料進(jìn)行了增韌改性研究,通過(guò)對(duì)比增韌劑在不同添加量時(shí)復(fù)合材料的力學(xué)性能,確定出各自的最佳添加量,并結(jié)合它們各自的增韌改性機(jī)理對(duì)實(shí)驗(yàn)數(shù)據(jù)進(jìn)行了深入分析。研究結(jié)果表示:這兩種增韌劑都可以對(duì)復(fù)合材料起到增韌補(bǔ)強(qiáng)的作用,二者在改善復(fù)合材料力學(xué)性能方面又有著各自突出的一面。我們發(fā)現(xiàn),適宜的LNBR對(duì)復(fù)合材料的彎曲性能改善效果顯著,復(fù)合材料的彎曲強(qiáng)度有了較大的提升,而適宜的納米二氧化硅對(duì)復(fù)合材料的拉伸性能提高較為突出,可以使復(fù)合材料的拉伸斷裂伸長(zhǎng)率、拉伸強(qiáng)度和拉伸模量得到較明顯的提高。
[Abstract]:Carbon fiber reinforced epoxy resin matrix composites have many advantages, such as light weight, high specific strength, high specific stiffness, low coefficient of thermal expansion, strong designability, corrosion resistance and fatigue resistance, etc. They play a good role in reducing structural weight, reducing costs, saving resources and optimizing process in many fields. There are still some problems in the application of fiber reinforced epoxy resin matrix composites, such as weak interfacial bonding and brittle fracture. Therefore, if the surface of carbon fiber can be modified by simple, economical and effective methods, and the resin matrix can be toughened, these will effectively improve the easy delamination and fracture of the composites. Brittleness and fracture of carbon fiber reinforced epoxy resin matrix composites have important practical significance for improving the mechanical properties and stability of carbon fiber reinforced epoxy resin matrix composites under various loads. The method of concentrated nitric acid-ultrasonic synergistic modification was optimized, and the surface of carbon fiber was successfully and effectively modified. The structure and properties of the modified carbon fiber and its epoxy resin matrix composites were studied in detail. Secondly, the composite materials under different laying methods were investigated by designing the laying angle and sequence of carbon fiber plain cloth. Finally, the effect of toughening modification of composites was studied by using liquid nitrile-butadiene rubber (LNBR) and nano-silica as toughening agents with low cost, easy operation and remarkable effect. The following: (1) Carbon fibers were treated by ultrasonic wave in deionized water, soaked in concentrated nitric acid and ultrasonic wave in concentrated nitric acid. The effects of surface treatment on the surface microstructure, surface chemical composition, phase structure, tensile strength of carbon fibers and the structure and mechanical properties of carbon fiber reinforced epoxy resin composites were studied. The surface of carbon fibers was effectively modified by acid oxidation and ultrasonic treatment. Nitric acid treatment significantly increased the surface roughness and the number of oxygen-containing functional groups of carbon fibers. Ultrasonic treatment made carbon fibers disperse well and increased the specific surface area and oxygen-containing functional groups of carbon fibers. The combination of nitric acid oxidation and ultrasonic cavitation strengthens the oxidation and etching on the surface of carbon fibers, thus enhancing the "mechanical anchoring" and "chemical bonding" between the interface between carbon fibers and resin matrix, and effectively improving the bonding strength between carbon fibers and resin. (2) The effects of temperature and ultrasonic time on the weight loss, surface micro-morphology, surface chemical structure and element content, wettability and tensile strength of carbon fibers were investigated in detail. With the increase of nitric acid-ultrasonic treatment temperature and treatment time, the surface of carbon fiber becomes more rough, the weight loss rate increases gradually, and the tensile strength of composite fiber decreases continuously. The mechanical properties of the modified carbon fiber reinforced composites were improved significantly with the increase of the combination and binding force. Considering the properties of the modified carbon fiber and its reinforced composites under different conditions, the optimum technological conditions for the modification of carbon fiber by nitric acid-ultrasonic synergism were determined to be 60 C/2h. (3) By changing the carbon fiber. The results show that the mechanical properties of the composites are different with the change of the fiber laying angle and the laying sequence, and the composites containing (+45) plain cloth layers have different mechanical properties. Their tensile elongation at break increased to a certain extent, but their tensile strength and modulus decreased obviously. The bending strength and modulus of the composites also decreased significantly. The more the number of layers of (+45) plain weave, the more obvious the decrease was. Finally, the optimum laying mode for tensile and bending properties was determined to be [(0,90). (4) The composites were toughened with LNBR and nano-silica respectively. The mechanical properties of the composites with different toughening agents were compared and the optimum addition was determined. The experimental data were analyzed in detail according to their toughening mechanism. Both of the toughening agents can play a toughening and reinforcing role in the composite, and both of them have their own prominent aspects in improving the mechanical properties of the composite. The tensile strength and modulus of the composites can be improved obviously by increasing the tensile properties of the composites.
【學(xué)位授予單位】：蘭州交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TQ327.3;TB332

【參考文獻(xiàn)】

相關(guān)期刊論文 前3條

1 杜慧玲,齊錦剛,龐洪濤,萬(wàn)怡灶,王玉林;表面處理對(duì)碳纖維增強(qiáng)聚乳酸材料界面性能的影響[J];材料保護(hù);2003年02期

2 陳景昊;孫秦;范學(xué)領(lǐng);;基于共享鋪層融合技術(shù)復(fù)合材料層壓板鋪層順序優(yōu)化設(shè)計(jì)[J];固體火箭技術(shù);2012年06期

3 劉志中,王新靈,羅蔭培,唐小真;環(huán)氧樹(shù)脂增韌改性研究進(jìn)展[J];中國(guó)塑料;1998年06期

，

本文編號(hào)：2250451