本文關(guān)鍵詞： 碳纖維 多尺度增強體 活性自由基聚合 界面 分子模擬　出處：《南昌航空大學》2017年碩士論文　論文類型：學位論文

【摘要】：碳纖維增強樹脂基復合材料(carbon fiber reinforced polymer composites,CFRP)具有高的比模量和比強度、可設(shè)計性好等優(yōu)點,被廣泛應用于航天航空、武器裝備等軍用領(lǐng)域以及汽車、體育用品、建筑材料等民用領(lǐng)域。但由于碳纖維需要在惰性氣氛中經(jīng)過高溫石墨化處理,使得碳纖維表面活性基團少,惰性大,因此與樹脂基體的浸潤性以及粘接性較差,界面處容易出現(xiàn)破壞,嚴重影響復合材料的整體性能的發(fā)揮以及使用壽命。本文首先通過活性自由基聚合法在碳纖維表面引入梳型聚合物以制得梳型聚合物/碳纖維多尺度增強體,然后以環(huán)氧樹脂為基體,制得多尺度增強體/環(huán)氧樹脂復合材料,并對得到復合材料力學性能及界面性能進行表征,研究梳型聚合物的引入對復合材料性能的影響。同時,通過分子模擬構(gòu)建復合材料模型,從界面能角度研究碳纖維多尺度增強體對復合材料界面的影響。具體完成內(nèi)容如下:(1)通過丙酮-硝酸法和硅烷偶聯(lián)劑(KH550)的水解縮合反應對原始碳纖維(CF-Raw)進行表面預處理,得到硅烷偶聯(lián)劑接枝碳纖維(CF-KH550),然后通過酯化反應將鏈轉(zhuǎn)移劑錨固到碳纖維表面;最后,通過可逆加成-斷裂鏈轉(zhuǎn)移聚合(RAFT)以及原子轉(zhuǎn)移自由基聚合將梳型聚合物(poly(4-vinylbenzyl chloride-g-glycidyl methacrylate),P(VBC-g-GMA))接枝在碳纖維表面,制得梳型聚合物接枝碳纖維多尺度增強體(CF-P(VBC-g-GMA))。通過傅里葉紅外吸收光譜儀(FT-IR)、綜合熱分析儀(TGA)、X射線光電子能譜(XPS)等對得到的碳纖維多尺度增強體進行表征,結(jié)果表明梳型聚合物成功接枝在碳纖維表面,且接枝率為26.37%,場發(fā)射掃描電子顯微鏡(FE-SEM)觀察結(jié)果表明CF-P(VBC-g-GMA)表面被聚合物包覆,氧化過程中造成的凹槽被修復。(2)以不同改性階段的碳纖維為增強體,雙酚A型環(huán)氧樹脂(E-51)為基體,三乙烯基四胺(TETA)為固化劑,通過熱壓工藝制備出復合材料。對得到的復合材料的力學性能進行表征,結(jié)果表明:梳型聚合物的引入可明顯改善復合材料的力學性能和界面性能,與未改性碳纖維增強復合材料相比,CF-P(VBC-g-GMA)的單絲拉伸強度和復絲拉伸強度分別升高22.00%和14.25%;復合材料的彎曲強度提升23.70%;層間剪切強度(ILSS)提升了31.29%。而界面剪切強度(IFSS)則更是提高了101.88%。場發(fā)射掃描電鏡結(jié)果顯示,CF-Raw/環(huán)氧樹脂復合材料斷口處纖維拔出較多,且被拔出的纖維表面光滑,而CF-P(VBC-g-GMA)/環(huán)氧樹脂復合材料的斷口僅有少量的纖維被拔出,且拔出纖維的表面黏附有大量基體樹脂,表明CF-P(VBC-g-GMA)與樹脂間的黏附作用增強,界面強度提高。(3)借助Materials Studio(MS)構(gòu)建復合材料模型,從原子尺度出發(fā)研究界面層對復合材料強度的影響。以Forcite為運算環(huán)境進行分子力學計算,完成結(jié)構(gòu)的幾何優(yōu)化;在NVT系綜,Universal力場中進行分子動力學計算。結(jié)果表明,復合材料中對界面能變化貢獻最大的是體系的交互作用,CF-P(VBC-g-GMA)/環(huán)氧樹脂復合材料體系中界面處碳纖維與樹脂的間距為16.84?,比CF-Raw/環(huán)氧樹脂復合材料體系降低了23.42%。界面結(jié)構(gòu)中間距減小,碳纖維與樹脂間的相互作用增強,復合材料的界面強度增強,宏觀力學強度提高。
[Abstract]:Carbon fiber reinforced resin matrix composites (carbon fiber reinforced polymer composites, CFRP) has high specific modulus and specific strength, flexibility in design and is widely used in aerospace, weapons and equipment such as military field and automobile, sports goods, civil building materials. But because of the carbon fiber after high temperature graphitization treatment in an inert atmosphere, the surface of activated carbon fiber group, inert, so the resin and the wettability and adhesion at the interface is poor, prone to failure, seriously affect the overall performance of the composite material of the play and life. Firstly, through the activity of free radical polymerization on the surface of carbon fibers by comb polymer to prepare comb polymer / carbon fiber multi scalereinforcement, then with epoxy resin as matrix and preparation of multi-scale reinforcement / epoxy resin composite material, and the The mechanical properties of the composites and interfacial properties were characterized by introducing the research of comb polymers on the properties of the composite materials. At the same time, through the construction of molecular simulation model of composite material, carbon fiber can enhance the multi-scale study angle influence on the composite interface from the interface. The concrete contents are as follows: (1) by acetone - nitrate method and silane coupling agent (KH550) hydrolysis and condensation reaction of the original carbon fiber (CF-Raw) was pretreated by silane coupling agent grafted carbon fiber (CF-KH550), and then the chain transfer agent anchored to the surface of carbon fiber by esterification; finally, addition fragmentation chain transfer polymerization by reversible (RAFT) and the atom transfer radical polymerization will comb polymer (poly (4-vinylbenzyl chloride-g-glycidyl methacrylate), P (VBC-g-GMA)) was grafted on the surface of carbon fiber, preparation of comb polymer grafted carbon fiber scales increase Strong body (CF-P (VBC-g-GMA)). By means of Fourier transform infrared absorption spectrometer (FT-IR), thermogravimetric analyzer (TGA), X ray photoelectron spectroscopy (XPS) on multi scale carbon fiber reinforcement were obtained, results showed that comb polymer was successfully grafted onto the carbon fiber surface, and the grafting rate was 26.37%, field emission scanning electron microscopy (FE-SEM) observation results showed that CF-P (VBC-g-GMA) surface was coated with polymer, resulting in groove oxidation process was repaired. (2) with different modification stages of carbon fiber as reinforcement, bisphenol A type epoxy resin (E-51) as matrix, three vinyl amine (TETA) four as curing agent, were prepared by hot pressing process of composite material were characterized, on the mechanical properties of composites. The results showed that the addition of comb polymer can significantly improve the mechanical properties and interfacial properties of the composites, and the unmodified carbon fiber reinforced composite material compared to CF -P (VBC-g-GMA) monofilament and multifilament tensile strength tensile strength were increased by 22% and 14.25%; the flexural strength of the composites increased by 23.70%; the interlaminar shear strength (ILSS) and 31.29%. to enhance the interfacial shear strength (IFSS) is improved by 101.88%. field emission scanning electron microscopy showed that CF-Raw/ epoxy resin composite fiber fracture pull out more, and pulled out the fiber surface is smooth, and the CF-P (VBC-g-GMA) / epoxy resin composite material fracture is only a small amount of fiber is pulled out, and pull out the surface of the fiber is adhered with matrix resin, showed that CF-P (VBC-g-GMA) and enhance the adhesion between the resin, the interface strength is increased. (3) with Materials Studio (MS) to construct the composite material model, the atomic scale study of interface layer on the strength of composite materials. The effects of using Forcite as the computing environment for molecular mechanics calculation, the geometric structure. ; in the NVT ensemble of molecular dynamics calculation of Universal force field. The results show that the composite material on the interface can change the largest contribution to the interaction system, CF-P (VBC-g-GMA) / epoxy resin composites interface between carbon fiber and resin at 16.84? CF-Raw/, ratio of epoxy resin composite material the system reduces the reduced spacing 23.42%. interface structure, enhance the interaction between carbon fibers and resin, enhance the interfacial strength, improve the mechanical strength.

【學位授予單位】：南昌航空大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TB332

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