苧麻增強聚丙烯復(fù)合材料界面性能研究
發(fā)布時間：2018-11-03 17:57
【摘要】：近年來天然植物纖維增強熱塑性樹脂復(fù)合材料受到越來越多的關(guān)注,然而天然纖維的親水性導(dǎo)致其與大部分熱塑性基體(尤其是聚烯烴)相容性較差,如何改善此類復(fù)合材料的界面粘結(jié)問題,是此類復(fù)合材料研究的一個主要方面。我國盛產(chǎn)的苧麻纖維力學(xué)性能優(yōu)良、成本適中,因此苧麻增強聚丙烯樹脂復(fù)合材料作為天然纖維熱塑性樹脂復(fù)合材料之一,在許多領(lǐng)域具有較大的應(yīng)用潛力。由于苧麻纖維和聚丙烯樹脂本身固有的特性,造成兩者之間的界面粘結(jié)性較弱,從而影響了其復(fù)合材料的機械性能。本課題將以苧麻增強聚丙烯復(fù)合材料為研究對象,通過聚合物共混改性、等離子體處理纖維表面改性和乳液聚合物改性三種不同的界面改性方法改善復(fù)合材料的界面性能,并通過建立理論模型和有限元模型分析影響復(fù)合材料界面性能的因素,比對實驗結(jié)果,為制備有可調(diào)節(jié)性能界面的天然纖維熱塑性復(fù)合材料提供思路和方法。本課題首先采用EVA(乙烯-乙酸乙烯共聚物)和PP(聚丙烯)共混的方法對苧麻增強聚丙烯復(fù)合材料的界面進行改性。實驗表明添加EVA不僅對聚丙烯起到了增韌作用,同時EVA又起到和苧麻纖維連接的偶聯(lián)劑的作用,對復(fù)合材料的界面性能有顯著影響。隨著EVA添加比例的增加,其混合體系的拉伸模量和拉伸強度明顯下降,但其彎曲模量和彎曲強度卻有增加的趨勢。通過界面剪切性能測試得出,隨著EVA比例的增加,界面剪切強度先增加后減小,在8%的比例含量時界面剪切強度最大。其次采用丙烯和丙烷氣體等離子體處理改性苧麻纖維對苧麻增強聚丙烯復(fù)合材料的界面進行了改善和提高。發(fā)現(xiàn)苧麻纖維表面粗糙度的提高和表面烯烴基團或聚丙烯分子鏈的接枝數(shù)量是改善纖維表面性能的主要影響因素。在丙烯氣體等離子體處理中,隨著時間的增加,界面剪切強度先增加后減小,其中在1分鐘的處理條件下界面性能最好,比原苧麻試樣的實驗結(jié)果提高36.4%。與丙烷氣體等離子體處理相比,丙烯氣體等離子體處理對苧麻纖維聚丙烯復(fù)合材料界面剪切性能具有更好的改善和提高。第三,配置了五種玻璃化溫度的丙烯酸酯共聚乳液浸泡苧麻,對苧麻增強聚丙烯復(fù)合材料界面進行改性。實驗結(jié)果表明,經(jīng)丙烯酸酯共聚乳液處理后的苧麻纖維水接觸角明顯增大,從原來的66.76o增加到85o以上。隨著乳液玻璃化溫度的增加,復(fù)合材料界面剪切強度逐漸增加,在玻璃化溫度為83℃時,剪切力提高47.07%,然后隨著玻璃化溫度增加界面剪切強度開始下降。浸泡過的紗線強度比原紗線強度大,并且隨著乳液濃度增加強度先增加后減小,在15%時達到最大值,浸泡過的織物也有同樣的規(guī)律。最后,對采用以上三種不同的界面改性方法制備了三種苧麻增強聚丙烯復(fù)合材料,進行了其彎曲性能和拉伸性能的測試,分析比較了不同處理方法和處理條件的彎曲載荷-撓度曲線和拉伸應(yīng)力-應(yīng)變曲線。結(jié)果表明,三種改性方法都能提高苧麻聚丙烯復(fù)合材料界面粘結(jié)強度。其中用乳液法處理得到的復(fù)合材料拉伸強度和彎曲強度提高最多,而EVA/PP共混法處理的復(fù)合材料拉伸和彎曲強度提高最少。等離子體處理方法對彎曲強度提高的程度與EVA/PP共混法相近。課題還建立了基于改性界面的單纖維抽拔理論模型,推導(dǎo)了抽拔力方程,并根據(jù)方程定性的討論了影響復(fù)合材料界面性能的因素。通過改變粘結(jié)點的個數(shù)或者包埋長度(等效為連接鍵強度)改變復(fù)合材料的界面強度。建立了微滴包埋抽拔實驗的有限元模型,討論了不同纖維頭端位移下微滴、纖維和界面的應(yīng)力分布,得到了抽拔過程中界面的破壞形態(tài),分析了材料不同性能條件下對界面的影響,考察了界面的破壞機理。
[Abstract]:In recent years, natural plant fiber reinforced thermoplastic resin composites have attracted more and more attention, however, the hydrophilicity of natural fibers results in poor compatibility with most thermoplastic substrates, particularly polyolefins, how to improve the interfacial bonding problem of such composites, is a major aspect of this kind of composite material research. As one of the natural fiber thermoplastic resin composites, the hemp fiber reinforced polypropylene resin composite material has great potential for application in many fields. Due to the inherent characteristics of the linen fiber and the polypropylene resin, the interfacial bond between them is weak, thus affecting the mechanical properties of the composite material. In this paper, the interfacial properties of composites were improved by blending modification of polymer blend, surface modification of plasma processing fiber and modified emulsion polymerization. By establishing the theoretical model and the finite element model, the factors affecting the interfacial properties of the composites are analyzed. The results of experiments are compared with those of the natural fiber thermoplastic composites with the adjustable energy interface. In this paper, EVA (ethylene-vinyl acetate copolymer) and PP (polypropylene) blend were used to modify the interface of polypropylene composite. The experimental results show that EVA not only plays a toughening role in PP, but also plays an important role in the interface performance of the composites. With the addition of EVA, the tensile modulus and tensile strength of the hybrid system decreased significantly, but their bending modulus and bending strength tended to increase. The shear strength of the interface decreases with the increase of the ratio of EVA, and the interfacial shear strength is the most when the ratio of EVA is 8%. Secondly, propylene and propane gas plasma treatment were used to improve and improve the interface of modified linen fiber reinforced polypropylene composites. It was found that the improvement of surface roughness and the grafting number of surface olefin groups or polypropylene molecular chains were the main factors to improve the fiber surface properties. In the process of propylene gas plasma treatment, the shear strength of the interface decreases with the increase of time, in which the interface performance is better at 1 minute, and the experimental result is improved by 36. 4%. Compared with the propane gas plasma treatment, the propylene gas plasma treatment has better improvement and improvement on the interfacial shear properties of the linen fiber polypropylene composite material. and thirdly, the acrylic ester copolymer emulsion with five glass transition temperatures is arranged to be soaked in hemp, and the interface of the flax-reinforced polypropylene composite material is modified. The experimental results show that the contact angle of the fibrillated fibers treated by the acrylic ester copolymer emulsion is obviously increased, and the water contact angle is increased to more than 85o from the original 66. 76o. With the increase of the glass transition temperature of the emulsion, the shear strength of the interface of the composite material gradually increased. When the glass transition temperature was 83 鈩，
本文編號：2308530
[Abstract]:In recent years, natural plant fiber reinforced thermoplastic resin composites have attracted more and more attention, however, the hydrophilicity of natural fibers results in poor compatibility with most thermoplastic substrates, particularly polyolefins, how to improve the interfacial bonding problem of such composites, is a major aspect of this kind of composite material research. As one of the natural fiber thermoplastic resin composites, the hemp fiber reinforced polypropylene resin composite material has great potential for application in many fields. Due to the inherent characteristics of the linen fiber and the polypropylene resin, the interfacial bond between them is weak, thus affecting the mechanical properties of the composite material. In this paper, the interfacial properties of composites were improved by blending modification of polymer blend, surface modification of plasma processing fiber and modified emulsion polymerization. By establishing the theoretical model and the finite element model, the factors affecting the interfacial properties of the composites are analyzed. The results of experiments are compared with those of the natural fiber thermoplastic composites with the adjustable energy interface. In this paper, EVA (ethylene-vinyl acetate copolymer) and PP (polypropylene) blend were used to modify the interface of polypropylene composite. The experimental results show that EVA not only plays a toughening role in PP, but also plays an important role in the interface performance of the composites. With the addition of EVA, the tensile modulus and tensile strength of the hybrid system decreased significantly, but their bending modulus and bending strength tended to increase. The shear strength of the interface decreases with the increase of the ratio of EVA, and the interfacial shear strength is the most when the ratio of EVA is 8%. Secondly, propylene and propane gas plasma treatment were used to improve and improve the interface of modified linen fiber reinforced polypropylene composites. It was found that the improvement of surface roughness and the grafting number of surface olefin groups or polypropylene molecular chains were the main factors to improve the fiber surface properties. In the process of propylene gas plasma treatment, the shear strength of the interface decreases with the increase of time, in which the interface performance is better at 1 minute, and the experimental result is improved by 36. 4%. Compared with the propane gas plasma treatment, the propylene gas plasma treatment has better improvement and improvement on the interfacial shear properties of the linen fiber polypropylene composite material. and thirdly, the acrylic ester copolymer emulsion with five glass transition temperatures is arranged to be soaked in hemp, and the interface of the flax-reinforced polypropylene composite material is modified. The experimental results show that the contact angle of the fibrillated fibers treated by the acrylic ester copolymer emulsion is obviously increased, and the water contact angle is increased to more than 85o from the original 66. 76o. With the increase of the glass transition temperature of the emulsion, the shear strength of the interface of the composite material gradually increased. When the glass transition temperature was 83 鈩，
本文編號：2308530
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