苎麻增强聚丙烯复合材料界面性能研究
发布时间：2018-11-03 17:57
【摘要】：近年来天然植物纤维增强热塑性树脂复合材料受到越来越多的关注,然而天然纤维的亲水性导致其与大部分热塑性基体(尤其是聚烯烃)相容性较差,如何改善此类复合材料的界面粘结问题,是此类复合材料研究的一个主要方面。我国盛产的苎麻纤维力学性能优良、成本适中,因此苎麻增强聚丙烯树脂复合材料作为天然纤维热塑性树脂复合材料之一,在许多领域具有较大的应用潜力。由于苎麻纤维和聚丙烯树脂本身固有的特性,造成两者之间的界面粘结性较弱,从而影响了其复合材料的机械性能。本课题将以苎麻增强聚丙烯复合材料为研究对象,通过聚合物共混改性、等离子体处理纤维表面改性和乳液聚合物改性三种不同的界面改性方法改善复合材料的界面性能,并通过建立理论模型和有限元模型分析影响复合材料界面性能的因素,比对实验结果,为制备有可调节性能界面的天然纤维热塑性复合材料提供思路和方法。本课题首先采用EVA(乙烯-乙酸乙烯共聚物)和PP(聚丙烯)共混的方法对苎麻增强聚丙烯复合材料的界面进行改性。实验表明添加EVA不仅对聚丙烯起到了增韧作用,同时EVA又起到和苎麻纤维连接的偶联剂的作用,对复合材料的界面性能有显著影响。随着EVA添加比例的增加,其混合体系的拉伸模量和拉伸强度明显下降,但其弯曲模量和弯曲强度却有增加的趋势。通过界面剪切性能测试得出,随着EVA比例的增加,界面剪切强度先增加后减小,在8%的比例含量时界面剪切强度最大。其次采用丙烯和丙烷气体等离子体处理改性苎麻纤维对苎麻增强聚丙烯复合材料的界面进行了改善和提高。发现苎麻纤维表面粗糙度的提高和表面烯烃基团或聚丙烯分子链的接枝数量是改善纤维表面性能的主要影响因素。在丙烯气体等离子体处理中,随着时间的增加,界面剪切强度先增加后减小,其中在1分钟的处理条件下界面性能最好,比原苎麻试样的实验结果提高36.4%。与丙烷气体等离子体处理相比,丙烯气体等离子体处理对苎麻纤维聚丙烯复合材料界面剪切性能具有更好的改善和提高。第三,配置了五种玻璃化温度的丙烯酸酯共聚乳液浸泡苎麻,对苎麻增强聚丙烯复合材料界面进行改性。实验结果表明,经丙烯酸酯共聚乳液处理后的苎麻纤维水接触角明显增大,从原来的66.76o增加到85o以上。随着乳液玻璃化温度的增加,复合材料界面剪切强度逐渐增加,在玻璃化温度为83℃时,剪切力提高47.07%,然后随着玻璃化温度增加界面剪切强度开始下降。浸泡过的纱线强度比原纱线强度大,并且随着乳液浓度增加强度先增加后减小,在15%时达到最大值,浸泡过的织物也有同样的规律。最后,对采用以上三种不同的界面改性方法制备了三种苎麻增强聚丙烯复合材料,进行了其弯曲性能和拉伸性能的测试,分析比较了不同处理方法和处理条件的弯曲载荷-挠度曲线和拉伸应力-应变曲线。结果表明,三种改性方法都能提高苎麻聚丙烯复合材料界面粘结强度。其中用乳液法处理得到的复合材料拉伸强度和弯曲强度提高最多,而EVA/PP共混法处理的复合材料拉伸和弯曲强度提高最少。等离子体处理方法对弯曲强度提高的程度与EVA/PP共混法相近。课题还建立了基于改性界面的单纤维抽拔理论模型,推导了抽拔力方程,并根据方程定性的讨论了影响复合材料界面性能的因素。通过改变粘结点的个数或者包埋长度(等效为连接键强度)改变复合材料的界面强度。建立了微滴包埋抽拔实验的有限元模型,讨论了不同纤维头端位移下微滴、纤维和界面的应力分布,得到了抽拔过程中界面的破坏形态,分析了材料不同性能条件下对界面的影响,考察了界面的破坏机理。
[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，
本文编号：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，
本文编号：2308530
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