PLA/热塑性淀粉和PLA/亚麻纤维可降解复合材料的性能研究

使用熔融共混方法,制备了PLA/热塑性淀粉(PLA/TPS)和PLA/亚麻纤维(PLA/FF)复合材料.研究结果表明,随着热塑性淀粉或者亚麻纤维用量的增加,PLA复合材料的拉伸强度和断裂伸长率都有所降低;而PLA的结晶速率呈现显著增大,并且晶粒细化;添加热塑性淀粉或者亚麻纤维,能够增加PLA复合材料的降解速率.     

The Manufacture of Structured Flax/Hemp Fiber Thermoplastic Composites and Its Flexural Properties

Flax and hemp fibers were used as reinforcing materials to commingle with polypropylene (PP) fiber to realize the mixture of two materials at the stage of yarn.Meanwhile,PP filaments were introduced to produce a corespun yarn with flax/PP as core and PP filament as outer sheath.The commingled yarns were woven into 2D fabric which was used as the prefabricated material.The composite laminates were prepared by hot press technology.The effects of manufacture technology, yam structure,and fiber weight fraction on flexural properties of composites were investigated.     

稀土处理对F-12纤维/环氧复合材料拉伸性能的影响

分别采用稀土改性剂（RES）、环氧氯丙烷（ECP）接枝改性方法对F-12芳纶纤维表面进行改性处理,研究这两种表面改性方法对F-12纤维的单丝拉伸强度及其环氧复合材料拉伸性能的影响．探讨了改性剂中稀土元素质量分数对复合材料拉伸性能的影响,并应用扫描电子显微镜（SEM）对复合材料拉伸试件的断口进行分析．结果表明,RES能很好地提高F-12纤维和环氧基体的界面结合力,从而明显地提高复合材料的拉伸性能,并且对纤维的单丝拉伸强度几乎没有影响．     

VARTM制备麻纤维增强环氧树脂复合材料研究

通过对黄麻纤维热处理、碱处理、硅烷偶联剂处理和异氰酸酯处理进行表面改性,并对改性黄麻纤维布进行热压工艺处理,最后采用VARTM成型工艺制备黄麻纤维增强环氧树脂复合材料,并对其性能进行了系统研究.通过扫描电镜(SEM)分析表明,热处理和碱处理的黄麻纤维增强环氧树脂复合材料的界面粘结未得到明显改善,而通过硅烷偶联剂和异氰酸酯处理的黄麻纤维增强环氧树脂复合材料的界面粘结性能得到了显著的提高.将硅烷偶联剂和异氰酸酯处理的黄麻纤维布通过热压处理不仅可以增加复合材料中黄麻纤维体积含量,而且可以提高复合材料的综合性能,复合材料力学性能研究表明,经硅烷偶联剂处理后的黄麻纤维增强复合材料拉伸强度、模量和弯曲强度分别提高了18.6%,71.4%和50.2%.经异氰酸酯处理的黄麻纤维增强复合材料的拉伸强度、模量和弯曲强度分别提高了16.3%,34.0%和50.3%.     

Mechanical and Thermal Properties of Apocynum and Ramie Fiber Mat Reinforced Polylactic Acid Composites

With the increasing awareness of environmental protection and rational utilization of resources, natural fiber reinforced composites have shown broad development prospects. Apocynum fiber, known as the "king of wild fiber", not only has moisture absorption, air permeability, and good mechanical properties but also has many health-related advantages such as antibacterial properties. In this study, four types of needle-punched Apocynum fiber and ramie fiber mat reinforced polylactic acid(PLA) composites were fabricated. Mechanical and thermal properties of the composites were tested and analyzed. The results showed that compared with those of the ramie fiber finish needle-punched mat reinforced composites, the tensile strength and the tensile modulus of Apocynum fiber finish needle-punched mat reinforced composites had increased by 15.3% and 60.1%, respectively. In comparison, the bending strength and the bending modulus were decreased by 21.8% and 7.6%, respectively. Moreover, compared with the Apocynum fiber finish needled-punched mat reinforced composites and the ramie fiber finish needle-punched mat reinforced composites, the Apocynum 50/ramie 50 finish needle-punched mat reinforced composites had the best tensile and bending properties. The after-fracture morphology was detected by a scanning electron microscope(SEM). The thermal properties of the composites were also characterized. It was found that the thermal properties of the four types of composites showed very similar behaviors.     

计及基体刚度的单向复合材料应力集中分析

提出了一种计及基体拉伸刚度效应的修正剪滞模型，用于研究单向纤维增强复合材料中由于纤维或基体破坏所引起的应力重分布问题。文中定量讨论了纤维／基体拉伸刚度比及纤维体积分数对断口邻近的纤维和基体的应力集中的影响。证实了当基体拉伸模量较低（如树脂基复合材料）及纤维体积分数较大时，可以忽略基体刚度对应力集中的影响；而对于其它情形（如陶瓷、金属基复合材料），就不可忽略基体刚度的影响。     

不同改性方法对竹塑复合材料拉伸性能的影响

研究了纳米碳酸钙浸渍改性对单根竹纤维表面碳酸钙附着情况、拉伸性能以及竹纤维/聚丙烯复合材料拉伸性能的影响,并将改性效果与纳米碳酸钙原位沉积改性进行对比。结果表明,纳米碳酸钙浸渍改性可以使碳酸钙颗粒均匀填充竹纤维表面微孔、褶皱等缺陷部位,附着的碳酸钙颗粒粒径均匀,分散性较好,附着量达到21.39%。经浸渍改性的单根竹纤维力学性能有所提高,拉伸强度、弹性模量、断裂伸长率分别提高了15.98%、22.15%和5.21%,但提高幅度低于原位沉积改性。分别将纳米碳酸钙浸渍、原位沉积改性竹纤维与聚丙烯薄膜制成竹塑复合材料,通过断面形貌观察发现两种改性方法均可改善竹纤维与聚丙烯的界面结合性能,复合材料拉伸性能相应提高,浸渍改性使复合材料拉伸强度和弹性模量分别提高了6.95%和15.80%,原位沉积改性分别提高18.68%和25.41%。虽然浸渍改性效果低于原位沉积改性,但工艺更简单。     

稀土处理对碳纤维增强聚四氟乙烯复合材料拉伸性能的影响

采用空气氧化、空气氧化后稀土改性和稀土改性对碳纤维表面进行处理,并研究了3种表面处理对碳纤维增强聚四氟乙烯(CF/PTFE)复合材料拉伸性能的影响.探讨了稀土含量对于复合材料拉伸性能的影响,并运用扫描电子显微镜(SEM)对复合材料拉伸试件的断口进行分析.结果表明:稀土处理能够有效地提高碳纤维与聚四氟乙烯基体的界面结合力,从而提高CF/PTFE复合材料的拉伸性能.当稀土元素在表面改性剂中的质量分数为0.3%时,CF/PTFE复合材料的拉伸性能最佳.     

PET废纤/竹原纤维增强不饱和聚酯复合材料的力学性能与吸水性能

采用平板模压成型方法制备聚对苯二甲酸乙二醇酯是(PET)废纤/竹原纤维增强不饱和聚酯复合材料,研究纤维梳理方式及不同质量比对复合材料力学性能与吸水性能的影响。结果表明:相同纤维比例、不同纤维梳理方式的复合材料拉伸强度无显著差异;纤维混合梳理的复合材料弯曲强度和弯曲模量均显著高于分别梳理的复合材料;纤维分别梳理的复合材料耐水性能优于纤维混合梳理的复合材料。动态机械热分析显示:复合材料储能模量随竹原纤维含量增加而增加,PET纤维含量的增加使复合材料阻尼效应增加。复合材料吸水动力学表明:水分在竹原纤维比例高且分别梳理的复合材料内部的扩散符合Fick定律;而水分在竹原纤维比例低且纤维混合梳理的复合材料内部的扩散行为不符合Fick定律。     

PET/PTT复合纤维工艺性能研究

分别测试与分析了3种不同比例PET／PTT复合纤维的热收缩性能、卷曲性能和拉伸弹性．测试结果比较得出，40／60纤维具有较大的热收缩率，50／50纤雏具有较好的卷曲率、卷曲牢度和拉伸弹性回复性能．     

Influence of alkaline treatment and fiber loading on the physical and mechanical properties of kenaf/polypropylene composites for variety of applications

Due to current trend and increasing interest towards natural based fiber products, Kenaf (Hibiscus cannabinus) fibers have been used for the developments of many products. Therefore, Kenaf fiber-reinforced composites have been widely used in engineering and industrial applications. The present work deals with the fabricating and characterization of untreated and treated kenaf/polypropylene (PP)-reinforced composites. Composites of PP reinforced with treated and untreated kenaf fibers were fabricated using the injection molding technique. Different fiber loadings of 10, 20, 30, 40, 50 wt% treated and untreated kenaf composites were also prepared. X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis (TGA) were performed on the treated, untreated kenaf fibers and kenaf/PP composites. Moreover, the alkaline-treated kenaf composites exhibit better physical, morphological, and mechanical properties because of the compatibility of kenaf with PP. However, variations in tensile and flexural properties depend on treatment and kenaf fiber contents. The percentage increase in the mechanical properties of the treated kenaf/PP composites relative to that of PP was also measured. In addition, 40 wt% kenaf fiber loading resulted in higher mechanical properties. By contrast, kenaf/PP composite with 50% fiber loading was not successfully prepared because of improper mixing and the burning of kenaf fibers in the PP matrix. To conclude, 40% kenaf/PP composites with superior physical and mechanical properties may be used in variety of applications such as automotive, sports, construction, animal bedding, and mass production industries.     

混杂钢纤维增强超高性能水泥基材料力学性能分析

采用平直型超细钢纤维与压痕型中长钢纤维混杂,系统研究了混杂比例对超高性能水泥基复合材料(UHPCC)流动性能、力学行为的影响,以及纤维外形对界面粘结力的影响.研究表明,随压痕型钢纤维掺入量增加,新拌浆体的流动度下降;在纤维体积率一定时,2种纤维等比例混杂,材料的抗压、拉伸、弯曲强度与弯曲韧性等力学性能为最佳;当水胶比固定时,压痕钢纤维与基体界面粘结力大于平直型超细钢纤维.试验还表明,2种纤维混杂在不同结构、不同尺度和不同时间层次对抑制裂缝的生成和扩展分别发挥作用,两者协同作用使材料总体力学性能显著提升.     

The Surface Properties and Tensile Strength of HSPE Fiber Treated by Controlling Oxidation in Chromic Acid

This work reported on the surface modification of high strength polyethylene(HSPE)fiber by chemical etching in chromic acid.The surface chemistry,the functional group contents, the wetting ability, the surface morphology and the tensile strength of modified fibers were investigated. The results show that, the surface roughness,surface wet properties and active functional group can be introduced on the HSPE fiber surface by this method,which will improve the interface adhesion in the composites, and the decrease of the tensile strength of modified fibers can be controlled.     

Manufacture of Flax Reinforced PP Laminates and Research on the Tensile Properties

Flax fiber was used to reinforce Polypropylene （PP） owing to its lower impact on environment and suitable mechanical behaviors. To overcome the difficulty of penetrating fibers due to the high viscosity of thermo-plastic resin, PP filaments wrapping around the linen yam produced commingled yams, which were woven into fabrics as preforms to make laminates by optimum hot-pressing technology. The effects of fiber volume fraction, fabric density and structure on tensile properties of composites were researched through analyzing the tensile test results and the scanning electronic microscope （SEM） micrographs of fracture surface. Conclusions are drawn that the properties of laminates with fiber volume fraction of 0.50 are better than those with the other two fractions. For plain structure, the tensile properties in warp direction decrease according to the increase of weft density while in weft direction increase. For different fabric structures, properties of laminates with structures of plain 3, twill 2/2 and twill 3/1 increase gradually. And properties in weft direction are prior to those in warp direction for each laminate.     

表面改性对三种天然纤维增强聚丙烯复合材料拉伸性能的对比研究

采用氨丙基三乙氧基硅烷(KH-550)、丙基三甲氧基硅烷(KH-570)以及马来酸酐接枝聚丙烯(MAPP)分别对纤维素、木屑和秸秆进行了表面改性处理,并分别制备了三种植物纤维增强聚丙烯复合材料,考察了复合材料的拉伸性能与改性方法、纤维类型及纤维含量的关系。结果表明,复合材料的拉伸强度随着纤维含量提高而降低;MAPP处理较硅烷偶联剂处理的纤维-基体界面粘接性能改善较大,其拉伸强度最大提高了50%,而断裂延伸率和断裂韧性也由于界面结合力提高而明显降低。     

碳纤维增强水泥复合材料的制备及性能

利用水热热压技术制备了碳纤维增强水泥复合材料，测定了材料的弯曲、压缩、劈裂拉伸、断裂韧性等力学性能，讨论了材料制备的工艺条件、显微结构等对材料力学性能的影响．实验表明，水热热压和纤维增强是改善混凝土一类脆性材料强韧性的有效手段     

亚麻纤维的碱-尿素化学改性研究

研究打成麻在碱-尿素改性处理时，纤维物理机械性能的变化．运用正交实验设计对改性参数优化，改变处理条件如浴比、温度、时间、碱用量、尿素用量等，得出最优的改性工艺方案．通过化学改性，使亚麻纤维在保持原有特性的基础上，纤维柔软度和弹性增加，并出现明显的卷曲，将有利于纺细号纱，提高亚麻产品的附加值．     

冷结晶对杨木纤维/聚乳酸复合材料性能的影响

采用杨木纤维与聚乳酸(PLA)粉末共混压制成一种新型生物质复合材料,以不同升温方式对纯PLA板材及其复合材料进行冷结晶,并通过示差扫描量热仪(DSC)、偏光显微镜(POM)、扫描电子显微镜(SEM)和万能力学试验机等对其进行测试和表征。结果表明:通过冷结晶方法,纯PLA板材和复合材料的结晶度分别由6%和18.3%提高到50%左右,两者的密度和冲击强度没有发生明显变化; 但是复合材料弯曲强度和模量分别下降了约30%和16%,纯PLA板的弯曲强度也有一定程度的下降。通过SEM对复合材料微观结构进行表征,发现力学强度的下降是由于结晶后的PLA基体与木纤维之间的界面相容性变差造成的。通过POM观察冷结晶过程,发现纯PLA板及其复合材料形成大量的微小晶体,导致两者的透明性下降,因此,调控晶体结晶度有望成为改变PLA材料透明性能的新方法。     

植物纤维与聚乳酸制备生物质复合材料的研究

本文研究了以植物纤维与聚乳酸为原料制备生物质复合材料的工艺,探讨不同加工方式、纤维种类和添加量对植物纤维/聚乳酸复合材料拉伸性能及透湿性的影响,并利用扫描电镜对复合材料进行表征。研究结果表明:复合材料采用熔融挤出加工方式比物理混合的性能好,而蔗渣纤维作为填料是较好的选择;同时,当植物纤维添加量低于20%时,随着添加量的增加,材料的拉伸强度和断裂伸长率随之下降。     

Study on the Structure and Properties of Polynosic Fiber Treated by Alkali

The regenerated cellulose fibers, made from wood pulp, have excellent physical properties like cotton fiber. Especially polynosic fibers can be mercerized by alkali, but conventional Viscose fiber can not be treated or mercerized by alkali. The paper studies on behavior of polynosic fibers treated by alkali, including physical properties, such as weight loss, tensile strength and elongation, and fiber structures properties. In this paper, on the basis of study on polynosic fibers treated by alkali, the conclusions were drawn as following. Firstly, polynosic fiber is good at alkali resistance. Secondly, the changes of fiber structure and physical properties begin declining at 5 wt% NaOH concentration and reverse changes take place at 10 wt%.