聚乳酸/剑麻复合材料流变性能表征

利用转矩流变仪测量流变特性的方法,表征了不同剑麻纤维含量下,聚乳酸(PLA)/剑麻复合材料的流变性能,并测量实验后纤维的长度和宽度、PLA分子量,分析剑麻纤维含量和转速对复合材料体系中纤维长度的影响,以及PLA降解情况。结果表明,复合材料的非牛顿指数在纤维含量为10%左右出现峰值,并进一步随含量的增加而减小。复合体系中,刚性剑麻纤维受到来自于转子、聚合物和纤维之间的作用力,纤维被剪短,长径比减小;聚乳酸会受到转速和纤维含量的影响发生降解,这些因素都会影响PLA/剑麻复合材料的流变性能。     

剑麻纤维增强热塑性淀粉复合材料的制备及性能研究

为研究剑麻纤维增强的热塑性淀粉复合材料的制备工艺及热稳定性,以玉米淀粉为原料,先制得热塑性淀粉,再以剑麻纤维为骨架增强体制备剑麻纤维增强热塑性淀粉复合材料,通过正交试验优化制备工艺,DSC、TG/DTG、SEM分析其热稳定性及结构。正交试验表明,各因素对材料抗拉强度影响的主次顺序为纤维长度 >纤维用量 >模压成型温度 >填料用量;最佳工艺条件为纤维长度15mm、纤维用量35g、模压成型温度200℃、填料用量5g,此时材料的抗拉强度可达到4.45MPa。利用差示扫描量热分析和热重分析分别对热塑性淀粉及剑麻纤维复合材料的热稳定性进行了分析,结果表明,热塑处理提高了淀粉的熔融温度,有利于淀粉与纤维素羟基间的氢键结合,且热塑过程在一定程度上降低了淀粉的热稳定性;剑麻纤维复合材料的热降解过程主要发生在200~400℃温度区间。SEM分析显示最佳工艺条件下得到的复合材料具有较好的泡孔结构。     

聚乙交酯纤维的结构及其降解性能

纺制了聚乙交酯(PGA)纤维,并对其进行了不同温度和时间的热处理。对处理后PGA纤维的结构进行了测试,并将其放置于恒温箱的磷酸盐缓冲液中进行两周降解处理,研究了不同热处理工艺下PGA纤维的结构及降解性能。试验结果表明:随着热处理温度的提高,PGA纤维材料的晶区取向度变化不大,结晶度逐渐增大,晶粒尺寸也相应发生变化;在试验条件下,经过恒温缓冲液两周时间的降解处理,纤维的强度保持率随热处理温度提高呈现先增大后降低的趋势,纤维的强度保持率在110℃出现最大值;同时,在热处理温度110℃时,随着热处理时间的延长,PGA纤维的强度保持率增加。     

碱处理对剑麻纤维增强聚乳酸可降解复合材料性能的影响

以剑麻纤维(SF)和聚乳酸(PLA)为原料,通过注塑成型工艺制备了剑麻纤维增强聚乳酸可降解复合材料。研究了连续碱处理剑麻纤维(CASF)和未改性处理剑麻纤维(USF)在不同含量时对复合材料力学性能、吸水性及可降解性能的影响。结果表明:剑麻纤维的质量分数会显著影响复合材料的力学性能、吸水性和降解性能。相较于未改性处理剑麻纤维(USF),碱处理剑麻纤维(CASF)可以进一步提高复合材料的力学性能,降低复合材料的吸水率,延缓剑麻纤维增强可降解树脂基复合材料的降解速率,且酶降解法相较于土埋法降解能够显著加快复合材料的降解速率。当剑麻纤维含量为20%时,CASF/PLA复合材料的拉伸强度、弯曲强度和弯曲模量相较于纯PLA和USF/PLA分别提高了32.71%、10.08%;19.63%、12.11%;97.33%、12.40%;其冲击强度相较于纯PLA提高了71.19%。     

剑麻纤维增强聚乳酸复合材料酶降解研究

通过热压成型的方式制备了剑麻纤维增强聚乳酸（PLA/SF）复合材料,并通过K蛋白酶降解方式研究了该复合材料的生物降解性能,利用差热扫描量热仪测试分析了复合材料在酶降解过程中的非等温结晶性能。研究发现,剑麻纤维的加入加快了聚乳酸及其复合材料的降解速率,且随着剑麻纤维含量的增加,其降解速率提高;剑麻纤维的加入对聚乳酸的结晶性能有一定的影响,进而也影响了复合材料的酶水解速度。     

剑麻预处理对热塑性淀粉复合材料力学性能及降解性能的影响

采用碱、蒸汽爆破等对剑麻纤维进行预处理,考察了不同预处理方法对剑麻纤维增强热塑性淀粉力学性能及降解性能的影响。结果表明:碱处理能够提高复合材料的力学性能,延长材料降解周期,是制备剑麻纤维增强热塑性淀粉复合材料有效的预处理方法;剑麻纤维增强热塑性淀粉的机理是甘油在淀粉及剑麻纤维之间起到桥梁作用,提高了热塑性淀粉与剑麻纤维的界面结合力,从而提高了复合材料的力学性能。     

剑麻纤维的表面改性及其复合材料的研究进展

简述了剑麻纤维的组成、结构及力学性能,并总结了剑麻纤维表面改性的几种方法,包括物理方法：热处理、酸碱处理、有机溶剂处理;化学方法：改变表面张力、界面偶合、表面接枝聚合。同时论述了剑麻纤维的表面改性对复合材料力学性能的影响。     

剑麻纤维／酚醛树脂复合材料研究

本文采用碱处理、硅烷偶联剂处理、化学接枝和热处理等物理化学方法，对剑麻纤维进行改性。研究了改性后短剑麻纤维／酚醛树脂复合材料的弯曲性能、无缺口冲击强度和布氏硬度，借助扫描电子显微镜观察了复合材料的弯曲断口形貌，并研究了剑麻纤维的不同处理方法对复合材料耐水浸泡性的影响。结果表明：剑麻纤维经硅烷偶联剂处理后，能有效改善刚性的剑麻纤维与脆性的酚醛树脂基体之间的粘结，从而提高了复合材料的综合力学性能，剑麻     

三种天然纤维对PBS降解性能的影响

麦秸秆纤维、剑麻纤维和甘蔗皮纤维经碱处理后与聚丁二酸丁二醇酯(PBS)熔融共混制备复合材料,通过扫描电镜(SEM)对三种天然纤维进行表面分析,通过测试失重率、拉伸强度变化、断裂伸长率变化和热性能变化分析复合材料的降解性能。以纤维种类、填埋时间和纤维添加质量分数三个因素分析PBS在天然土壤填埋100天的降解行为。结果表明:碱处理效果和降解效果顺序为甘蔗皮纤维麦秸秆纤维剑麻纤维,甘蔗皮纤维添加质量分数为5%、填埋100天时复合材料的降解效果最佳。     

表面处理对剑麻纤维布/不饱和树脂材料性能影响

采用碱、高锰酸钾及热对剑麻纤维布进行了表面处理,并由真空辅助树脂传递模塑成型(VARTM)工艺制备了剑麻纤维布增强不饱和聚酯树脂复合材料。通过对复合材料的力学性能及吸水性的测试,研究了不同剑麻纤维布表面处理对其不饱和聚酯树脂复合材料性能的影响。结果表明:经过碱处理,复合材料的拉伸、弯曲,冲击强度提高最大,可分别提高26.5%,16.5%和22.6%,吸水率降低了47.5%。对剑麻纤维布进行表面处理可使复合材料的界面性能得到改善,力学性能提高,吸水性降低。     

剑麻/含红土聚乙烯基复合材料制备与性能

针对废旧地膜资源化利用过程中出现的高成本和低性能问题，本文提出了废旧地膜免清洗和剑麻纤维边角料增强的废旧地膜资源化利用技术。采用挤出造粒和注塑成型工艺，制备了剑麻边角料填充含红土废旧聚乙烯复合材料，分析了红土和剑麻纤维边角料对废旧地膜的填充作用。结果表明，红土颗粒使废旧地膜注塑试样的拉伸模量、硬度和耐热温度分别提高了34.4%、41.3%、和33.1%。红土颗粒难以和塑料基体形成良好的界面粘结，导致含红土废旧地膜注塑试样的拉伸强度、弯曲性能和冲击强度轻微降低，表明红土颗粒不能对废旧地膜进行增韧增强，但可以提高模量和耐热温度。剑麻纤维边角料对含红土废旧地膜具有明显的增强增韧作用，随着剑麻纤维添加量的增加，剑麻纤维填充的含红土废旧地膜复合材料的力学性能增加。剑麻纤维填充量超过一定值后，会在复合材料中引入气孔，同时会降低剑麻纤维的分散程度，出现剑麻聚集体，导致复合材料的力学性能降低。     

An investigation of sound absorption coefficient on sisal fiber poly lactic acid bio‐composites

In this research, the mechanical, acoustical, thermal, morphological, and infrared spectral properties of untreated, heat and alkaline‐treated sisal fiber‐reinforced poly‐lactic‐acid bio‐composites were analyzed. The bio‐composite samples were fabricated using a hot press molding machine. The properties mentioned above were evaluated and compared with heat‐treated and alkaline‐treated sisal fibers. Composites with heat‐treated sisal fibers were found to exhibit the best mechanical properties. Thermo‐gravimetric analysis (TGA) was conducted to study the thermal degradation of the bio‐composite samples. It was discovered that the PLA‐sisal composites with optimal heat‐treated at 160°C and alkaline‐treated fibers possess good thermal stability as compared with untreated fiber. The results indicated that the composites prepared with 30wt % of sisal had the highest sound absorption as compared with other composites. Evidence of the successful reaction of sodium hydroxide and heat treatment of the sisal fibers was provided by the infrared spectrum and implied by decreased bands at certain wavenumbers. Observations based on scanning electron microscopy of the fracture surface of the composites showed the effect of alkaline and heat treatment on the fiber surface and improved fiber‐matrix adhesion. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42470.     

A Comparative Study on the Mechanical Properties of Jute and Sisal Fiber Reinforced Polymer Composites

The aim of the present study is to investigate and compare the mechanical properties of raw jute and sisal fiber reinforced epoxy composites with sodium hydroxide treated jute and sisal fiber reinforced epoxy composites. This is followed by comparisons of the sodium hydroxide treated jute and sisal fiber reinforced composites. The jute and sisal fibers were treated with 20% sodium hydroxide for 2 h and then incorporated into the epoxy matrix by a molding technique to form the composites. Similar techniques have been adopted for the fabrication of raw jute and sisal fiber reinforced epoxy composites. The raw jute and sisal fiber reinforced epoxy composites and the sodium hydroxide treated jute and sisal fiber reinforced epoxy composites were characterized by FTIR. The mechanical properties (tensile and flexural strength), water absorption and morphological changes were investigated for the composite samples. It was found that the sodium hydroxide treated jute and sisal fiber reinforced epoxy composites exhibited better mechanical properties than the raw jute and raw sisal fiber reinforced composites. When comparing the sodium hydroxide treated jute and sisal fiber reinforced epoxy composites, the sodium hydroxide treated jute fiber reinforced composites exhibited better mechanical properties than the latter.     

剑麻柄处理方法对剑麻纤维／脲醛树脂复合材料的性能影响

采用碱处理、偶联剂处理、醋酸处理等方法，对剑麻柄进行处理，再与自行合成的脲醛树脂(UF)进行捏合、模压，制成剑麻纤维／脲醛树脂共混复合材料。研究了碱处理最佳工艺以及不同处理方法对复合材料的力学性能、耐磨性、耐水性、电性能和热性能的影响，并与木粉／UF复合材料的性能进行了对比。结果表明：剑麻柄的处理方法对复合材料的电性能、热性能和吸水性影响不大；采用乙酰化处理剑麻柄时，复合材料强度较高。耐磨性好，此时剑麻纤维／UF复合材料的各项性能接近木粉／UF复合材料的性能     

Mechanical and viscoelastic properties of short fiber reinforced natural rubber composites: effects of interfacial adhesion,fiber loading,and orientation

The effect of a two-component dry bonding system consisting of resorcinol and hexamethylene tetramine on the mechanical and viscoelastic properties of short sisal fiber reinforced natural rubber composites has been studied. The studies were conducted with chemically treated and untreated short sisal fibers. Treated fibers impart better mechanical properties to the composites. By mixing with short fibers, the dynamic storage modulus (E') of natural rubber composites was improved. The effects of fiber-matrix adhesion on the mechanical and viscoelastic properties of the composites were investigated. The storage moduli and mechanical loss increased continuously with an increase in fiber loading but decreased with an increase of temperature. The influence of the fiber orientation on the mechanical and viscoelastic properties is discussed.     

The influence of chemical surface modification on the performance of sisal‐polyester biocomposites

This article concerns the effectiveness of various types and degrees of surface modification of sisal fibers involving dewaxing, alkali treatment, bleaching cyanoethylation and viny1 grafting in enhancing the mechanical properties, such as tensile, flexural and impact strength, of sisal‐polyester biocomposites. The mechanical properties are optimum at a fiber loading of 30 wt%. Among all modifications, cyanoethylation and alkali treatment result in improved properties of the biocomposites. Cyanoethylated sisal‐polyester composite exhibited maximum tensile strength (84.29 MPa). The alkali treated sisal‐polyester composite exhibited best flexural (153.94 MPa) and impac strength (197.88 J/m), which are, respectively, 21.8% and 20.9% higher than the corresponding mechanical properties of the untreated sisal‐polyester composites. In the case of vinyl grafting, acrylonitrile (AN)‐grafted sisal‐polyester composites show better mechanical properties than methyl‐methacrylate (MMA)‐grafted sisal composites. Scanning electron microscopic studies were carried out to analyze the fiber‐matrix interaction in various surface‐modified sisal‐polyester composites.     

Influence of fiber treatment on the performance of sisal–polypropylene composites

This article concerns the effectiveness of MAPP as a coupling agent in sisal–polypropylene composites. The fiber loading, MAPP concentration, and fiber treatment time influenced the mechanical properties of the composites. It was observed that the composites prepared at 21 volume percent of fibers with 1% MAPP concentration exhibits optimum mechanical strength. SEM investigations confirmed that the increase in properties is caused by improved fiber‐matrix adhesion. The viscoelastic properties of the treated and untreated composites were also studied. From the storage modulus versus temperature plots, an increase in the magnitude of the peaks was observed with the addition of MAPP and fiber reinforcement, thus showing an improvement in stiffness of the treated composites. The damping properties of the composites, however, decreased with the addition of the fibers and MAPP. The thermal properties of the composites were analyzed through DSC and TGA measurements. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1336–1345, 2004     

Preparation and properties of PBS/sisal‐fiber composites

We report the preparation of polybutylene succinate (PBS)/sisal‐fiber (SF) composites. The effects of mixing temperature and of steam‐explosion pretreatment of SFs on the mechanical properties of the composites were investigated, and the mechanism of action was studied by infrared spectroscopy, scanning electron microscopy, and x‐ray photoelectron spectroscopy. The results indicate that as the mixing temperature increases, PBS flows better and can graft onto steam‐exploded sisal fiber (SESF), the interfacial bond property between SESF and PBS improves, and the mechanical properties of the composites improve. The mechanical properties of the composites are maximal for a mixing temperature of 200°C. The results also demonstrate that the cellulose content and the specific fiber surface area can be increased by steam‐explosion pretreatment, so that the mechanical properties of the composites can be improved. POLYM. ENG. SCI., 2011. © 2010 Society of Plastics Engineers