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.     

Surface modification of sisal fibers: Effects on the mechanical and thermal properties of their epoxy composites

The aim of this paper is to evaluate the mechanical and thermal properties of sisal fiber reinforced epoxy matrix composites as a function of modification of sisal fiber by using mercerization and silane treatments. The changes introduced by the treatments on the chemical structure of sisal fibers have been analyzed by infrared spectroscopy (FTIR). Thermal behavior of both sisal fibers and composites has been studied by thermogravimetric analysis (TGA). Both treatments clearly enhanced thermal performance and also mechanical properties of fibers, being other physical properties also modified. Mercerization, above all when combined with silanization, led to significant enhancement on mechanical properties of composites as a consequence of increasing mechanical properties of fibers and improving fiber/matrix adhesion. POLYM. COMPOS., 26:121–127, 2005. © 2005 Society of Plastics Engineers     

Crystallization kinetics by differential scanning calorimetry for PCL/starch and their reinforced sisal fiber composites

Calorimetric results obtained by differential scanning calorimetry (DSC) have been used to develop a kinetic model for the crystallization behavior of PCL/starch and their composites with sisal fibers. The model takes into account the effects of nucleation and crystal growth, and it is able to describe the isothermal and non‐isothermal conditions, especially for the low cooling rates. The effect of the sisal fiber has also been analyzed. The Avrami exponent was 2.0 for the crystallization of PCL/starch and sisal fiber reinforced composite. The activation energy of the crystallization process was 4.3 and 4.0 kJ/mol for PCL/starch and sisal composite, respectively. The induction time of the crystallization and the crystallization rate was not influenced by the presence of sisal fiber.     

热处理剑麻/PLA复合材料的制备与力学性能研究

采用真空干燥箱对剑麻纤维进行预处理,并与聚乳酸(PLA)复合制备了剑麻纤维含量为50%的全降解环保型复合材料。研究了真空条件下剑麻纤维热处理温度、热处理时间对剑麻纤维成分、结构和复合材料性能的影响,并通过红外光谱和扫描电镜分析其作用机理。结果表明:在真空条件下,热处理使剑麻结构发生变化,半纤维素降解,改善了界面结合能力,且适宜的热处理温度、热处理时间有利于复合材料力学性能的提高。     

不同预处理对剑麻纤维组分和结构的影响

采用机械破碎、酸法蒸煮、氢氧化钠溶液碱法蒸煮、氨水处理和蒸汽爆破等五种不同物理和化学方法对剑麻纤维进行处理。通过化学分析、扫描电镜(SEM)及红外光谱(IR)等手段表征了处理前后剑麻纤维组分和结构的变化。结果表明,不同预处理方法均使剑麻纤维组分分离,杂质含量降低,纤维素含量提高。其表面形态和聚集态结构根据不同的处理方法而发生不同变化。在五种方法中以碱煮和蒸汽爆破处理效果较佳。     

Sisal fibers treated with NaOH and benzophenonetetracarboxylic dianhydride as reinforcement of phenolic matrix

In this work, composites based on a phenolic matrix and untreated‐ and treated sisal fibers were prepared. The treated sisal fibers used were those reacted with NaOH 2% solution and esterified using benzophenonetetracarboxylic dianhydride (BTDA). These treated fibers were modified with the objective of improving the adhesion of the fiber–matrix interface, which in turn influences the properties of the composites. BTDA was chosen as the esterifying agent to take advantage of the possibility of introducing the polar and aromatic groups that are also present in the matrix structure into the surface of the fiber, which could then intensify the interactions occurring in the fiber–matrix interface. The fibers were then analyzed by SEM and FTIR to ascertain their chemical composition. The results showed that the fibers had been successfully modified. The composites (reinforced with 15%, w/w of 3.0 cm length sisal fiber randomly distributed) were characterized by SEM, impact strength, and water absorption capacity. In the tests conducted, the response of the composites was affected both by properties of the matrix and the fibers, besides the interfacial properties of the fiber–matrix. Overall, the results showed that the fiber treatment resulted in a composite that was less hygroscopic although with somewhat lower impact strength, when compared with the composite reinforced with untreated sisal fibers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

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。     

Development and physico‐mechanical behavior of LDPE–sisal prepreg‐based composites

Low‐density polyethylene (LDPE)‐coated sisal fiber prepreg was prepared by using solution coating process. These coated fiber prepregs were consolidated to make composites having different weight fraction of sisal fibers in a hot compression‐molding machine. This experimental study reveals that higher loading of sisal fiber up to 57wt% in LDPE–sisal composites is possible by this technique. Mechanical and abrasive wear characteristics of these composites were determined. The tensile strength of composites increased with the increase in sisal fiber concentration. Coating thickness of LDPE was varied by changing the viscosity of LDPE–xylene solution that manifested to different weight fraction of fiber in sisal–LDPE composites. Mechanical, dynamic mechanical, and abrasive wear characteristics of these composites were determined. The tensile strength and modulus of sisal composites reached to 17.4 and 265 MPa, respectively, as compared to 7.1 and 33MPa of LDPE. Storage modulus of sisal composites LD57 reached to 2.7 × 10⁹ MPa at 40°C as compared to 8.1 × 10⁸ MPa of LDPE. Abrasive wear properties of LDPE and its composites were determined under multi‐pass mode; pure LDPE showed minimum specific wear rate. The specific wear rate of composites decreased with the sliding distance. Increase of coated sisal fiber content increased the specific wear rate at all the sliding distances, which has been explained on the basis of worn surface microstructures observed by using SEM. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

剑麻纤维的改性方法对其形态结构和力学性能的影响

通过碱处理和烷基化处理改性剑麻纤维,研究剑麻纤维改性前后表面形态和力学性能的变化,并分析不同改性方法对加工过程中纤维断裂方式的影响.结果表明:碱处理和烷基化处理刻蚀了剑麻纤维表面;烷基化处理使纤维的断裂方式发生改变,导致纤维原纤化;剑麻纤维经改性处理后,拉伸强度分别提高9%和21%,断裂伸长率分别提高63.4%和122.2%.     

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。     

剑麻纤维增强聚丙烯复合材料的冲击特性研究

采用片状层压工艺制备了短切剑麻纤维(SF)／聚丙烯(PP)复合材料，用高级仪器化摆锤冲击试验机对复合材料的冲击过程进行了全面分析，并借助扫描电子显微镜对复合材料的冲击破坏断口进行观察。结果表明：当SF的长度为20mm、wpp=30％时，SF对PP的增韧效果最好。采用短切SF增强PP基体，可使复合材料断裂过程吸收的能量增加，裂纹扩展缓慢，断裂后期吸收能量增大。     

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。     

Tensile properties of short sisal fiber reinforced polystyrene composites

The tensile properties of polystyrene reinforced with short sisal fiber and benzoylated sisal fiber were studied. The influence of fiber length, fiber content, fiber orientation, and ben-zoylation of the fiber on the tensile properties of the composite were evaluated. The ben-zoylation of the fiber improves the adhesion of the fiber to the polystyrene matrix. the benzoylated fiber was analyzed by IR spectroscopy. Experimental results indicate a better compatibility between benzoylated fiber and polystyrene. the benzoylation of the sisal fiber was found to enhance the tensile properties of the resulting composite. The tensile properties of unidirectionally aligned composites show a gradual increase with fiber content and a leveling off beyond 20% fiber loading. The properties were found to be almost independent of fiber length although the ultimate tensile strength shows marginal improvement at 10 mm fiber length. The thermal properties of the composites were analyzed by differential scanning calorimetry. Scanning electron microscopy was used to investigate the fiber surface, fiber pullout, and fiber–matrix interface. Theoretical models have been used to fit the experimental mechanical data. © 1996 John Wiley & Sons, Inc.     

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。     

剑麻纤维增强混凝土力学性能研究

植物纤维作为一种可再生、价格低廉、来源广泛的资源,其在混凝土中的应用具有很好的前景.运用简单的力学实验,综合分析纤维的掺量、长径比对混凝土强度的影响,采用不同掺量的纤维,验证了剑麻纤维在增强混凝土抗压强度等基本力学性能方面的机理.结果表明:(1)剑麻纤维的加入会在一定程度上增强混凝土的抗压强度.(2)最佳掺量为2 kg/m3,与普通混凝土相比,剑麻纤维混凝土强度最大提升幅度为9％左右.     

剑麻/钢纤维增强改性酚醛树脂力学和摩擦性能

采用改性酚醛树脂为基体,剑麻/钢纤维混杂为增强纤维,通过辊炼、模压成型工艺制备了剑麻/钢纤维增强酚醛树脂复合材料.研究了剑麻纤维的加入及含量对聚砜改性酚醛树脂复合材料力学性能、摩擦磨损性能及热稳定性能的影响.结果表明:剑麻纤维质量分数为15%、钢纤维为10%时,复合材料的冲击和弯曲强度分别为3.82 kJ/m2和59.6 Mpa,达到最大;随着剑麻纤维含量的增加,复合材料的摩擦系数降低,热稳定性能下降,当剑麻纤维质量分数为10%时,复合材料的摩擦性能优异;复合材料的磨损面呈现黏着磨损和疲劳磨损特征.     

剑麻纤维增强聚氯乙烯复合材料工艺与性能的研究

本文通过对剑麻纤维和聚氯乙烯基体改性，并变化成型参数，来研究它们对形成的复合材料力学性能和耐水性的影响，从而制订出剑麻纤维／聚氯乙烯复事材料的最佳成型工艺。     

Crystalline transition behavior of sisal in cycle process

In this study, the effects of cycle process on crystalline transition behavior of sisal fiber were investigated in various conditions (in air, in composites and in argon) by XRD analysis. The results indicated that the sisal cellulose falls into cellulose I, and the polymorphic transformation didn't occur for sisal cellulose after cycle process. With increasing of thermal cycle times, the crystalline size of sisal became smaller gradually, but the change was not obvious when sisal fiber was treated thermally in air and in argon before five times. The change trend of crystalline index of sisal after cycle process in air and in argon was similar. However, it is different in composites. From once to 10 times cycle process, the crystalline index of sisal fiber was degressive. When the cycle times was close to 15, crystalline index increased gradually. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Effect of layering pattern on dynamic mechanical properties of randomly oriented short banana/sisal hybrid fiber–reinforced polyester composites

Dynamic mechanical test methods have been widely employed for investigating the structures and viscoelastic behavior of polymeric materials to determine their relevant stiffness and damping characteristics for various applications. Randomly oriented short banana/sisal hybrid fiber–reinforced polyester composites were prepared by keeping the volume ratio of banana and sisal 1 : 1 and the total fiber loading 0.40 volume fraction. Bilayer (banana/sisal), trilayer (banana/sisal/banana and sisal/banana/sisal), and intimate mix composites were prepared. The effect of layering pattern on storage modulus (E′), damping behavior (tan δ), and loss modulus (E″) was studied as a function of temperature and frequency. Bilayer composite showed high damping property while intimately mixed and banana/sisal/banana composites showed increased stiffness compared to the other pattern. The Arrhenius relationship has been used to calculate the activation energy of the glass transition of the composites. The activation energy of the intimately mixed composite was found to be the highest. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2168–2174, 2005     

Effect of interface modification on the mechanical properties of polystyrene‐sisal fiber composites

The effect of interface modification on the mechanical (tensile, impact and flexural) properties of polystyrene–sisal fiber composites was investigated. The interface modification was performed by treatment of sisal fibers with benzoyl chloride, polystyrene maleic anhydride (PSMA), toluene diisocyanate (TDI), methyl triethoxy silane and triethoxy octyl silane. These interface modifications improve the compatibility of hydrophilic sisal fiber with a hydrophobic polystyrene matrix and change the tensile, impact and flexural properties of the composite, but to varying degrees depending on the fiber modification. The treated fibers were analyzed by spectroscopic techniques. Scanning electron microscopy was used to investigate the fiber surface, fiber pullout, and fiber‐matrix interface.