Influence of redmud particle hybridization in banana/sisal and sisal/glass composites

A novel hybrid composite is developed by adding redmud as the secondary reinforcing filler with banana/sisal and sisal/glass fiber reinforced polyester composites. The composites are prepared by the hand layup technique followed by compression molding. The tensile, flexural, and impact strength of the composites are investigated by varying the parameters such as particle size (4 and 13?µm) and weight percentage (2, 4, 6, and 8?wt%) of redmud particle addition. The experimental result shows that the addition of redmud enhances the mechanical property of the hybrid composite. The maximum increase of 33% in tensile strength and 54% in flexural strength is observed for the sisal/glass composite and 25% increase in impact strength for the banana/sisal composite. The linear regression analysis is also introduced to predict the errors in the scatter plot. Furthermore, the Scanning Electron Microscopy (SEM) is used to study the effect of redmud on the interfacial bonding in the banana/sisal and sisal/glass fiber reinforced polyester composites.     

Study on the mechanical properties and thermal properties of jute and banana fiber reinforced epoxy hybrid composites

The aim of the present study is to investigate and compare the mechanical and thermal properties of raw jute and banana fiber reinforced epoxy hybrid composites. To improve the mechanical properties, jute fiber was hybridized with banana fiber. The jute and banana fibers were prepared with various weight ratios (100/0, 75/25, 50/50, 25/75 and 0/100) and then incorporated into the epoxy matrix by moulding technique to form composites. The tensile, flexural, impact, thermal and water absorption tests were carried out using hybrid composite samples. This study shows that addition of banana fiber in jute/epoxy composites of up to 50% by weight results in increasing the mechanical and thermal properties and decreasing the moisture absorption property. Morphological analysis was carried out to observe fracture behavior and fiber pull-out of the samples using scanning electron microscope.     

玻璃纤维立体织物增强环氧树脂泡沫夹层复合材料的制备及力学性能

为了进一步提高泡沫夹层复合材料的承载能力和综合性能,实现其在轨道交通及汽车等工业领域的应用,开展了玻璃纤维立体织物增强环氧树脂泡沫(GF-Fabric/EP)复合材料的制备及其力学性能的研究。制备GF-Fabric/EP复合材料及其夹层结构,探索了GF-Fabric/EP复合材料及其夹层结构的失效行为,以揭示立体织物的增强机制。结果表明：立体织物的引入可显著改善GF-Fabric/EP复合材料的强度、刚度及破坏应变;但在不同承载条件下,各纱线发挥承载作用和效果不同。面板、芯材各自的性能、尺寸及面/芯界面性能均是影响GF-Fabric/EP夹层复合材料力学性能及失效特征的重要因素。以三点加载下的弯曲性能为例,针对不同的GF-Fabric/EP夹层复合材料,需调整跨厚比和试样尺寸并获得理想的失效特征,方可对其弯曲性能或层间剪切性能进行有效、合理的评价。     

Effects of fiber surface treatments on mechanical properties of epoxy composites reinforced with glass fabric

In this study, effects of fiber surface treatments on mechanical behavior and fracture mechanism of glass fiber/epoxy composites were investigated experimentally. To change the composition of the glass and regenerate to the hydroxyl groups, activation pretreatment of heat cleaned woven glass fabric was performed using (v/v) HCl aqueous solution at different concentrations before silane treatment. The treatment of silanization of heat cleaned and acid activated glass fibers with γ-glycidoxypropyltrimethoxysilane were performed. In this work, short beam shear test has been conducted to determine the performance of the acid treatment and the silane treatment in terms of the interlaminar shear strength. The silane coating on the heat cleaned glass fibers increased the interlaminar shear strength of the composite. However, the silane coating on the acid activated glass fibers did not improve the interlaminar shear strength of the composite. In addition, the strengths of the glass fabric specimens in tension and flexure were investigated. When the glass fibers are first treated with HCl solution and then with silane coupling agent, the tensile strengths of the composites decreased significantly. Scanning electron photomicrographs of fractured surfaces of composites were performed to explain the failure mechanisms in the composite laminates broken in tension.     

Effect of glass fiber hybridization on properties of sisal fiber–polypropylene composites

Natural fiber reinforced polymer composites became more attractive due to their light weight, high specific strength, and environmental concern. However, some limitations such as low modulus, poor moisture resistance were reported. This study aimed to investigate the effect of glass fiber hybridization on the physical properties of sisal–polypropylene composites. Polypropylene grafted with maleic anhydride (PP-g-MA) was used as a compatibilizer to enhance the compatibility between the fibers and polypropylene. Incorporating glass fiber into the sisal–polypropylene composites enhanced tensile, flexural, and impact strength without having significant effect on tensile and flexural moduli. In addition, adding glass fiber improved thermal properties and water resistance of the composites.     

E玻璃纤维增强环氧树脂基复合材料轴向拉伸力学性能的应变率效应

采用MTS-810材料试验机、Zwick-HTM5020高速拉伸试验机及分离式Hopkinson拉杆（SHTB）实验装置,并结合数字图像相关性（Digital image correlation,DIC）分析方法,对E玻璃纤维增强环氧树脂基复合材料棒材在10^-3~2 400 s^-1应变率范围内的轴向拉伸力学性能进行了较系统的实验研究,获得了不同应变率下材料的应力-应变曲线,揭示了应变率对材料的拉伸强度和断裂应变的影响规律。通过显微分析拉伸试样的断口形貌,揭示了试样的断裂机制及对应变率的依赖性。实验结果表明：E玻璃纤维增强环氧树脂基复合材料的力学性能具有强烈的应变率效应,归一化拉伸强度随着应变率对数线性增加,而归一化断裂应变则随着对数应变率线性减小;断口显微分析显示：E玻璃纤维增强环氧树脂基复合材料的轴向拉伸断裂模式依赖于应变率,低应变率加载下试样发生沿45°方向的剪切断裂,随着应变率增大,试样断裂模式逐渐过渡到沿轴向的拉伸断裂,特别是在高应变加载下,观察到大量的玻璃纤维丝被拉断,同时环氧树脂基体也发生严重的碎裂现象,这反映了基体材料与玻璃纤维之间相互约束作用在增强。     

Investigating the mechanical properties of sisal/coconut palm hybrid fiber reinforced epoxy composite

In this study, a facile hybridization of sisal/coconut palm reinforced epoxy composite, is presented. The fabrication method involved the use of hand lay-up techniques. The results of the fabricated composites were investigated by using the universal testing machine, hardness testing machine, scanning electron microscope, and an impact testing machine. In order to obtain optimize results for the tensile, flexural, and impact strengths of the fabricated samples, the fabrication procedures involved varying the volume fractions of sisal and coconut palm hybrid with different compositions. The maximum tensile, flexural, and impact strengths measured for the fabricated fiber/polymer composite, are: 45 MPa, 90 MPa, and 38.9 kJ/m². The scanning electron microscopy (SEM) and energy dispersive x-ray spectrometry (EDS) of the composites showed that the composites with equal volume fractions of sisal and coconut palm fiber exhibited better performance and better mechanical properties. Furthermore, the improved mechanical properties such as hardness, tensile strength, flexural strength and impact strength were obtained with fibers of longer length. By considering the excellent mechanical properties of the fabricated composite, it is envisaged that the composite be suitable for the manufacturing of helmet, automobile and train coach interiors.     

Numerical and experimental analysis on tensile properties of banana and glass fibers reinforced epoxy composites

Sādhanā - In present day scenario, moving towards an environment friendly material is a key issue for manufacturing industries in order to provide suitable alternatives for the existing...     

Influence of nanosize clay platelets on the mechanical properties of glass fiber reinforced polyester composites

Glass fiber reinforced polyester composite and hybrid nanoclay-fiber reinforced composites were prepared by hand lay-up process. The mechanical behavior of these materials and the changes as a result of the incorporation of both nanosize clay and glass fibers were investigated. Composites were prepared with a glass fibre content of 25 vol%. The proportion of the nanosize clay platelets was varied from 0.5 to 2.5 vol%. Hybrid clay-fiber reinforced polyester composite posses better tensile, flexural, impact, and barrier properties. Hybrid clay-fiber reinforced polyester composites also posses better shear strength, storage modulus, and glass transition temperature. The optimum properties were found to be with the hybrid laminates containing 1.5 vol% nanosize clay.     

Dynamic mechanical properties of short sisal fibre reinforced polypropylene composites

The dynamic mechanical properties of short sisal fibre reinforced polypropylene composites containing both untreated and treated fibres have been studied with reference to fibre loading, fibre length, chemical treatments, frequency and temperature. By the incorporation of short sisal fibre into polypropylene, the storage moduli (E′)and loss moduli (E″) have been found to be increasing whereas the mechanical loss factor (tan δ) decreasing. The storage modulus decreases with increase in temperature. The treated fibre composites show better properties compared to untreated system. The Arrhenius relationship has been used to calculate the activation energy for the glass transition. The use and limitations of various theoretical equations to predict the tan δ and storage modulus of the fibre reinforced plastic composites have been discussed. Cole–Cole analysis has been carried out to understand the phase behaviour of the composite samples. A master curve for the modulus of the blend is drawn by applying the time–temperature super position principle.     

Effect of fiber surface texture on the mechanical properties of glass fiber reinforced epoxy composite

The effect of fiber sizing and surface texture on the strength and energy absorbing capacity of fiber reinforced composites has been evaluated at two length scales using the macromechanical quasi-static punch shear test and the micromechanical microdroplet test methods. E-Glass/SC-79 epoxy composite laminates with four different fiber sizing formulations with various degrees of chemical bonding and surface texture have been investigated. The failure modes during perforation and different energy dissipating damage mechanisms were identified and quantified. The punch shear strength and the total energy absorption per unit volume of composite with hybrid sizing have increased by 48% and 100% over the incompatible sizing. These results showed linear correlations with the interphase properties reported earlier by the authors (Gao et al., 2011) and provided a methodology for developing new sizing by tailoring chemical bonding and the fiber surface texture at the fiber–matrix interphase for improving both strength and energy absorption of composites.     

Mechanical property evaluation of sisal–jute–glass fiber reinforced polyester composites

The composite materials are replacing the traditional materials, because of its superior properties such as high tensile strength, low thermal expansion, high strength to weight ratio. The developments of new materials are on the anvil and are growing day by day. Natural fiber composites such as sisal and jute polymer composites became more attractive due to their high specific strength, lightweight and biodegradability. Mixing of natural fiber with Glass-Fiber Reinforced Polymers (GFRPs) are finding increased applications. In this study, sisal–jute–glass fiber reinforced polyester composites is developed and their mechanical properties such as tensile strength, flexural strength and impact strength are evaluated. The interfacial properties, internal cracks and internal structure of the fractured surfaces are evaluated by using Scanning Electron Microscope (SEM). The results indicated that the incorporation of sisal–jute fiber with GFRP can improve the properties and used as a alternate material for glass fiber reinforced polymer composites.     

Mercerization of sisal fibers: Effect of tension on mechanical properties of sisal fiber and fiber-reinforced composites

Sisal fibers were mercerized, under tension and no tension, to improve their tensile properties and interfacial adhesion with soy protein resin. Mercerization of fibers under tension is known to minimize fiber shrinkage and to lower the microfibrillar angle by aligning them along the fiber axis. Mercerization improved the fracture stress and Young’s modulus of the sisal fibers while their fracture strain and toughness decreased. Mercerized sisal fiber-reinforced composites with soy protein resin showed improvement in both fracture stress and stiffness by 12.2% and 36.2%, respectively, compared to the unmercerized fiber-reinforced composites. Scanning electron microscope (SEM) photomicrographs of the composite fracture surfaces showed shorter fibrils protruding in the mercerized fiber-reinforced composites resulting in better sisal fiber/soy adhesion. Changed fiber surface properties were also responsible for better adhesion.     

Pristine and amino functionalized carbon nanotubes reinforced glass fiber epoxy composites

Multi-phase composites have been studied by incorporating carbon nanotubes (CNTs) as a secondary reinforcement in an epoxy matrix which was then reinforced with glass fiber mat. Different types of CNTs e.g. amino functionalized carbon nanotubes (ACNT) and pristine carbon nanotubes (PCNT) were homogeneously dispersed in the epoxy matrix and two-ply laminates were fabricated using vacuum-assisted resin infusion molding technique. The issues related to CNT dispersion and interfacial bonding and its affect on the mechanical properties have been studied. An important finding of this study is that PCNT scores over ACNT in composites prepared under certain conditions. This is a very significant finding since PCNT is available at a much lower cost than ACNT.     

激光改性纤维对其增强环氧树脂复合材料力学性能的影响

利用激光对玻璃纤维、玄武岩纤维和碳纤维进行表面改性后,以环氧树脂为基体,分别制备三种纤维增强环氧树脂复合材料。利用SEM和万能试验机对表面改性前后的碳纤维形态、力学性能及三种纤维/环氧树脂复合材料的力学性能和断面形貌进行表征,研究了纤维激光表面改性对三种纤维及其增强环氧树脂复合材料力学性能的影响。结果表明:激光表面改性对碳纤维/环氧树脂复合材料的力学性能提升最高,其拉伸强度最大提高了77.06%,冲击强度最大提高了31.25%,玄武岩纤维/环氧树脂复合材料的力学性能提升次之,而玻璃纤维/环氧树脂复合材料的力学性能有所下降。因此,激光进行表面改性适用于碳纤维和玄武岩纤维。     

Three-body abrasive wear behaviour of carbon and glass fiber reinforced epoxy composites

Three-body abrasive wear behaviour of carbon–epoxy (C–E) and glass–epoxy (G–E) composites has been investigated. The effect of abrading distance, viz., 270, 540, 810 and 1080 m and different loads of 22 and 32 N at 200 rpm have been studied. The wear volume loss and specific wear rate as a function of load and abrading distance were determined. The wear volume loss increases with increasing load/abrading distance. However, the specific wear rate decreases with increase in abrading distance and increases with the load. However, C–E composite showed better abrasion wear resistance compared to G–E composite. The worn surface features have been examined using scanning electron microscope (SEM). SEM micrographs of abraded composite specimens revealed the high percentage of broken glass fiber compared to carbon fiber and also better interfacial adhesion between epoxy and carbon fiber.     

超低温介质对碳纤维增强树脂基复合材料力学性能的影响

针对超低温介质液氮和液氧对碳纤维增强树脂基复合材料(CFs/EP)力学性能的影响进行研究,将T700碳纤维和CFs/EP在液氮和液氧中处理120h,采用X射线光电子能谱(XPS)和SEM分析碳纤维表面元素和表面形貌的变化;并研究液氧和液氮处理后碳纤维和复合材料试样的力学性能。结果表明,在经液氮处理后的碳纤维表面,上浆剂有明显损伤产生,而经液氧处理后的碳纤维表面则没有损伤出现;两种超低温介质处理对碳纤维单丝拉伸强度、表面元素及其含量的影响几乎没有区别;经液氮和液氧超低温介质处理后,CFs/EP拉伸强度均有所下降,且两者下降率接近,分别约为15.26%和14.38%;弯曲强度均有大幅提高,且提高率接近,分别约为56.18%和57.81%。因此,液氧和液氮处理对CFs/EP力学性能的影响基本没有区别。     

Influence of polarity parameters on the mechanical properties of composites from polypropylene fiber and short banana fiber

Polypropylene (PP)/banana fiber (BF) composites were prepared from PP fiber and short banana fiber. BF surfaces were modified chemically to bring about improved interfacial interaction. The polarity parameters of the chemically modified BF were investigated using the solvatochromic technique. The empirical Kamlet–Taft solvatochromic polarity parameters such as hydrogen bond donating ability HBD or acidity (α), hydrogen bond accepting ability HBA or basicity (β), the dipolarity (π^*), Gutman acceptor number (AN), Reichardts E_T (30) values for the chemically modified BF was determined. It was found that the polarity of the BF was decreased after the chemical treatment. The fiber/matrix interactions were found to depend on the polarity of the BF. The improved fiber/matrix interaction was evident from the enhanced tensile and flexural properties. The lower impact properties of the treated fiber composites further point to the improved fiber/matrix interaction. The diameter of the chemically modified BF was measured using an optical microscope. Scanning electron microscopy studies revealed the changes of the surface morphology of the fibers after the chemical treatments.     

玻璃纤维复合材料孔隙率对超声衰减系数及力学性能的影响

在0.1~0.6 MPa热压压力条件下, 制备了不同孔隙率含量的玻璃纤维布/618环氧树脂层压板试件。采用超声C扫描及烧蚀密度法测定了试件的超声衰减系数与平均孔隙率, 并通过金相显微分析对孔隙的分布、 形状及尺寸进行了表征。讨论了孔隙率对层压板拉伸、 弯曲和层间剪切性能及超声衰减系数的影响规律, 获得了使力学性能下降的临界孔隙率及衰减系数值。结果表明, 随着固化压力减小, 孔隙率从0.976%增加到5.268%, 抗拉强度、 弯曲强度和层间剪切强度均下降, 衰减系数由1.460 dB·mm^-1增加到2.150 dB·mm^-1, 使力学性能下降的临界衰减系数约为1.5 dB·mm^-1。     

Mechanical and water absorption behaviour of banana/sisal reinforced hybrid composites

The tensile, flexural, impact and water absorption tests were carried out using banana/epoxy composite material. Initially, optimum fiber length and weight percentage were determined. To improve the mechanical properties, banana fiber was hybridised with sisal fiber. This study showed that addition of sisal fiber in banana/epoxy composites of up to 50% by weight results in increasing the mechanical properties and decreasing the moisture absorption property. Morphological analysis was carried out to observe fracture behaviour and fiber pull-out of the samples using scanning electron microscope.