Studies on Mechanical and Morphological Characterization of Developed Jute/Hemp/Flax Reinforced Hybrid Composites for Structural Applications

In the present study, an attempt has been made to develop and characterize natural fiber-based composites (jute/epoxy, hemp/epoxy, flax/epoxy) and their hybrid composites (jute/hemp/epoxy, hemp/flax/epoxy, and jute/hemp/flax/epoxy) using hand-lay-up technique. Mechanical characterization (tensile, flexural, impact, and hardness test) of the developed composites was performed. The interface between fiber and matrix was examined using scan electron microscopy (SEM). Among (jute/epoxy, hemp/epoxy, flax/epoxy), flax/epoxy composite has shown higher hardness (98 Shore-D) and tensile strength (46.2 MPa) whereas better flexural and impact strength have been shown by hemp/epoxy (85.59 MPa) and jute/epoxy (7.68 kJ/m²) composites respectively. Results showed that hybrid composites observed better mechanical properties. Jute/hemp/flax/epoxy hybrid composite showed the highest tensile strength, modulus and impact strength of 58.59 MPa, 1.88 GPa, and 10.19, kJ/m², respectively. Jute/hemp/epoxy hybrid composite achieved the maximum flexural strength of 86.6 MPa.     

Kenaf fibre-reinforced polyester composites: flexural characterization and statistical analysis

This paper deals with the effect of the chemical treatment, fibre ratio and fibre reinforcement structure on the flexural properties of kenaf-polyester composites. Composites were made from an unsaturated polyester matrix reinforced with an alkali-treated and virgin kenaf fibres in a loose fibres and nonwovens. Results reveal that alkali treatment improves the flexural properties of composites expect elongation. The same result was obtained when using a nonwoven structure us reinforcement. The best flexural properties were observed for 11.1% fibre weight ratio with the nonwoven structure reinforce composite. The flexural strength and the flexural modulus were 69.5 MPa and 7.11 GPa, respectively, for this composite while it was 42.24 MPa and 3.61, respectively, for polyester samples (no fibre reinforcement). A statistical study was carried out in order to study the effect of the alkali treatment, reinforcement structure and the reinforcement weight ration on the composite properties. This study proved that the parameter with most impact on the measured properties is the fibre-to-matrix weight ratio. And also this study aims to determine the optimum parameters allowing maximising all measured properties and we found that when using a nonwoven structure made with chemically-treated fibre at 11.10% fibre weight ratio, is the optimum solution.     

THE FASHION CONSUMER IN THE GLOBAL MARKETPLACE

Abstract

This monograph traces the various means by which flax fibre is transformed into linen yarns and fabrics. The principal innovations and developments of the past fifty years are identified. An extensive range of relevant literature is reviewed. Details are given of how the fibre is extracted from the stem of the flax plant and of the stages of yarn and fabric production. An explanation is given of how yarns are produced from short fibres (known as tow) using carding, drafting and dry spinning, and from long fibres (known as line) using hackling, drafting, doubling, roving and wet spinning in warm water. Further areas covered include yarn winding, linen weaving, dyeing and finishing. New applications for flax fibre, beyond traditional uses in apparel or furnishing fabrics, are also identified.     

Innovation in Linen Manufacture

This monograph traces the various means by which flax fibre is transformed into linen yarns and fabrics. The principal innovations and developments of the past fifty years are identified. An extensive range of relevant literature is reviewed. Details are given of how the fibre is extracted from the stem of the flax plant and of the stages of yarn and fabric production. An explanation is given of how yarns are produced from short fibres (known as tow) using carding, drafting and dry spinning, and from long fibres (known as line) using hackling, drafting, doubling, roving and wet spinning in warm water. Further areas covered include yarn winding, linen weaving, dyeing and finishing. New applications for flax fibre, beyond traditional uses in apparel or furnishing fabrics, are also identified.     

Influences of moisture absorption and chemical treatments on the resin flow characteristics of natural fibre nonwoven mats

A major challenge for the use of natural fibres in polymeric composites is their incompatibility with commonly used matrices, causing weak interfaces of the final composites. Many surface treatments to natural fibres have been proposed to eliminate or reduce these problems. In this paper, we evaluate the influences of three commonly used natural fibre chemical treatments on the resin flow characteristics of flax fibre nonwoven mats in a vacuum-assisted resin transfer moulding process. The alkalization treatment significantly increases the in-plane permeability and flow anisotropy of the natural nonwoven mat due to changes in fibre diameter, fibre surface tension and mat structure. The effects of silane and acetylation treatments on resin flow are much smaller. It is well known that in comparison with glass fibre, natural fibres can absorb a large amount of moisture from surrounding air. The absorption of moisture causes a considerable reduction in the in-plane permeability of natural fibre nonwoven mats.     

18—THE ABRASION-RESISTANCE OF SOME WOVEN FABRICS AS DETERMINED BY THE ACCELEROTOR ABRASION TESTER

The use of an Accelerotor abrasion tester is discussed, and the abrasion-resistance of several plain-weave fabrics is shown to depend on the type of fibre. The materials are ranked in order of decreasing resistance to abrasion with carborundum, rubber, metal, and plastics abradants. Polyamide fibres have outstanding resistance and cellulose-ester and regenerated protein fibres poor resistance to abrasion. The order of resistance of other synthetic-polymer fibres, regenerated cellulosic fibres, and natural fibres is shown to alter slightly according to the nature of the abradant, the linear density of the fibre, and the sett of the fabric. The results are in general agreement with published data, but the resistance of polypropylene-fibre fabrics is lower than it was expected to be.

Microscopical examination of detritus confirmed that this consisted of small segments of complete fibre, which indicated that abrasion occurs by fibre breakage. A useful correlation is established between the specific strength and initial modulus of a fibre, or the energy of rupture of mechanically conditioned fibres, and the abrasion-resistance of a fabric.     

Lengthwise jute fibre properties variation and its effect on jute–polyester composite

In this study, the jute reeds were equally divided lengthwise from root to tip in three portions namely root, middle and tip. The fibre diameter, fineness, tensile strength and bundle strength of the three portion jute were evaluated and compared. Unidirectional composites containing about 35(wt/wt)% jute fibre by weight were produced in unsaturated polyester resin matrix. The effect of fibre property variation in composite’s mechanical properties was studied. Tensile and flexural properties of composites made from three portions of jute reed were studied. It was observed that tensile and flexural strength of root portion based composites are 44% and 35% higher than tip portion based composites. Tensile and flexural modulus of tip portion based composites is 18% and 17% higher than root portion based composites.     

The effect of hydrophilic (polyvinyl alcohol) fiber content on the flexural behavior of engineered cementitious composites (ECC)

This paper investigates the effect of hydrophilic polyvinyl alcohol (PVA) fiber’s content (1.2–2.0% volume of composite) on the flexural behavior of engineered cementitious composites (ECC) materials. Different parameters of flexural behavior such as strength at first-cracking and post-cracking stages, deflection at ultimate load, toughness indices according to ASTM 1018, flexural modulus, and energy absorption were determined. Test results showed that the flexural strength and flexural modulus of composites significantly increases by increment in fiber content. However, flexural strength of composites varies from 8.5 to 14 MPa depending on amount of PVA fibers. The toughness indices, deflection at max load and energy absorption were decreased by further increase in the fiber content from 1.6 to 2%. It was indicated that there was an indirect relationship between flexural strength and ductility of composite in higher amount of fiber content.     

Composites from Bast Fibres-Prospects and Potential in the Changing Market Environment

Abstract

Composite materials reinforced with natural fibres, such as flax, hemp, kenaf and jute, are gaining increasing importance in automotive, aerospace, packaging and other industrial applications due to their lighter weight, competitive specific strength and stiffness, improved energy recovery, carbon dioxide sequestration, ease and flexibility of manufacturing and environmental friendliness besides the benefit of the renewable resources of bast fibres. The market scenario for composite applications is changing due to the introduction of newer biodegradable polymers, such as PLA synthesized from corn, development of composite making techniques and new stringent environmental laws requiring improved recyclability or biodegradability for industrial applications where stress bearing capacities and micro-mechanical failures dictate serviceability. Bast fibre reinforced composites, made from biodegradable polymers, will have to compete with conventional composites in terms of their mechanical behaviour. Biocomposites, in which natural fibres, such as kenaf, jute, flax, hemp, sisal, corn stalk, bagasse or even grass are embedded in a biodegradable matrix, made as bioplastics from soybean, corn and sugar, have openedup new possibilities for applications in automotive and building products. Obviously, new approaches to research and development will be required to improve their mechanical properties, such as tensile, bending and impact resistance to match their performance and commercial competitiveness against petroleum based products. The research community has to look at the various possibilities of combining natural fibres, such as sisal, flax, hemp and jute with polymer matrices from non-renewable and renewable resources to develop cost effective biocomposites. This paper will review the newer products and techniques that can improve the properties of bast fibre based composites as well as potential structural and non-structural applications which can increase their market share.     

Effect of relative humidity on some physical and mechanical properties of different types of fibreboard

Equilibrium moisture content and strength properties as a function of relative humidity (RH) were measured in three types of commercial fibreboards with different densities. The measurements were made after specimens had been conditioned to equilibrium at 35, 50, 65, 80 and 95% RH and 20 °C. It was shown that the modulus of elasticity decreased slightly between 35 and 65% RH and markedly – at above 65% RH for all types of boards. A very strong decrease of modulus of elasticity was observed at about 80% RH (capillary condensation). A similar decreasing trend was observed in bending strength. Overall, high RH had a noticeably detrimental effect both on the MOE and the bending strength for all tested boards. Adequate correlation exists between bending MOE and bending strength with moisture content. The lower the density of boards the higher their equilibrium moisture content.     

Evaluation of physico-mechanical characteristics of cashew nut shell liquid-epoxy composites with Borassus and Tamarind fruit fibres as reinforcements

In this study, Cashew Nut Shell Liquid (CNSL)-epoxy matrix-based composites reinforced with borassus and tamarind fibres were fabricated using compression moulding technique. Three different types of composites were fabricated, namely Borassus fruit fine fibre/CNSL-epoxy composites (BF composites), Tamarind fibre/CNSL-epoxy composites (TF composites) and Tamarind/Borassus fruit fine fibre CNSL-epoxy hybrid composites (HB composites). In addition, CNSL-epoxy neat polymer was also fabricated for comparison. Physical properties such as micro-hardness, void percentage, and mechanical properties like tensile, flexural, Interlaminar Shear Strength (ILSS), and impact strength were investigated. Scanning Electron Microscope (SEM) was used to study the failure mechanism of the composites. Experimental results indicate that tensile and flexural properties of BF composites were higher when compared to TF and HB composites. Micro-hardness and impact strength of HB composites were better than the others. SEM images indicated better fibre-matrix bonding in BF composites indicating improved resistance to delamination. Thus, borassus and tamarind fibre reinforced CNSL-epoxy composites can be used as an alternative material for light to moderately loaded structural engineering applications.     

竹原/亚麻复合材料力学性能的模糊评判

采用竹原纤维、亚麻纤维作为增强体,低熔点聚酯纤维(LMPET)及丙纶纤维(PP)做基体,通过非织造工艺制作混合纤维预成型件,采用模压成型工艺制作植物纤维增强复合材料。用模糊综合评判的方法,探讨增强相与基体相选用的纤维种类及纤维质量百分率对材料力学性能的影响。利用扫描电镜研究了复合材料拉伸断口的形貌。结果表明:LMPET/40%竹原纤维复合材料的力学性能最优,纵、横向拉伸强度分别为136.00 MPa和87.58 MPa;纵、横向弯曲强度分别为534.00 MPa和470.00 MPa,超过了普通工程塑料的水平。     

Polyvinyl Chloride Reinforced with Areca Sheath Fiber Composites—An Experimental Study

ABSTRACT

This research work deals with fibrous composites obtained by using treated and untreated areca sheath (AS) fibers reinforced in polyvinyl chloride (PVC) by injection molding process. Surface treatments of fibers have been carried out to have a better compatibility with PVC matrix. The tensile and flexural strength have been found to increase at the early stage with the increase in treated areca fiber content till optimum (18 wt% of fiber) fiber loading thereafter declines. At optimum fiber loading, the tensile strength, flexural strength and young’s modulus values are 42.38 MPa, 18.22 MPa and 2.38 GPa, respectively, which give maximum values in comparison to other fiber loadings. Thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), biodegradability tests and scanning electron microscopy (SEM) have been used for analysis. The TGA inferred that the thermal stability of the composites increased as compared to neat PVC matrix. Further, the composites exhibit excellent biodegradability property and their biodegradability increases with the increase of areca fiber content. From the properties obtained at optimum fiber loading (18 wt% of fiber), the composite can be suitable for automotive dashboard and door panel applications.     

Evaluation of the Influence of Fibre Length and Concentration on Mechanical Performance of Hemp Fibre Reinforced Polypropylene Composite

Abstract

The paper deals widi die evaluation of interfacial shear stress (ISS) between reinforcement fibre (hemp) and polypropylene matrix through single fibre pull-out method and subsequently the critical length of the composite grade hemp fibre has been determined. In the present study the average ISS value of 5.9 MPa was used to determine the critical length of hemp fibre, which was found to be 3.4 mm. The theoretical prediction of the tensilestrength and modulus of hemp-polypropylene composite by using Kelly-Tyson and Cox-Krenchel models, respectively, have been reported in the paper. Model results were validated by experimental works with different fibre lengths and volume fraction of hemp fibre in the composite. The effect of fibre length and content on the flexural strength and stiffness of the hemp-polypropylene composite has also been studied. The effect of moisture absorption on composite tensile strength was predicted by modifying the Kelly-Tyson model. The model curve was also compared with another set of experimental works done at differentmoisture contents in the composite.     

体积含量对织物/水泥复合材料弯曲性能的影响

采用无碱玻璃纤维机织物,制备了不同体积含量的织物增强水泥基复合材料,通过三点弯曲抗折强度试验和断裂面形貌数码照片分析,研究了织物体积含量对机织物增强水泥基复合材料弯曲性能的影响。研究结果表明,玻璃纤维机织物体积含量从1%上升到5%时,织物增强水泥复合材料全载荷挠度曲线的形状和弹性模量没有明显变化,经向抗折强度从8.5 MPa上升到17.8 MPa,纬向抗折强度从8.1 MPa上升到17.2 MPa,但增加的幅度与聚合物基单向复合材料纵向强度的混合定律不相符,断裂能从0.53 kJ/m2上升到1.89 kJ/m2,且增加的幅度明显增大。     

The Tensile and Flexural Properties of Textile Composites

The mechanical properties of thermoset (glass-fibre-reinforced epoxy, polyester, and vinylester) and thermoplastic (glass-fibre-reinforced poly(ethylene terephthalate)) composite laminates manufactured from novel textile fabrics are investigated. The tensile and flexural properties of warp-knitted and woven composites were determined for glass-fibre-reinforced epoxy, polyester, and vinylester. The tensile strength and modulus were slightly lower than expected, mainly owing to fibre misalignment. The flexural failures of the thermoplastic laminates initiated on the compression face, and they were stable and gradual, i.e. a large amount of energy absorption was possible.

Thermoplastic and thermoset box-beams were manufactured by using compression moulding and resin-transfer moulding, respectively. Woven and warp-knitted fabrics, together with braiding, were used for the preforming. The load-bearing capabilities of the beams were tested in three-point bending. Failures initiated at the compression side of the beams, more noticeably so for the thermoplastic beams. The experimental results are compared with those of a finite-element analysis, and the agreement is reasonably good.     

Heat conductivities of insulation mats based on water glass bonded non-textile hemp or flax fibres

Heat insulation mats based on water glass bonded non-textile flax and hemp fibres were fabricated via a pilot plant, and their heat conductivities investigated. Under the influence of various factors like moisture content, water sorption and diffusion processes, fibre characteristics and heat radiation as well as thickness and apparent density, heat conductivities in the range of 0.0392–0.0484 W/mK for flax fibre mats and 0.0441–0.0592 W/mK for hemp fibre mats were obtained. Strong interactions between the fibre characteristics on the one hand and the water sorption and diffusion processes, the heat radiation, the apparent density and the thickness on the other hand were found. Investigations of tensile strengths and dimension stabilities indicate that the isolation mats are easy to handle and a structural alteration of an overall construction will not occur.     

Optimisation of the surface treatment of jute fibres for natural fibre reinforced polymer composites using Weibull analysis

Abstract

The natural bast fibres such as jute, flax, kenaf, hemp, ramie are chemically modified for improving the interfacial adhesion with the hydrophobic matrices. Alkali treatment is amongst the widely used chemical treatment for the surface modification of these natural fibres. In this study, jute fibres are treated with 0.5, 4 and 25?wt.% sodium hydroxide (NaOH) solution at room temperature for 24?hours, 30?min and 20?min respectively. A comparison has been made between the physical and mechanical properties of these untreated and alkali treated jute fibres. Subsequently, a comparison between the cross-sectional areas of jute fibres before and after alkali treatment by using SEM analysis and circular fibre assumption is also made. The aim of the work is to optimise the alkali treatment processes of jute fibres with different concentrations of NaOH at room temperature. Two-parameter Weibull distribution is also applied to analyse the tensile properties of untreated and different alkali treated jute fibres. It has been observed that probabilistic tensile strength is an effective technique rather than presenting the average tensile strength. The study clearly demonstrates the jute fibre treated with 0.5?wt.% NaOH is more feasible and effective way to improve the mechanical properties of natural fibre reinforced composites.     

A study on thermophysiological comfort properties of fabrics in relation to constituent fibre fineness and cross-sectional shapes

The present study reports the effect of linear densities and profiles of polyester fibres on the physiological properties of their fabrics. Four different polyester fibre finenesses along with microdenier and four cross-sectional shapes (circular, scalloped oval, tetrakelion and trilobal) were selected to produce two sets of 2/1 twill fabrics; one composed of 100% polyester and the other 67:33 P/V blends. In studying the thermophysiological component of the clothing comfort, heat, air and moisture transmission characteristics of the fabrics were assessed. The principal thermal properties, such as thermal absorptivity, thermal resistance and thermal conductivity, were experimentally evaluated, using the Alambeta instrument. The study of the obtained results established the fabrics of non-circular cross-sections as against circular ones, and increase in the linear density results in higher thermal resistance, lower thermal conductivity and lower thermal absorptivity. Wicking behaviour of fabrics was studied under two conditions–wicking from an infinite liquid reservoir (transverse wicking) and wicking from a finite liquid reservoir (single drop wicking into the fabrics). Increase in fibre linear density enhances transplaner wicking but slows down the spreading speed of water drops. Air permeability and moisture vapour permeability are found to be positively correlated with fibre decitex. The role of fibre cross-sectional shapes in influencing mass-flow characteristics is quite considerable. Use of non-circular polyester in place of a circular one augments the wickability of liquid water along with the permeability of air and moisture vapour through the fabrics, revealing their high porosity, which assists air and moisture to propagate. Mixing viscose into polyester brings down the air permeability and moisture vapour transmission rate (MVTR) of fabrics. Results show that moisture absorption of viscose is an important factor in influencing the moisture transport characteristics including both wickability and MVTR of 100% viscose and P/V-blended fabrics.     

Mechanical properties of natural fibre-reinforced composites

Natural fibres were initially used in composite materials to predominately improve bulk and reduce cost rather than improving mechanical properties. But the environmental problems associated with the production and use of synthetic fibres have changed the scenario. In the previous decade, natural fibres have been extensively used as reinforcement materials for both synthetic and bio-degradable matrices. Natural fibre reinforcements have mostly improved flexural and impact properties, but tensile strength improvement has been marginal and has been an area of investigation. Many attempts have been made towards improving mechanical properties, with efforts directed at improving the interface, newer methods of production of composites, new modelling techniques etc. In this detailed review, an attempt is made to critically analyse the various research efforts directed towards improving the mechanical properties of natural fibre reinforced composites.