Jute fiber with thermoplastics

One of the biggest new areas of research in the value-added area is in combining natural fibers with thermoplastics. Since the price of plastic has risen sharply over the past few years, adding a natural powder or fiber to plastics provides cost reduction to the plastic industry (and in some cases increases performance as well), but, to the jute and kenaf industry, this represents an increased value for the jute and kenaf component. 

The surface energy of fibers is closely related to the hydrophilicity of the fiber [6]. Some investigations are concerned with methods to decrease the hydrophilicity. The modification of wood-cellulose fibers with stearic acid [10] hydrophobizes those fibers and improves their dispersion in polypropylene. As can be observed in jute reinforced polyester composites, treatment with polyvinylacetate increases the mechanical properties [10] and moisture repel-lence [60]. Several similar investigations on biobased composites based on thermoplastic and thermoset matrices have been reported by several authors [61-63]. Some of the major findings based on the authors own experimental investigations are discussed in the following sections. 

Table 2.10 Jute fiber (40 wt%) isotropic lay-up RP tensile properties with thermoplastics...

A particularly promising route is to treat the fiber with a phenolic resin based on cardanol formaldehyde (CF). This is a natural alkyl-phenol, in which the methylol groups are able to react with the hydroxyl groups of the cellulose, while the long C-15 alkyl group of cardanol facilitates the formation of an adhesive bond with non-polar TPs. It is concluded that Jute fiber thermoplastic RPs can bear comparison with glass fiber RPs. However, the best solution may well be a combination of treated jute with glass. 

Research to develop jute and kenaf fiber thermoplastic alloys is based on first thermoplasti-cizing the fiber matrix as described above, followed by grafting of the modified fiber with a reactive thermoplastic. This type of composite has the thermoplastic bonded onto the jute or kenaf so there is only one continuous phase in the molecule. This is done in one of two ways. In one case, the matrix is reacted with maleic anhydride that results in a double bond in the grafted reacted molecule. This can then be used in vinyl-type additions or in free radical polymerization to either build a thermoplastic polymer or graft one onto the jute or kenaf backbone. In the second method, the matrix is reacted with a bonded chemical and then reacted with a low-molecular-weight thermoplastic that has been grafted with side-chain anhydride groups. 

Kenaf is now being grown in several countries where the bast fiber is used for geotextiles and the pith is going into sorbents for oil spill clean up and animal litter. The production of pulp and paper from kenaf is growing, but it is only used for limited types of papers at present. The utilization of the whole plant of both jute and kenaf is under consideration for structural and nonstructural composites. Automotive interior door panels are now produced in Germany and the United States out of jute and kenaf bast fiber in combination with thermoplastics. 

The demand for better fuel efficiency based on the strict governmental regulations on safety and emission has led to the wide application of composites and plastics in the automotive industry in the place of the traditionally used steels [32]. Thermoplastic materials reinforced with natural fibers have reported to have excellent mechanical properties, recycling properties, etc. [33-36]. Several natural and biorenewable fibers such as wheat, isora, soybean, kenaf, straw, jute, and sisal are used in the fiber/plastic composite industry, and the use of namral fibers as reinforcements for composite has attracted many industries [37, 38]. Compared to polymer resin, polymer biocomposites that are reinforced with natural fibers have many applications due to its ease of processing, comparatively lower cost, and excellent mechanical properties [39]. For more than a decade, European car manufacturers and suppliers have been using natural fiber-based composites with thermoplastic and thermoset matrices. These biocomposites and bionanocomposites... 

The lignocellulosic materials mostly used as fillers in thermoplastic composites include wood flour, starch, rice husk and a wide variety of vegetable fibers available such as jute, sisal, flax, hemp, coir, banana, pineapple, among others. And whenever vegetable fiber reinforced thermoplastic composites with higher properties are needed, possible solutions include improved adhesion, better fiber orientation, and filler hybridization with synthetic fibers or mineral fillers. The latter solution is an intermediate alternative regarding environmental friendliness, cost, weight and performance compared to an all synthetic composite [12,26]. 

Alkali treatment of jute fibers also improves the mechanical properties of thermoplastics. The vinyl ester resin reinforced with alkali-treated fibers shows improved mechanical properties. The maximum improvement was noted for the composites prepared with 4 h alkali-treated fibers at 35% fiber loading. The flexural strength improved by 20% and the modulus by 23%. The strength and modulus of the composites were found to be lower than the values estimated from the general rule of mixtures. For the jute/vinyl ester composites with 35% fiber content, the strength was decreased by 29% and 16% for the untreated and 4h alkali-treated fibers and the modulus was lower by 51% and 37% for the untreated and 4h alkali-treated fibers, respectively [154]. 

Current research indicates that there is a growing interest in natural fibers. Natural fibers Ifom jute were tested in thermosetting and thermoplastic resins. Lignin fillers were used in phenol-formaldehyde, SBR, SBS, and S1S ° and with good results. The opportunities for applications of natural fibers in industrial products have been the subject of recent reviews. Cellulose whiskers with a high reinforcing value were obtained from wheat straw. " Wood fibers were found applicable to such diverse materials as polypropylene... 

Reinforcement of thermoplastic and thermosetting composites with cellulose fibers is increasingly regarded as an alternative to glass fiber reinforcement. The enviromnental issues in combination with their low cost have recently generated considerable interest in cellulose fibers such as isora, jute, flax, hemp, kenaf, pineapple leaf, and man-made cellulose fibers as fillers for polymer matrices-based composites. 

Polymers reinforced with cellulose fibers have received much attention in recent years because of their low density, nonabrasive, combustible, nontoxic, low cost and biodegradable properties. Several authors have reviewed recent advances in the use of natural fibers in composites like flax [ 1 ], jute [2,3], straw [4], kenaf [5,6], coir [7-9], fique [10], among others. Natural fibers have been used to reinforce thermoplastics and thermosets polymers in automotive and aerospace applications [11]. The influence of surface treatments of natural fibers on interfadal characteristics was also studied [12-17], and Joshi et al. [18] compared the life-cycle environmental performance of natural fiber composites with glass fiber composites. In this study, natural fiber composites were found to be environmentally superior in most applications. 

Pultrusion is a modern technique used for producing continuous fiber-reinforced profile in which the orientation of the fiber is kept constant during cure. Although this process is utilized for both thermoplastic and thermoset resins, it is mainly suitable for thermosetting resins like polyester, epoxy and phenolic resin systems. Jute, available in continuous forms such as mat, roving, tapes, yarn, etc., is impregnated with... 

A number of reviews have been studied on the potential of natural fibers such as sisal, kenaf, hemp, flax, bamboo, and jute for the preparation of thermoplastic composites. In this work, however sisal fiber (SF) has been used as reinforcement due to easily availability and comparatively low cost. The xmtreated and treated SF-reinforced RPP composites have been prepared and investigated their thermal, mechanical, morphological, weathering and impact properties. An improved mechanical, thermal, and morphological property has been observed for chemical treated SF as well as clay loaded RPP. The analysis revealed that SF-reinforced RPP composites with enhanced properties can be successfully achieved which warrants to replace the synthetic fillers-based conventional thermoplastic composites. These SF-based RPP composites can be the material of choice in the field of aeronautic, automobiles, civil engineering, etc., due to its low cost, low density, non-toxicity, recyclability, acceptable strength, high specific properties, and minimum waste disposal problems. 

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