Effect of pretreatment with detergent on mechanical properties of photocured coir (Cocos nucifera) fiber with ethyleneglycol dimethacrylate

Abstract

Coir fibers were treated with ethylene glycol dimethacrylate (EGDMA) mixed with methanol (MeOH) under UV radiation. A series of solutions of different concentrations of EGDMA in methanol along with a photoinitator, Irgacure-500 (mixture of 1-hydroxylcyclohexylphenylketone and benzophenonc), were prepared. Monomer concentration, soaking time, and radiation intensity were optimized in terms of polymer loading (PL) and mechanical properties. EGDMA (50%), 5 min soaking time at the 4th pass of radiation, produced higher PL and tensile strength (TS), and the values of PL is 17% and TS is 1.3 times of the nontreated one. Then, coir fiber was pretreated with detergent and then treated with the optimized monomer formulation, which exhibited a higher PL of 69% and produced TS of the coir fiber of 4.4 times of the nontreated one. Coir fiber pretreated with detergent along with UV radiation showed the highest TS, which is 18.2 times of nontreated one. Water uptake, degradable properties, and simulated weathering of treated and virgin fibers were also monitored, which showed that EGDMA treatment under UV radiation improved the degradable property.

Preparation and characterization of polypropylene composites reinforced with chemically treated coir

“…This indicates that there is poor interfacial adhesion between the fiber and the matrix (image a). The removal of surface impurities upon chemical treatment makes the fiber rougher with an increase in surface area than that of the raw fiber [21]. This paves the way for better fiber-matrix interlocking and improvement in the mechanical properties of the composites.…”

“…This imparts weak fiber-matrix interaction in the composites with poor mechanical properties. Chemical treatment removes the impurities of coir fiber and makes the coir surface rougher and cleaner [21]. This improves the interlocking between the fiber and the matrix.…”

“…Because of its hydrophilic nature, it is not suitable for compounding with hydrophobic polymer matrix. However, the efficiency of coir as reinforcing fiber has been reported to be improved upon modification of the coir fiber by different physical and chemical methods [21][22][23]. Here, we have shown that a simple two-step fiber treatment technique can significantly reduce the hydrophilic nature of coir as evidenced from the infrared spectral analysis of raw and treated coir along with the physicomechanical properties of the composites.…”

“…This phenomenon becomes particularly important when the interfacial adhesion is weak and if there are micro-spaces that may originate during compounding process because of incomplete wetting of the fiber by the matrix. In connection with the problem mentioned above a number of fiber surface modification techniques have appeared in the literature [17][18][19][20][21][22][23][24]. In all these studies, optimization of fiber-matrix interfacial wetting with a view to improving the physico-mechanical properties of the composite has been the center of attention.…”

“…Coir is a natural fiber obtained from the outer shell of matured coconut and contains cellulose (43 %), lignin (45 %), hemicellulose (0.25 %), pectin (3 %) and other materials [21,22]. Because of its hydrophilic nature, it is not suitable for compounding with hydrophobic polymer matrix.…”