Preparation and characterization of chemically treated coir reinforced polypropylene composites

Abstract

In the present work, different type~ of coir fiber reinforced polypropylene (PPj composites were preparcd by injection moulding technique. To prepare improved coirpolypropylene composiles, various typcs of chcmical trcatments were carried out. Unbleached raw coir fiber was modificd by o-hydroxybenzene diazonium chloride and sodium periodate oxidation. Rcaction parameter (pH) of o-hydroxybenzene diazonum chloridc was varied al3, 7 and 10.5. Coupling reaction on oxidizcd coir was carried out using 2,4-dinitrophenylhydrazinc and urca. FT-IR spcctroscopic analyses wcre donc for all chcmical treatments and the result~ showed the evidence of positive reactions. The effects of2,4-dinitrophcnylhydrazine, o-hydroxybenzene diawnum chlor,ide and urea on the physico-mechanical properties of the composiles were studied. The effc<:tsof fiber content on the physico-mechanical propertics of composites were also studied by preparing composites with different fiber content (10,15,20 and 25 wt%) for each type of composite. Mechanical properties (tensile strength, tensile modulu~,flexuml strength, flexural modulus, charpy impact strength, hardness and water absorption) were measured for all raw and treated eoir oompo~iles.Improved mechanical properties were obtained for all treated composites over untreated raw coir reinforced polypropylene composites. Scanning electron micrographs of the composites were taken to investigate the inlerfacial adhesion and bonding between the fiber and polypropylene matrix resulting from the various chemical treatments. Improved interfacial inlemclions were found for treated composites than untreated composites. Water absorption te~ls were carried out of all eompositcs to investigate thc effect of chemical treatment on the moisture absorption characteristic of hydrophilic coir in the eoir-polypropylene composites, which has direct effect on the dimensional stability of the composites. Reduced water absorption was fonnd for oxidized ooir-polypropylene composites. 0- hydroxybenzene dia;;onum chioridc trealcd cOlr composites und 2,4- Dinitrophenyihydrazine treated oxidized and urea treated oxidized coir-polypropylene I composites. urea treated specimens yielded the bcst set of mechanical properties. B~ed r on fiber loading, 25% fibcr reinforced composites had the best sct of mechanical properties among all composites manufactured.