PROCESSING CHARACTERISTICS, MECHANICAL BEHAVIOUR AND WEAR PROPERTIES OF URENA LOBATA (CAESER WEED) FIBER REINFORCED POLYMER MATRIX COMPOSITES

Abstract

This study is on the processing characteristics, mechanical behaviour and wear properties of Urena lobata (Caeser weed) fiber reinforced polymer composites. Fibers were extracted from Urena lobata plant by water retting. The retted fibers were subjected to chemical treatments with NaOH solution of varying concentrations (3, 6, and 9) wt%. The compositional analysis of the untreated and differently-treated Urena lobata fibers were carried out. Mechanical behaviours and morphological characterizations, physical and wear properties of the untreated and differently-treated Urena lobata fibers were investigated. Structural characterizations which include; X-ray diffraction (XRD), thermo-gravimetric analysis (TGA) and Fourier Transform Infra-red Spectroscopy (FTIR) were carried out on the untreated and treated (6 wt%) Urena lobata fibers. The untreated and treated U. lobata /PP composites were produced by compression moulding at varying weight percents of the fibers (5, 10, 15, 20 25, 30, 35) wt%. The mechanical (Young’s modulus, elongation at break and tensile strength) and morphological behaviours of untreated and differently- treated (3, 6 and 9) wt% U. lobata fibers showed enhanced properties with the treatment of U. lobata fibers at 6 wt% NaOH solution. The mechanical behaviours (hardness, tensile strength, Young’s modulus, elongation at break, impact strength, and interlaminar shear strength); and morphological characterizations were carried out on the untreated and 6 wt%-treated U.lobata/Polypropylene (PP) composites. The fibers treated with 6 wt% NaOH solution showed improved compositional constituents and mechanical properties (261.13 ± 0.045 MPa, 5.33 ± 0.01 GPa and 2.91 ± 0.01% for tensile strength, Young’s modulus and elongation at break, respectively) amongst other alkaline-treated fibers. The XRD results showed that the treated fibers have more Crystallinity index (0.76) and %Crystallinity (80.5%) than the untreated ones with Crystallinity index of 0.56 and %Crystallinity of 69.4%. The FTIR spectra confirmed that the treated and untreated Urena lobata fibers are natural fibers with O-H stretching 3261 and 3337 cm-1 respectively. And also, that there was the removal of hemicelluloses after alkaline treatment for strong carbonyl (C=O) stretching of 1738 cm-1 that was present in the untreated was not found in the treated. From the results, increasing fiber loading (5, 10, 15, 20, 25, 30, and 35) wt% increased the mechanical properties of both the treated and untreated U.lobata/PP composites, except for the Young’s modulus. Also, there was improvement in the density and wear resistance of the treated composites. The improvements were attributed to enhanced fiber-matrix adhesion of the alkaline treated U.lobata fibers. Thus the 30 wt% Urena lobata fibers loading showed the optimum fiber loading, (with improvement in tensile strength (2 – 22%), percentage elongation (5 – 26%), and impact strength (2 – 19%)); for the production of Urena lobata/PP composites for applications in automobile parts; with a decline in mechanical properties at 35 wt% fiber content. Also, the treated U.lobata/Polypropylene (PP) composites showed better thermal stability (445oC) than the untreated ones (443oC). Thus, the Urena lobata fiber reinforced polypropylene composites produced in this study can be well suited for applications in automobile parts such as dashboard parts, gaskets, headliners, and construction decking.