Rice husk ash reinforced natural rubber composites: effect of benzene diazonium salt treatment.

Abstract

Rice husks are a major agricultural residue with growing volume in Nigeria in recent times owing to the country’s drive for self-sufficiency in rice production. Rice husks have great potential for use as fillers in biocomposites for applications in the manufacture of engineering products. However, the hydrophilic nature of this agricultural residue limits its choice as fillers in biocomposites. This study focused on the modification of the hydrophilic property of rice husks through treatment with benzene diazonium salts in different media (pH levels of 7, 9, 10.5 and 12) to attain the most suitable treatment media for processing rice husks. The treated samples were burned in a furnace at a temperature of 600oC for 6 hours. The compounding of the rice husk ash, CV-60 natural rubber and additives were done on a two-roll mill at a speed ratio of 1:1.25 with rollers temperature of 70oC and cured in a hydraulic press at 130oC for 20 minutes at 2.5 MPa. The composites were developed using rice husk ash as the filler with loadings of 30, 34, 38, 42, 46 and 50 phr. Characterizations and tests carried out include Fourier transform infrared spectroscopy (FTIRS), X-ray fluorescence (XRF), shore A hardness, compressive strength and tensile strength. The composites developed using pH 10.5 treated rice husks yielded the highest silica content and showed better adhesion characteristics. The sample with 42 phr loading gave better mechanical properties with tensile strength, compressive strength, and tensile modulus of 18.5 MPa, 39.72 MPa and 7.87 MPa respectively with a corresponding shore A hardness of 45.32. The rice husk ash filled natural rubber composites can find application in the development of vibration isolation mounts.