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.

Rice husk silica blended fillers for engine mount application

“…Agricultural residues are anticipated to be a growing engineering material not just considering the technological aspect, but also taking into account the social and environmental aspects., as indicated by a variety of contemporary economic, ecological, and production policies established by governments 1 , 2 . This has led to continuous investigations and the application of bio-based sustainable materials to replace the prevalent materials utilised in the field of engineering manufacture over the period of the last five decades 2 – 4 . These bio-based materials have been proven to be feasible and successful alternatives to conventional materials when it comes to cost reduction, savings in energy, the impact on the environment and even manufacturing economics 5 – 8 .…”

“…In addition to generating serious health problems such as cancer 23 , the production of these conventional fillers causes irreversible environmental damage. Commercial silica, which is presently used as a replacement for carbon black, especially in tyres and rubber mount compounds, generates a large quantity of wastewater, resulting in a high level of environmental contamination, and consumes a significant amount of energy during its processing phase 4 , 24 . These difficulties have paved the way for the development of emerging environmentally friendly alternatives, such as the utilisation of silica obtained from rice husk 25 , 26 .…”