Browsing by Author "Gnanasubramaniam, M."

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    Enhancement of physical properties of natural rubber vulcanizates by incorporating rice husk ash with carbon black as a filler
    (Uva Wellassa University of Sri Lanka, 2015) Gnanasubramaniam, M.; Premachandra, J.K.
    There is a higher demand for carbon black and silica as reinforcing fillers in manufacturing of various rubber products which enhance the properties such as modulus, tensile strength, resilience and hardness of vulcanized rubber. Because of their increased prices, it has become a major concern for finding new fillers replacing carbon black and silica. One of the possible candidates in this regard is rice husk ash (RHA) which is an agricultural waste causing environmental pollution (Chuayjuljit, et al., 2001). RHA mainly consists of silica and carbon. Two types of RHA, white rice husk ash (WRHA) and black rice husk ash (BRHA) can be produced by controlled burning of rice husk (Sarkawi, et al., 2003, Ramasamy, et al., 2013). In this research the use of WRHA and BRHA as fillers in enhancing the properties of natural rubber vulcanizates replacing carbon black was investigated. Methodology Two cylindrical metal baskets, one is smaller than the other, were placed coaxially and space between the cylinders was filled with dried rice husk. Ignition was done inside the small basket which contained small holes. It formed a little smolders which slowly spread into the rice husk facilitating controlled burning (Allen, 2004). The burning was continued for a day and obtained WRHA. In order to produce BRHA the dried rice husk was burnt in an open place for an hour. Both WRHA and BRHA were sieved to obtain particles with a size range from 150 μm to 300 μm. Rubber compounding formula for tire side wall was used to prepare the natural rubber (RSS 1) compounds with different amounts of fillers. A series of rubber compounds having varying amounts of carbon black (N 330) and BRHA filler. Mixing of the ingredients was carried out in an internal mixture followed by mixing on a two-roll mill for 5 minutes at 80 °C. Two rubber compounds were prepared varying the amounts of carbon black (N 330) and WRHA filler employing the same mixing process. Investigating the processing characteristics of the resulting compounds using a Rheometer, optimum curing time for each sample at 150 °C was determined. The rubber samples were prepared by curing the compounds in a hydraulic press at 150 °C for relevant curing time periods. The tensile properties of resulting vulcanizates were determined following ASTM D412 standard using Instron machine model 2713. For tear testing the same machine was used following ASTM D- 638 standard. Hardness test was performed using Elastocon machine following IRHD standard. Result and Discussion The samples were designated according to the types of fillers and the amounts of fillers in grams incorporated. In the designation the letters C, B and W represent the presence of carbon black, WRHA and BRHA, respectively. Each number following the each letter in the sample designation represents the amount filler in grams present in each sample. Variation of the tensile strength upon the filler composition in samples is shown in Figure 01. Values of tensile strength of all the rice husk ash containing samples are considerably higher than that of the reference sample which contains only carbon black. The samples C81B54, C27B108 and C67.5B67.5 show tensile strength values greater than 20 MPa. Tensile strength of C67.5B67.5 is little less than the doubled value of the tensile strength of reference sample. The improvement of tensile strength of RHA containing rubber samples can be attributed to enhanced rubber-filler interaction and good filler dispersion in the rubber matrix. This is resulted by relatively high surface area of small RHA particles enabling better wetting of the particles by the rubber matrix (Onyeagoro, 2012).
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    Study the Effect on Physical Properties of Rice Husk Ash and Carbon Black Filled Natural Rubber Vulcanizates
    (Uva Wellassa University of Sri Lanka, 2016) Gnanasubramaniam, M.; Premachandra, J.K.
    Rice husk ash is mainly composed of silica and carbon black remaining from incomplete combustion. Both silica and carbon black have long been recognized as the main reinforcing fillers used in the rubber industry to enhance certain properties of rubber vulcanizates, such as Hardness, Resilience and tensile strength. In this study, two grades of rice husk ash (low- and high-carbon contents) were used as filler in natural rubber. Comparison was made of the reinforcing effect between rice husk ashes and carbon black. The effect of these fillers on cure characteristics and mechanical properties of natural rubber materials at various loadings, ranging from 0 to 45 pphr, was investigated. The incorporation of RHA into natural rubber improved curing properties, tensile strength and hardness of rubber compound. But decreased tear strength, abrasion resistance, and Young's modulus of the compound. However, RI-IA gave a better resilience property, and Elongation than that of carbon black. Altogether the rice husk ash filled rubber product gave cost reduction and comparable mechanical properties like carbon black fillers. Keywords: Resilience, Abrasion, Young's Modulus