Browsing by Author "Subramaniam, K"

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item: Conference-Full-text
An appropriate latex-bitumen emulsion blend for road surfacing
(1998) Subramaniam, K; Sivarajan, TK
Natural rubber modified bitumen is a valuable material for road surfacing. It enhances the strength and durability of the road surface better than the bituminous material alone. It can be produced by incorporating natural rubber in the form of powder in to hot bitumen or by mixing latex into bitumen emulsion. The latter process is most beneficial to road engineers as the blend is a water based liquid which can be applied on road surfaces directly, by spraying. The process of blending natural rubber latex with bitumen emulsion has been investigated in this work. From the studies, suitable formulations for preparing bitumen emulsion and blend of latex bitumen emulsion for road surfacing have been identified.
item: Conference-Abstract
An appropriate method of production of rubberised bitumen for road surfacing
(Engineering Research Unit, Faculty of Engiennring, University of Moratuwa, 1996-05-31) Subramaniam, K; Raveendran, K; Thiruchelvam, AT
item: Article-Full-text
An appropriate method of production of rubberrised bitumen for road surfacing
Subramaniam, K; Thiruchelvam, AT; Raveendran, K
A laboratory scale method comprising two stages has been developed to produce rubberised bitumen based upon natural rubber. In the first stage of the method, natural rubber in the form of field latex, stabilised previously with ammonia and potassium hydroxide, was added in required proportion into 80/100 grade bitumen melt at 95°C, to give about 3% rubber in bitumen by mass. To facilitate the addition, the contents were continuously stirred by means of a multi-stage impulse counter current impeller (pitched paddle stirrer). In the second stage, the resulting temperature of the mix ' was gradually raised to 100°C. to vapourise the water content in the latex. The problems encountered during the vaporisation of water such as frothing, and rise in viscosity of the mix were overcome by altering the speed of the stirrer unit appropriately. The bitumen-rubber blend thus obtained, on testing for its quality, exhibits bettei technical properties than 80/100 grade bitumen for application in road surfacing
item: Conference-Full-text
Cashew nut shell liquid based polymer resin for making air- drying varnishes
(2000) Subramaniam, K; Fernando, S
As cashew nut shell liquid (CNSL) is a natural source of phenols, attempts are made in this work to prepare a synthetic polymer resin from the liquid, by treating it with formaldehyde. The polymer resin thus prepared is then assessed for its efficiency as a film -former in air- drying varnish formulations. For the assessment, the resin is compared with the commonly used air - drying varnish film - former, short oil soya alkyd resin (60% solids content). The studies reveal that the CNSL - based resin prepared in this work is most applicable as an extender resin rather than a sole resin in air drying varnish formulations.
item: Thesis-Abstract
Characterization and evaluation of starch xanthide encased powdered natural rubber
Maduwage, S; Amarasinghe, ADUS; Subramaniam, K
Rubber as a free-flowing powder, is essential in order to stream line the manufacturing processes of rubber goods. The previous works noted the importance of using powdered rubber as a competitive raw material for continuous processing in rubber industry. However, in most of these works, the study was continued to the synthetic rubbers and only a few had been reported on the natural rubber. Sri Lanka which is an agricultural based country, has a bulk quantity of natural rubber field latex at a low price. Hence, it is worthwhile to produce a value-added product like powdered rubber using field latex. Encapsulation is a common process in preparing powdered natural rubber. In this process, starch xanthate, SX, which acts as a diluent/reinforcing filler, behaves as an encapsulating agent for latex particles. The level of encapsulation as well as the properties of the resulting powder is highly dependent on the strength and the amount of the SX solution. The present work investigates these effects with varying strength of SX by changing the degrees of substitution, DS, of the SX solution and also the loading of the SX. The lower and the upper limits of DS of SX examined were 0.07 and 0.35 and the results suggested that the intermediate DS levels were more promising. The physical properties of the final vulcanizates were found to be satisfactory and were comparable with the rubbers available in the market. Study on drying techniques established the necessity of water washing step for natural rubber powders to remove non-rubber substances and the applicltion of an anti-cake agent to prevent agglomeration during drying. The effect of different anti-cake agents such as zinc stearate, talc powder and whiting was examined and zinc stearate was found to be the best out of the anti-cake agents used. Highly friable crumbs that ground readily to give powders were obtained with oven drying rather than with sun drying.
item: Thesis-Abstract
Designing resin-rubber sole compounds for use in local shoe manufacturing industry
Ranatunga, RRMSK; Subramaniam, K; Abeysirigunawardena, W
Natural rubber and Reclaimed rubber based resin- rubber soling sheets compounded with various cheap rubber ingredients were made and evaluated in this work for their use in local shoe manufacturing industry. In the experimental work, natural rubber and reclaimed rubber compounds formulated with different ingredients were prepared and moulded into sheets by compression moulding technique. The surfaces of the sheets were abraded and then crated with different flexible colour-paints. The painted (Coloured) sheets produced were then tested and evaluated for resin- rubber shoe sole sheets. The investigation reveals that the compounds containing the peptised natural rubber (SLR 20) and reclaimed rubber (DSI-Super fine grade) are found to be the most appropriate compounds for the production of resin-rubber soles in the local rubber industry.
item: Thesis-Abstract
Investigation of blooming on non black NR - based straps of rubber slippers
Munasinghe, MAA; Subramaniam, K
Blooming is the appearance of powdery deposits on the surface of a rubber product. It occurs, whenever a rubber product contains an incompatible ingredient in excess of soluble quantity. Blooming is considered to be a major defect in rubber products. It spoils the smooth shiny rubber surface and impairs the aesthetic appeal of the product. Blooming can also aid passage of air to the rubber mass and thus can cause oxidative degradation of rubber molecules. Since this blooming phenomenon (defect) occurs very often in non - black Natural Rubber (NR) - based straps, the important tension - members of rubber slippers, an investigation has been made in this project with a view to rectify the defect and improve the breaking strength of straps. The results of investigation reveal that the blooming of the strap is caused by the insoluble phenolic antioxidant which is a component of the protective system that has been added in excess quantity, into the rubber. Further it has also been found that about a 15% reduction in the amount of phenolic antioxidant added and inclusion of 0.15 pphr of zinc - di-ethyl dithiocarbamate completely prevent the bloom, and impart desirable aging resistance to the rubber..
item: Thesis-Abstract
Investigation of NR-EPDM blends for improving Ozone resistance of tyre side wall
Kumara, SADS; Subramaniam, K
In this project, attempts have been made to improve the properties of Natural rubber (NR) tyre sidewall compound, especially the ozone resistance by blending the rubber with Ethylene propylene diene monomer rubber (EPDM). In view of this, various rubber compounds, containing the blends of NR and EPDM in the different proportions have been prepared, vulcanized and tested for their physical strength and ozone resistance. The results of this investigation reveals that the blends containing NR:EPDM in the range of ratios from 70:30 to 80:20 are most suitable for the production of tyre sidewalls with high strength and ozone resistance.
item: Conference-Full-text
Locally producible castor-oil based surfactant for production of nr-latex foam
(Engineering Research Unit, Faculty of Engiennring, University of Moratuwa, 1995-03) Subramaniam, K; Satharasinghe, WNN; Dias, WPS
A surfactant plays an important role in a colloidal system such as natural(NR) latex. It decreases the surface free energy at the interface between the rubber particle and aqueous phase, thereby enhancing the stability of the latex. Of all the surfactants that are applicable in NR-latex'.the anionic types of unsaturated long chain molecules have been, found to be most suitable for the production of NR-latex foam.typically the organic compound K-oleate. Although locally producible K-soap of castor oil has been identified as an alternate surfactant to K-oleate,no detailed studies have been made on its performance in NR-latex,in relation to that of K-oleate. It is with this-concern that-this paper is presented. In this work,the K-soap of castor oil has been prepared and then compared with K-oleate for’siirfattive; performance,especially for stabilising and form promoting effects in NR-latex. The investigation of the results of the studies reveals that in respect of these effects K-soap of castor oif functions more effectively than K-oleate.
item: Conference-Full-text
Preparation and properties of starch xanthide encased powdered natural rubber
(2000) Amarasinghe, ADUS; Subramaniam, K; Maduwage, S
Starch xanthide encased powdered natural rubber was produced by oxidatively co- precipitating the mixture of starch xanthate solution and natural rubber field latex under vigorous stirring. The resulting finely divided wet powdered rubber particles were separated by filtration and then converted to free-flowing powders by oven drying. The level of encapsulation as well as the properties of the resulting powder was highly dependent on the strength and the amount of the Starch Xanthate (SX) solution. The lower and the upper limits of Degree of Substitution (DS) of SX examined were 0.07 and 0.35 and the results suggested that the intermediate DS levels were more effective. The physical properties of the final vulcanizates were examined and found to be comparable with the rubbers available in the market.
item: Thesis-Abstract
Reclaimed rubber from buffing dust-by means of a simple method of plasticization
Fernando, JMP; Subramaniam, K
A simple method of reclaiming rubber from buffing dust, the major rubber reject of Sri Lankan tyre retreading rubber industries is identified. In the procedure, buffing dust which has been swollen previously with SM 20, the aromatic rubber process oil in various proportions is plasticized with 1 part, by weight of Zinc: salt of Pentachlorophenol, the common peptizer on a warm two roll mill temperature70° - 80°C. The effects produced by the variables such as amount of oil absorbed, and time of mastication on the degree of plasticity of the softened buffing dust mass are investigated and from the results a simple efficient method of reclaiming rubber from buffing dust is chosen. A sample of the reclaimed rubber mass, produced by this particular method, when it is compounded with ingredients and blended with Natural rubber, show valuable technical properties during processing and in vulcanisates.
item: Thesis-Abstract
Use of some castor oil derivatives as surfactants in NR latex industry
(2014-07-07) Satharasinghe, WNN; Subramaniam, K
Surfactants which find applications in local NR latex industry are chiefly imported chemicals. With a view to replace some of these chemicals with locally producible materials, in this study, castor oil extracted in this country was converted chemically into its derivatives - castor soap (potassium ricino-leafee) and sulphated castor oil. The effects of addition of each derivative on the stability and foaming behaviour of NR latex and on emulsification of a liquid softener (paraffin oil) were investigated. Further, the derivative, sulphated castor oil was also tested for its suitability as a dispersing agent in the preparation of an accelerator (ZMBT) dispersion. To assess the performanc-es of these derivatives in the above determinations, parallel tests were also carried out using potassium oleate in the first two tests and Dispersol LN (sodium salt of naphthalene formaldehyde sulphonate ) in the third test.