Journal of the Rubber Research Institute of Sri Lanka
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Item Investigation of some factors which effect on rate of evaporation of antioxidants and ultraviolet stabilizers(Rubber Research Institute. Agalawatte, 1996) Goonetilake, S.A.P.P.; Billingham, N.C.Volatility is a physical property which effect the retention of antioxidants during processing and use of polymeric products. The volatility data abtained for such compounds are very useful in choosing an antioxidant for particular application. In this study measurement of volatilities of some phenolic antioxidants and UV stabilizers were done by using an apparartus specially designed for this purpose. It is apparent that the molecular weight and the molecular structure have a significant effect on the evaportion rate of the antioxidants as well as UV stabilizers. The polarity of the compounds also reduces the volatility while the environmental conditions such as vacuum enhances the volatility by a factor of 10.Item Use of blends of glove waste and natural rubber in rubber products manufacture(Rubber Research Institute. Agalawatte, 1996) Seneviratne, W.M.G.; Kumara, P.H.S.; Abeykoon, A.M.C.Substantial amount of defective examination gloves are rejected in glove manufacturing factories in Sri Lanka. These glove rejects cause severe environmental hazards. A series of experiments were therfore carried out to investigate the possibility of recycling these glove rejects and using them as a blend or a filler in the manufactures of rubber products. The results of the experiments indicate that appraciable quantity of recycled glove waste can be blended with NR to give properties comparable to that obtained from NR alone.Item A rapid minipreparation method for DNA extraction from Hevea leaf tissue(Rubber Research Institute. Agalawatte, 1996) Herath, S.; Attanayaka, D.P.S.T.G.; Karunanayake, E.H.Use of DNA markers in plant breeding is increasingly becoming popular. A basic requirement in using this technique in plant breeding is the availability of a simple inexpensive method for the isolation of plant DNA from large populations. Here we describe a rapid method of DNA isolation from Hevea leaf tissue. DNA yields obtained by this method were comparable with the yields of the other available methods. The quality of the DNA was tested by digesting with several restriction enzymes and was found to be of adequate purity. Southern blot analysis of this DNA showed its suitability for RFLP analysis of Hevea.Item The effect of tapping on the assimilation rates of Hevea brasiliensis Muell. Arg. leaves(Rubber Research Institute. Agalawatta, 1990) Nugawela, A.; Aluthhewage, R.K.The CO2 assimilation rates at leaf level were compared in tapped and untaped trees of two Hevea brasiliensis genotypes. In both genotypes, the CO2 assimilation rates of the leaves in the upper stratum were lower in tapped trees. Simmilary, in young microtapped plants the CO2 assimilation rates were lower than in the untapped plants. The decrease in CO2 assimilation rates due to tapping cannot be attributed to an increase in either stomatal or mesophyll limitations. Tapping increases the sink demand for photo assimilates, but it also results in the loss of water, inorganic nutrients and proteins from the plant. Loss of water, inorganic nutrients may results in lower CO2 assimilation rates of the tapped trees. In the long-term this could result in lower sucrose content in the latex. This may be a probable cause for the physiological disorder, tapping panel dryness in rubber.Item Role of potassium on growth and water relations of rubber plants(Rubber Research Institute. Agalawatta, 1993) Samarappuli, L.; Yogaratnam, N.; Karunadasa, P.; Mitrasena, U.; Hettiarachchi, R.Item Seasonal variations in nodule activity of Pueraria phaseoloides (Roxb) Benth(Rubber Research Institute. Agalawatta, 1990) Jayasinghe, C.K.; Parker, C.A.; Kulasooriya, S.A.The age of Pueraria phaseoloides plants had a marked effect upon the rate of acetylene reduction in their nodules. Acetylene reduction activity increased with the age of the plant and maximum efficiency of nodule activity was detected 60 days after sowing, followed by a marked decline on the 120th day and continued at a low rate. Dry matter yield and total nitrogen in plants was more or less constant thrugh out the assay period.Item An investigation on oil of rubber seed (Hevea brasiliensis)(Rubber Research Institute. Agalawatte, 1996) Njoku, O.U.; Ononogbu, I.C.; Owusu, A.J.Y.Oil from seeds of hevea brasiliensis traditionally used as thickening agent for saurce preparation was isolated, and its physical and chemical characteristics determined. Saponification yielded saturated and unsaturated fatty acids which were seperated by preferential crystallization using organic solvents. Methanol, Ethnol, Hexane and Acetone were found effective solvents inthis regard. Gas liquid chromatography (GLC) revealed large amounts of C18 fatty acids as well as traces of other fatty acids. The iodine values show that the solvents used in this study gave excellent yields of fatty acids with acetone being the most effective as a crystallization solvent to oil ratio 3:1 at 5 oC.Item An economic evaluation of the use of rainguards(Rubber Research Institute. Agalawatta, 1993) Rodrigo, V.H.L.; Herath, P.H.M.U.; Nugawela, A.Use of rainguards can minimize the loss of tappping days and hence the loss in rubber crop. A simple model was developed to study different components determinig the profitability of using rainguard is discussed. Price of rubber, yield potential of a plant and tapping wage rate were identified as most important factors which determine the worthiness of the use of rainguards. Sealent price is also a major factor in deciding profitability. If the price of scalent is less than Rs. 20/= per kg, the profilability from both the apron and the gutter types is sameItem Effect of soil moisture on establishment success of different planting techniques in rubber(Rubber Research Institute. Agalawatta, 1993) Samarappuli, L.; Yogaratnam, N.; Hettiarachchi, R.Item Utilization of phosphorus from apatite and growth of plants inoculated with vesicular arbuscular mycorrhiza and phosphate dissolving bacteria(Rubber Research Institute. Agalawatta, 1990) Pathirana, L.S.S.; Waidyanatha, U.P. De S.; Peiris, O.S.An annual grass, Pennisetum ploystechyon (L) Schult and a perennial creeping legume Pueraria phaseoloides took up more P and grew better in an acid soil (pH 4.8) treated with a poorly soluble source of apatite. Inculation of the sterilized soil with a heterogenous mixture of a vesicular arbuscular mycorrhizal (VAM) spores extracted from the soil and with Glomus fasciculatus (E3) spores did not increase plant growth or uptake of P in soil with apatite but growth was increased considerably in soil in soil without apatite. However, inoculation with E3 type spores had no effect on growth or P uptake of Pennisetum . Phosphate dissolving bacteria (PDB) stimulated growth of Pueraria and uptake of P from a soil enriched with apatite.