Journal of the Rubber Research Institute of Sri Lanka
Permanent URI for this collectionhttps://dl.nsf.gov.lk/handle/1/8676
Browse
80 results
Search Results
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 Hand pollination of Hevea brasiliensis in Nigeria (1984-1990). comparison with open pollinated field data(Rubber Research Institute. Agalawatta, 1990) Olapade, E.O.; Omkhafe, K.O.Artificial hand polinations of Hevea brasiliensis were done at the Rubber Research Institute of Nigeria (RRIN) from 1984-1990: these involved 28,887 female flowers from which only 7.60perc. mean fruit set was obtained while only 5.13perc. of the flowers formed fruits that reached maturity. A correlation value of 0.65 was obtained between number of female flowers pollinated and fruits set. Clonal variations were observed for flowers production in the open pollinated field with very high correlation of +0.9 between male and female flowers. Clones PB 5/51 and RRIM 707 produced the highest number of both male and female flowers. The mean male to female flower ratio was 14.1. Male flowers had a higher correlation coeffieciency of r=0.32 with fruit set than emale flowers with r=0.05. An estimate of 15perc. fruit set was obtained under natural open field pollinations in 1989 while only 8.8perc. of the flowers formed fruits that reached maturity. Only about 64perc. of the 64 perc. of the fruits set under both artificial and natural open pollinations reached maturity. While about 36perc. abortions of fruits took place. The implications of these results are discussed.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.Item Use of vegetable oils as fuels for diesel engines with specific reference to rubber seed oil(Rubber Research Institute. Agalawatta, 1990) Perera, E.D.I.H.; Dunn, P.D.This paper considers the use of rubber seed oil (RSO) as a diesel fuel substitute/extender for diesel engines. Experiments were conducted using RSO as a fuel in diesel engines. The physical and chemical properties of RSO were measured. High viscosity in one important difference between this material and diesel oil. Processes were investigated to reduce the viscosity, in particular a transesterfication process was studied. The effect of viscosity and surface tension on characteristics of sprays from injectors was studied in order to identify differences between RSO and diesel oil. The results of these experiments help to explain the observed differences in engine performance between the two fuelsItem 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 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 Effect of soil moisture on establishment success of different planting techniques in rubber(Rubber Research Institute. Agalawatta, 1993) Samarappuli, L.; Yogaratnam, N.; Hettiarachchi, R.