MUNASINGHE E.S.,Rubber Research Institute of Sri Lanka |
RODRIGO V.H.L.,Rubber Research Institute of Sri Lanka
Experimental Agriculture | Year: 2017
Rubber is usually cultivated for lifespan of 30 years based on the technical feasibility of managing tapping panels. For obtaining early financial benefits, there is a demand for shorter lifespan with intensified tapping. With no research conducted on this line, the present study was focussed to investigate the financial feasibility of shortening the lifespan of rubber trees through lifecycle analyses with three principal scenarios of intensified harvesting, i.e. Intensified Harvesting throughout the Total harvesting Period to obtain a part or full amount of yield lost due to shortening the lifespan (IHTP), Intensified Harvesting only during last 6 Years (IH6Y) and Intensified Harvesting at last ¼ of harvesting Period (IH¼P). In IHTP, intensified tapping to achieve 10–15% of yield loss due to shortening the lifespan was found to be effective to reduce the lifespan even up to 21 years. Market price of rubber and tree stand per hectare were found to be the critical factors determining the best lifespan particularly in IHTP. The best lifespan under IH6Y and IH¼P scenarios was in the range of 19–22 years. Agronomic, environmental and social implications in shortening lifespan of rubber are discussed. Copyright © Cambridge University Press 2017
Kudaligama K.V.V.S.,Rubber Research Institute of Sri Lanka |
Thurul W.M.,Thurul Safe Environment |
Yapa P.A.J.,University of Sri Jayewardenepura
Journal of Rubber Research | Year: 2010
Crepe rubber industry is one of the major water polluting industries in all rubber growing countries. There is a necessity to develop suitable treatment technologies for the management of this problem. Covered Activated Ditch (CAD) type test reactors set with Bio-brush media are very effective in rubber factory wastewater treatment. Out of four organic loading rates (OLR) and five specific surface areas (SSA) of media tested respectively, Bio-brush media with 200 m2/m3 SSA under 1.0 COD kg/m3/d OLR was selected as the best for CAD reactors and the average COD removal achieved was about 89%. Results revealed that at higher OLR, correction ofpH could be avoided for an efficient treatment and reactors with higher SSA of media were able to tolerate organic shock loads comparatively. The efficiency of treatment increased with increasing SSA of media and no special cycles were observed in removing biomassfrom the test reactor under any of the four OLRs tested. During maturation, chemical oxygen demand (COD), pH and suspended solids (SS) of treated effluent with 200 m 2/m3 SSA were about 100 mg/L, 6.7-7.2 and 26-43 mg/L respectively which were below the maximum desirable levels stipulated by the Central Environmental Authority of Sri Lanka. Apart from the rubber industry, CAD reactors could also be used for treating biodegradable liquid waste such as waste from the palm oil industry, rice processing industry, sugar industry and others.
Munasinghe E.S.,Rubber Research Institute of Sri Lanka |
Rodrigo V.H.L.,Rubber Research Institute of Sri Lanka |
Gunawardena U.A.D.P.,University of Sri Jayewardenepura
Experimental Agriculture | Year: 2014
In addition to latex and timber, the rubber tree is useful in the alleviation of rural poverty and also in the mitigation of climate change through fixing atmospheric CO2 as biomass. For developing any rubber-based carbon projects, protocols for quantifying biomass and carbon fixed are required. In this context, the present study was aimed at building up allometric models using simple growth indicators (i.e. tree diameter and total height) to assess the timber, biomass and carbon in rubber trees and also to quantify their ontogenetic variation under average growth conditions in two major climatic regimes (i.e. wet and intermediate) of Sri Lanka. All models developed were in the accuracy level of over 88%. The mean absolute percentage error in the validation of allometric models was only 12.9% for timber and less than 5% for biomass and carbon. Under average growth conditions, 1 ha of rubber could produce 208 m3 timber, 191 MT biomass and fix 78 MT carbon during its 30-year lifespan in the wet zone and ca. 16% lesser values in the intermediate zone. The applicability of the findings in carbon trading is discussed. Copyright © 2013 Cambridge University Press.
Wimalagunasekara T.U.,Wayamba University of Sri Lanka |
Edirisinghe J.C.,Wayamba University of Sri Lanka |
Wijesuriya W.,Rubber Research Institute of Sri Lanka
Journal of Rubber Research | Year: 2012
Farmers ' individual choices relating to agronomic practices are influenced by socio economic factors related to the farmer and his family as well as physical factors relating to the farm. Many studies that investigate these choices fail to recognise the importance of neighbours' influence on decision making. This research attempted to determine whether there exists a relationship between one farmer's choice and the choices of the neighbouring farmers in adoption of fertiliser recommendations in rubber cultivation of a sample of 393 smallholder farmers in one of the non-traditional rubber growing districts in Sri Lanka. Major aims of the research were to explicitly model spatial relationships in adoption of fertiliser application in rubber cultivation and to identify the factors that influence them. Bayesian Spatial Autoregressive Probit (SARP) model was used in the study. The neighbours ' influence was measured in terms of a spatial correlation coefficient. Results revealed that the spatial correlation coefficient was positive and statistically significant, implying a strong influence by neighbours on a decision by a particular farmer. The results also highlighted the importance of socio economic factors and soil characteristics in adopting these practices.
Sarath Kumara P.H.,Lalan Rubbers Pvt Ltd. |
Warnajith Prasad A.K.D.,Rubber Research Institute of Sri Lanka |
Chandima Rohanadeepa V.,Rubber Research Institute of Sri Lanka
Journal of Rubber Research | Year: 2012
Low ammonia (LA) centrifugea latex of higher volatile fatty acid (VFA) values was blended with that of lower values at different blend ratios. The most important latex characteristics of these blends, namely VFA number, KOH number and MST were tested over a period of time at regular intervals. It was found that centrifugea latex with different VFA values could be blended to obtain a predetermined intermediate VFA value in the final blend. VFA number in the blends as well as in the two unblended latex samples increased gradually after an induction period of 40-50 days. The rate of increase of VFA number was more pronounced in the blends containing higher proportions of high VFA centrifugea latex. A formula was proposed to estimate the VFA number of the final latex blend using the VFA numbers of the initial components of the latex blend. The same formula could be used to estimate the quantity of latex from each latex component to be blended to obtain a targeted VFA value in the final latex blend. After an initial high rate of increase of KOH number in the blends prepared from fresh latex, the rate of increase reduced drastically to almost zero with the increase of maturity. The development of mechanical stability time (MST) of the blends over time was observed to be at par with the development of KOH number barring few exceptions.
Siriwardena S.,Universiti Sains Malaysia |
Siriwardena S.,Rubber Research Institute of Sri Lanka |
Ismail H.,Universiti Sains Malaysia |
Ishiaku U.,Universiti Sains Malaysia
Polymer International | Year: 2011
White rice husk ash (WRHA) and silica filled ethylene-propylene-diene terpolymer (EPDM) vulcanizates were prepared using a laboratory size two-roll mill. Curing characteristics and physical properties of vulcanizates were studied with respect to the filler loading and filler type. Filler loading was varied from 0-50 parts per hundred resin (phr) at 10phr intervals. Curing was carried out using a semi-efficient vulcanization system in a Monsanto rheometer. Enhancement of the curing rate was observed with increasing WRHA loading, whereas the opposite trend was observed for silica-filled vulcanizates. It was also indicated by the maximum torque and Mooney viscosity results that WRHA offers processing advantages over silica. Compared to the silica-filled vulcanizates, the effect of filler loading on the physical properties of WRHA-filled vulcanizates was not significant. According to these observations, WRHA could be used as a diluent filler for EPDM rubber, while silica can be used as a reinforcing filler. © 2001 Society of Chemical Industry.
Galpaya D.,Rubber Research Institute of Sri Lanka |
Ismail H.,Universiti Sains Malaysia |
Ahmad Z.,Universiti Sains Malaysia
Polymer - Plastics Technology and Engineering | Year: 2010
Polypropylene-grafted maleic anhydride (PP-g-MA) was used to enhance the compatibility of polypropylene (PP) and recycled acrylonitrile butadiene rubber (rNBR) blends. The blends were prepared by melt mixing using a Haake Rheomix Polydrive R 600/610 mixer at 180°C. The processing torque was used to investigate the mixing process. The better mixing of compatibilized blends (PP/rNBRMA) was evidence by the higher stabilization torque. Compared to uncomapatibilized PP/rNBR blends, tensile properties and oil resistance of compatibilized PP/rNBR were improved. SEM micrographs of tensile fractured surfaces showed better dispersion and better interfacial adhesion between the phases of compatibilized blends compared to uncompatibilized counterparts. © Taylor & Francis Group, LLC.
Fernando T.H.P.S.,Rubber Research Institute of Sri Lanka |
Jayasinghe C.K.,Rubber Research Institute of Sri Lanka |
Wijesundera R.L.C,University of Colombo |
Siriwardana D.,Rubber Research Institute of Sri Lanka
Journal of Plant Diseases and Protection | Year: 2010
Quality planting material is a basic requirement for the increase in productivity levels and one of the key indicators of quality is the health of nursery plants. Corynespora leaf fall disease (CLFD) affects all clones of rubber under nursery condition. In this investigation the most effective treatment to manage CLFD in nurseries was the introduction of overhead shading together with application of the fungicide mancozeb. The fungicide mixture (carbendazim + mancozeb) applied at 7-d intervals, and carbendazim sprayed at 2-week intervals together with shade showed equally good results. Carbendazim (0.5 g l-1 sprayed at 7- or 10-d intervals, the application of other fungicides, manco-zeb, metalaxyl 8% + mancozeb 64%, captan and propineb, at 3 g l-1 at 7-d intervals was also effective. Though the systemic fungicide, carbendazim efficiently controlled the disease, tebu-conazole and hexaconazole were found to be much less effective.
Jayasuriya M.M.,Rubber Research Institute of Sri Lanka |
Hourston D.J.,Loughborough University
Journal of Applied Polymer Science | Year: 2012
The effects of the PMMA content and the cross-linker level in the poly(methylmethacrylate) component on the dynamic and physico-mechanical properties of semi-2 interpenetrating polymer networks based on natural rubber and poly(methylmethacrylate) were determined. The miscibility of the components in these semi-2 interpenetrating polymer networks was determined using the loss tangent data, obtained from dynamic mechanical thermal analysis and the interphase contents were calculated from modulated scanning calorimetric data. Some component mixing in these semi-2 interpenetrating polymer networks was evident from these modulated differential scanning calorimetric and dynamic mechanical thermal analysis data. The degree of component mixing increased with cross-linker level in the PMMA phase. The PMMA content in the semi-2 IPNs has a significant effect on the tensile and hysteresis behavior of these semi-2 interpenetrating polymer networks. © 2011 Wiley Periodicals, Inc.
De Silva K.K.G.,University of Auckland |
Taylor M.P.,University of Auckland |
Nilmini R.,Rubber Research Institute of Sri Lanka |
Kariyawasm S.,SRI International |
Vithanachchi J.,SRI International
Advanced Materials - TechConnect Briefs 2016 | Year: 2016
Environmentally friendly, sustainable Natural Rubber (NR) based pylons that fulfil all the requirements of flexible pylons for harness horse racing tracks have been developed and commercialized. NR's inherent properties such as good resilience, impact resistance, flexibility and excellent overall performance has made it the ideal choice for this application. Use of non-leaching bio-based polymeric antioxidants have further increased the performance of rubber pylons. Cure characteristics, retention of mechanical properties after ageing at elevated temperatures and their non-staining properties are discussed. The development of rubber pylons has replaced the highly plasticized PVC pylons that become brittle in service losing its integrity due to plasticizer migration. The Product Accelerator (PA) model of engagement through local and international technology partners, industry partners and service providers has made it possible to take rubber pylons rapidly in to the global markets.