Browsing by Author "Sudusinghe, Y.C.Y."

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    A Novel Method to Manufacture Skim Crepe Rubber with Low Nitrogen Content using Pineapple Juice Treated Skim Latex
    (Uva Wellassa University of Sri Lanka, 2019-02) De Zoysa, D.M.D.A.; Senevirathne, A.M.W. K.; Wijesinghe, H.G.I.M.; Sudusinghe, Y.C.Y.; Siriwadena, S.
    Skim Natural Rubber Latex (SNRL) is a by-product obtained during the manufacture of centrifuged latex, contains low dry rubber content (<5%). Direct coagulation of SNRL with concentrated sulfuric acid is the conventional method used to manufacture Skim Crepe Rubber (SCR). SCR fetches a low market value due to its inferiority in quality inherited by the presence of higher non-rubber content compared to that in other raw rubber types. This study focused to develop a healthier and environmental friendly manufacturing process for SCR with lower nitrogen content and higher quality through removal of protein. Pineapple juice (PAJ) was initially treated with Potassium oleate before it was mixed with SNRL (15 ml of PAJ was added to 1 L of SNRL) and kept for 48 hrs at room temperature (28 oC). Then a creaming agent was added at 25 phr to PAJ treated SNRL after adjusting pH to 7.5 and creamed for 36 hours. Three different acidic coagulants of 20% (w/w): sulfuric, oxalic and formic acid were employed to coagulate deproteinized creamed fraction. The control sample of SCR was also prepared by adding 20% (w/w) sulfuric acid to fresh SNRL. Raw rubber properties were evaluated according to the ISO standards. All SCR samples prepared by using creaming followed by the PAJ treatment have low nitrogen content (0.300.40% w/w) and Mooney viscosity (7590 MU) along with higher ash content (0.4-0.5% w/w) than the control sample where above parameters were 1.44% (w/w), 91.55 MU and 0.17% (w/w) respectively. It was found that total acid requirement could be reduced by 50% using novel method. Also deproteinized SCR manufactured using oxalic acid as the coagulant has highest Plasticity Retention Index (61.17%) with good initial Plasticity. This method might be a good solution for removal of protein substances and unfavourable metal ions from SNRL enhancing the quality of SCR. Therefore, this novel method would allow to obtain a better competitive commercial value for SCR.
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    A Novel Process to Manufacture Low Protein Contained Centrifuged Latex
    (Uva Wellassa University of Sri Lanka, 2020) Hansani, P.M.G.S.; Sudusinghe, Y.C.Y.; Senevirathna, A.M.W.K.; Lochana, E.A.L.; Sandamali, P.K.N.N.
    Removal of protein in Natural Rubber (NR) latex has been a focus of great importance as some users face serious allergy issues when they exposure to NR latex-based products. Therefore, in this study, an attempt was taken to develop a commercially viable and environmentally friendly hybrid route by combining fractionation and creaming processes, to manufacture quality centrifuged latex with reduced protein level. Firstly, preserved NR field latex was fractionated at four different Dry Rubber Content (DRC) levels: 15%, 18%, 21%, and 24%. Subsequently, all fractionated and diluted field latex samples at 10% DRC were creamed up to 30% DRC using sodium alginate at 20 phr concentration. Creamed latex obtained were then subjected to the centrifugation process. Fractionated Creamed Centrifuged Latex (FCCL) samples were compounded according to the basic formula and cured in a drying oven at 120 ℃ for 20 minutes. Latex properties and their film properties were studied according to the standard test procedures and compared with Single Centrifuged Latex (SCL) and Double Centrifuged Latex (DCL). The FCCL sample fractionated at 15% DRC (15% FCCL) showed the lowest nitrogen content than other centrifuged samples while other samples follow the order of 18% FCCL< 21% FCCL < 24% FCCL