Browsing by Author "Chandramali, T.H.D.S."

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    Preparation and Characterization of Deproteinized Crepe Rubber using a Serin Type Proteolytic Enzyme
    (Uva Wellassa University of Sri Lanka, 2020) Chandramali, T.H.D.S.; Sudusingha, Y.C.Y.; Siriwardena, S.; Lochana, E.A.L.; Senevirathna, A.M.W.K.
    A serin type Proteolytic Enzyme (PE) was used as a substitute for traditionally used papain which has no reliable supply at present in the local market, for the manufacture of Deproteinized Crepe Rubber (DPCR). Field latex was coagulated by different PE dosages varying from 1 to 4 ml with 1 ml intervals per litre of the diluted field latex at 10% DRC and matured for 72 hours. The control sample was coagulated within 24 hours using 1% formic acid and all coagula were converted into pale crepe form. The impact of the maturation period (24-72 hours) on raw rubber properties was also studied using the selected sample which meets the lowest Nitrogen Content (NC) among all the candidate samples. Raw rubber properties, curing characteristics, and physicomechanical properties of all the vulcanizates were studied. All enzyme-treated samples showed lower NC (0.10- 0.14%w/w) than the control (0.31%w/w). It was noticed that the increase of PE volume and maturation period reduced the NC in the samples. Raw rubber properties of the enzyme-treated samples with a 72-hour maturation period have complied with the required specifications of DPCR except for the Plastic Retention Index (PRI). It was found a reduction of PRI and ash content while increasing in Po values with the increment of PE dosage and maturation period. However, the enzyme treatment (4ml/liter) with a 24-hour maturation period was able to achieve the slightly higher PRI value (63.3%) than the recommended value (60%) for both control and DPNR. It was found that curing time (T90) of the control sample was higher than the enzyme-treated samples and the control sample showed better tensile strength than the enzyme-treated samples due to the protein reinforcement effect and higher crosslink density. Overall, it could be concluded that the selected enzyme has the potential to use it for manufacturing DPCR. Keywords: Deproteinized crepe rubber, Nitrogen Content, Maturation period, Raw rubber properties
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    A Study on the Potential of Using Savinase in Manufacture of Deprotenized Crepe Rubber
    (Uva Wellassa University of Sri Lanka, 2015) Chandramali, T.H.D.S.
    Deproteinized Crepe Rubber (DPCR), purified form of Natural Rubber (NR) with low Nitrogen Content (NC) has high demand in the global market due to its superior properties and quality consistency than conventional crepe rubber. Enzymatic hydrolysis of protein present in NR has commonly used technique in commercial-scale to manufacture DPCR. However, DPCR has not been produced, presently, due to the scarcity of suitable proteolytic enzymes and cost in the local market. Savinase is widely used and commercially available enzyme to remove protein especially in food and textiles industries. Therefore, this study was carried out to study the potential of Savinase in the manufacture of DPCR. DPCR samples were coagulated by varying Savinase dosage from 1 to 4 ml with 1 ml interval per 1 litre of the diluted field latex with 10% DRC and 1% formic was used to coagulate the control sample. After 3 days, enzymatic and acid coagulated samples were converted into pale crepe using standard pale crepe rubber manufacture procedure. Impact of the maturation time (1-3 days) on raw rubber properties were studied using the sample containing 4 ml Savinase in 1L of diluted latex. Raw rubber properties, curing characteristics and physico-mechanical properties of vulcanizates were also evaluated according to the ISO standards. Based on the NC, the amount of protein in the samples was used to interpret. All Savinase treated samples have shown lower NC (0.10-0.14 w/w %) than the control (0.31 w/w %). Further Increase of Savinase volume and the maturation period reduce the NC in the samples while increasing NC, COD and BOD in the serum. Other raw rubber properties of Savinase treated samples with 72 hour maturation period are compiled with the required specification for DPCR already established, excluding Plastic Retention Index (PRI). The Savinase treatment (4m1/litre) with 24 hours maturation period showed comparable PRI value (63.3%) with the control while other raw rubber properties are within the specification of DPNR. Moreover, reduction in NC, PRI and ash content while Po value increment was observed with increasing maturation time. Due to the protein reinforcement effect and higher crosslink density, the control sample showed better tensile strength than the STC samples. Other physio- mechanical properties of Savinase treated samples were comparable with the control. Overall, it can be concluded that the Savinase enzyme has a potential to use for manufacturing DPCR. Keywords: Deproteinized Crepe Rubber, Natural Rubber, Nitrogen Content, Raw rubber properties