Visco-elastic properties of OMMT filled fractioned bleached crepe rubber

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dc.contributor.authorWijesinghe, H.G.I.M.
dc.contributor.authorAlakolanga, A.G.A.W.
dc.contributor.authorWithanage, N.S.
dc.contributor.authorRatnayake, U.N.
dc.date.accessioned2022-02-09T10:52:51Z
dc.date.available2022-02-09T10:52:51Z
dc.date.issued2015
dc.description.abstractNatural Rubber (NR) latex tapped from Hevea brasiliensis converts into an important engineering material for different applications. NR latex pale crepe, the purest form of NR produced by Sri Lanka, is mainly used in pharmaceutical and surgical applications, infant toys, food contact rubber articles and adhesives, (Senevirthne and Kumara, 2003). Natural Rubber has a higher greenstrength as but it is soft and has lower dimension stability (Cohan and Spielman, 1948) which is one of the major draw backs in NR for engineering application. Recently, Nanoclays such as montmorillonite clay are attracted as an alternative filler to achieve the reinforcement of rubber compounds by replacing conventional fillers (Ratnayake and Peiris, 2010). Study the effect of Organo-montmorillonite (OMMT) on the visco elastic properties of fractioned bleached crepe rubber will helpful for the advancement of the raw rubber industry as value addition. In this study, OMMT dispersion in the rubber matrix has studied not only by Mooney viscosity and stress relaxation properties but also by the physical properties of vulcanizates. Therefore this study may help to have an advantage for the development of crepe rubber industry and product manufacturing industry in Sri Lanka. Material and Methods NR field latex was obtained from NR processing factory at Rubber Research Institute, Dartonfield, Agalawaththe. Montmorillonite clay modified with quaternary alkyl ammonium salt (OMMT)was used as the nanofiller. Other general chemicals and laboratory equipment were obtained from Rubber Research Institute, Rathmalana. Initially, 5%(w/w) aqueous dispersion of OMMT was prepared using a surface active agent as a dispersing agent. Latex mixing/intercalation method(Gatos and Kocsis, 2010) was carried out to prepare OMMT filled fractioned bleached crepe rubber (OFBCR). Dry rubber content (DRC) of fractionated bleached latex was diluted up to 10% and subsequently OMMT dispersion was incorporated to latex samples at OMMTloading from 0 to 8 phr with an interval of 2 phr, with simultaneous stirring.Standard latex crepe manufacturing procedure was adopted to prepare OFBCR (Senevirthne and Kumara, 2003). Laces were dried in the drying tower at 34°C for three days. Complete randomized design was applied to assign treatments, T 0(0 phr), T2 (2 phr), T4 (4 phr), T6 (6 phr) and T8 (8 phr). The NR was characterized based on DRC and the OMMT was characterized by the ash content. Money viscosity and stress relaxation of OFBCRs were measured according to the [ISO/R 289- 1963] by the Ektron Mooney viscometer. Then the OFBCR samples were compounded according to the pre-determined formulation. Curing characteristics of the OFBCR samples were measured by using MDR 2000 (moving die rheometer, M/S Alpha Technologies, USA) at 150°C according to the ISO 3417:2008 procedure. OFBCR samples were moulded by hydraulic hot press at 150°C temperature and 20MPa pressure for optimum cure time derived from the cure characteristics data.The tensile properties of OFBCR samples were determined by “Instron 3300 Series” material testing machine at a crosshead speed of 500 mm/min as per ISO 37:2011. The hardness of the samples were determined using Elastocon bares digi hardness tester according to the ISO 48:2010. Compression set at constant strain was measured according to ISO 815-1:2008 test method andtear strength of OFBCR samples were determined by “Instron 3300 Series” material testing machine at a crosshead speed of 500 mm/min according to ISO 34- 1:2011. All tests were carried out at 27±2°C and each test was replicated at least 3 times. Data were analyzed by using the Minitab 16 statistical software with the use of General Liner Model (GLM) with Tukey’s all pair wise comparison tests at 95% confidence interval. Results and Discussion Field latex used for the preparation of nano crepe rubber showed the dry rubber content of 30%. OMMT clay has modified with quaternary alkyl ammonium salts. The ignition weight loss of OMMT is 43%–48%. Ash content of clay is 52%-58%. This ash content represents the amount of silicates and other inorganic metal amount in the clay. Ignition weight loss is correlated to the amount of quaternary ammonium alkyl modifier and adsorbed moisture amount in the clay. Mooney viscometer is an instrument to measure the 'stiffness' of uncured compounds, the result of that viscosity is called as Mooney viscosity at ML 1+4 (100°C). Mooney stress relaxation coefficient is the slope of the power law model when it is in logarithmic scale (log M = a(log t) + log k) where M- torque units from the Mooney stress relaxation test, k- a constant equal to torque 1 s after the rotor has stopped, ‘a’- an exponent that measures the rate of stress relaxation and t- testing time. Also elasticity of rubber material is inversely proportionate to the ‘a’andlower elasticity improves the mixing of rubber and processing, especially extrusion and calendaring. Malac J., (2009). Clay loading level (phr) has significantly affected to the Mooney viscosity expressed as ML (1+4) 100°C of OFBCR samples (p-0.000). Only T6 and T8 has not indicated a significant difference (p-0.0569) between them with respect the Mooney viscosity but all other treatment levels are significantly different among (p-0.000). Mooney viscosities for T0, T2, T4, T6 and T8 are presented in Figure 1. The reason for the reduction of Mooney viscosity is, when increasing the OMMT loading, the plasticization of rubber material by OMMT and may possibly be the chain slippage over the clay platelets (Kader et al., 2010). As reported in Figure 2, the stress relaxation coefficient has increased up to 4 phr and there after it reduces. The maximum stress relaxation coefficient has indicated at the 4 phr clay loading level, therefore, it can be concluded that OFBCR with 4 phr OMMT clay loading has a better processability than other samples. Long relaxation times and high amplitudes of stress relaxation suggest the mechanism of structural relaxation involving large-scale displacements of isolated clusters of nanoparticles within the rubber matrix and vice versa (Dick, 2010).en_US
dc.identifier.isbn9789550481088
dc.identifier.urihttp://www.erepo.lib.uwu.ac.lk/bitstream/handle/123456789/8328/26-PLT-Visco-elastic%20properties%20of%20OMMT%20filled%20fractioned%20bleached%20.pdf?sequence=1&isAllowed=y
dc.language.isoenen_US
dc.publisherUva Wellassa University of Sri Lankaen_US
dc.subjectAgricultureen_US
dc.subjectExport Agricultureen_US
dc.subjectCrop Productionen_US
dc.subjectRubber Technologyen_US
dc.subjectRubber Productionen_US
dc.subjectNatural Rubberen_US
dc.titleVisco-elastic properties of OMMT filled fractioned bleached crepe rubberen_US
dc.title.alternativeResearch Symposium 2015en_US
dc.typeOtheren_US
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