Browsing by Author "George, KE"

Now showing 1 - 3 of 3
  • Item
    Effect of partial replacement of di(2-ethyl hexyl)phthalate, by a polymeric plasticizer, on the permeability and leaching properties of poly(vinyl chloride)
    (JOURNAL OF APPLIED POLYMER SCIENCE, 2006) Sunny, MC; Ramesh, P; George, KE
    Acrylonitrile butadiene rubber (NBR) was used as a polymeric plasticizer in poly(vinyl chloride) (PVC) for the partial replacement of di(2-ethyl hexyl)phthalate (DEHP). The effect of this partial replacement on DEHP leaching from the PVC was evaluated at 10, 25, and 40 degrees C. The study shows that the incorporation of NBR reduces the rate of DEHP leaching, the reduction being prominent at lower temperatures. Gas permeability of the NBR-modified samples was also evaluated at the above temperatures using oxygen and carbon dioxide. A reduction in gas permeability is observed in NBR-modified samples compared to the PVC plasticized with DEHP alone particularly in the case of carbon dioxide. Water vapor transmission rates of the NBR-modified samples are higher than that of the control sample. The NBR-modified PVC sample was found to be noncytotoxic in the in vitro cytotoxic evaluation both by direct contact and test on extract methods. (c) 2006 Wiley Periodicals, Inc.
  • Item
    Metallocene based polyolefin: a potential candidate for the replacement of flexible poly (vinyl chloride) in the medical field
    (POLYMERS FOR ADVANCED TECHNOLOGIES, 2010) Sunny, MC; Ramesh, P; Mohanan, PV; George, KE
    A comparative assessment of the performance properties of metallocene polyolefin (m-PO) with those of plasticized poly (vinyl chloride) (pPVC) and ethylene vinyl acetate (EVA) copolymer having 18% vinyl acetate content (EVA-18), the two common polymers used for flexible medical products, is carried out. The preliminary evaluation of the processability, mechanical properties, and thermal stability of the new material, m-PO is described. The processability parameters like mixing torque and melt viscosity of m-PO are found to be comparable with those of pPVC and EVA-18. Mechanical properties such as tensile strength, elongation at break, and tear strength (TS) of m-PO are much higher than that of pPVC and EVA-18. Thermo gravimetric analysis (TGA) indicates that the thermal degradation of m-PO takes place only at temperatures above 340 degrees C and can be processed at 170 degrees C without much damage. Oxygen and carbon dioxide permeabilities of m-PO at three different temperatures (10, 25, and 40 degrees C) are evaluated and compared with those of pPVC and EVA-18. It could be seen that the permeabilities of both the gases for m-PO at three temperatures were lower than those of pPVC and EVA. Biological evaluation of m-PO is carried out by assessing its cytotoxicity, hemolytic property, and blood clotting initiation. The cytotoxicity studies indicate that m-PO is non-toxic to the monolayer of L929 mammalian fibroblast cell lines on direct contact or the exposure of its extract. Non-hemolytic property of m-PO by direct contact as well as test on extract is revealed both in static and in dynamic conditions. Blood clotting time experiments indicate that the initiation of blood clotting due to m-PO is faster than that of pPVC and EVA-18. Copyright (C) 2009 John Wiley & Sons, Ltd.
  • Item
    Use of polymeric plasticizers in polyvinyl chloride to reduce conventional plasticizer migration for critical applications
    (JOURNAL OF ELASTOMERS AND PLASTICS, 2004) Sunny, MC; Ramesh, P; George, KE
    Di-(2-ethyl hexyl) plithalate (DEHP), a conventional plasticizer in polyvinyl chloride (PVC), was partially replaced by polymeric plasticizers. Three different elastomers such as nitrile rubber (NBR), carboxylated nitrile rubber (XNBR) and epoxidized natural rubber (ENR) were used as polymeric plasticizers. Mechanical properties and leaching of DEHP of the modified PVC in comparison to the compound containing DEHP alone were investigated. The study shows that the migration of the DEHP can be reduced significantly without affecting the useful mechanical properties.