At glass transition temperature, T g the rubber compound becomes stiff and brittle and it loses all its rubbery characteristics. This article deals with the changes in T g of rubber blends based on natural rubber and polybutadiene rubber of varying vinyl content having different types and content of plasticizers, different curing systems and its effect on physico-mechanical properties to improve its freezing resistance. The plasticizers used were dioctylphthalate (DOP), tricrecylphosphate (TCP), dioctyladipate (DOA), and oil type plasticizers like parafinic oil (P#2) and aromatic oil (A#2). Among the plasticizers, when DOP and DOA content was high, an appreciable decrease of T g was found compared to TCP. Moreover, there was a remarkable decrease of T g using DOA plasticizer, which shows more effective on freezing resistance. However, there was not much change in T g with oil-type plasticizers with high oil content compared to TCP plasticizer. The effect of cross-linking systems such as conventional sulfur vulcanization (CV), efficient sulfur vulcanization (EV), and dicumyl peroxide (DCP) and rubber blends with varying vinyl content in polybutadiene rubber were also carried out. It was found that T g in different cross-linking system decreased in this order: CV < EV < DCP. It reveals that DCP cross-linking system affect more for improving freezing resistance. Physico-mechanical properties such as tensile strength, tear strength, hardness were also measured. The ratio of initial slope (M 0 ) to steady-state slope (M 1 ), M 0 /M 1 in tensile curves of different blends were verified, which in turn related to the physico-mechanical properties and freezing resistance of rubber compounds. V C 2013 J. Appl. Polym. Sci. 2014, 131, 39795.
Proton exchange membrane (PEM) fuel cell stack requires gaskets and seals in each cell to keep the reactant gases within their respective regions. Gasket performance is integral to the successful long-term operation of a fuel cell stack. This review focuses on properties, performance and degradation mechanisms of the different polymer gasket materials used in PEM fuel cell under normal operating conditions. The different degradation mechanisms and their corresponding representative mitigation strategies are also presented here. Summary of various properties of elastomers and their advantages and disadvantages in fuel cell'environment are presented. By considering the level of chemical degradation, mechanical properties and cost effectiveness, it can be proposed that EPDM is one of the best choices for gasket material in PEM fuel cell. Finally, the challenges that remain in using rubber component as in PEM fuel cell, as well as the prospects for exploiting them in the future are discussed.
Expanded thermoplastic polyurethane (ETPU) beads were prepared by a supercritical CO2 foaming process and compression molded to manufacture foam sheets. The effect of the cell structure of the foamed beads on the properties of the foam sheets was studied. Higher foaming pressure resulted in a greater number of cells and thus, smaller cell size, while increasing the foaming temperature at a fixed pressure lowered the viscosity to result in fewer cells and a larger cell size, increasing the expansion ratio of the ETPU. Although the processing window in which the cell structure of the ETPU beads can be maintained was very limited compared to that of steam chest molding, compression molding of ETPU beads to produce foam sheets was possible by controlling the compression pressure and temperature to obtain sintering of the bead surfaces. Properties of the foam sheets are influenced by the expansion ratio of the beads and the increase in the expansion ratio increased the foam resilience, decreased the hardness, and increased the tensile strength and elongation at break.
Rubber blends based on ethylene-propylene-diene-monomer (EPDM) rubber and fluoroelastomer (FKM) having various blend ratios were prepared. The phase morphology, cure characteristics, hardness, tensile and dynamic viscoelastic properties of the blends were investigated. The cure rate of the blends increased, while the crosslink-density decreased as the FKM content increased. The hardness, tensile strength and elongation at break, and storage modulus (E') increased with increasing FKM loading. A typical incompatible blend behavior was found by observing two distinct tanδ peaks corresponding to EPDM and FKM. Based on the morphology investigation by scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS) analyses, a typical 'sea-island' phase morphology was observed for the EPDM/FKM blends. As the FKM loading was increased to 50 phr, the EPDM was found to remain as the continuous phase. At the 80 phr of FKM, a co-continuous phase was observed and the phase inversion was observed at 90 phr of FKM.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.