The structure, properties, and kinetics of thermal oxidation of blends based on polyhydroxybutyrate (PHB) and ethylene propylene rubber (EPR) were studied. The physicomechanical properties were studied using a ZE-40 tensile testing machine (Germany), and the crystallisation temperature Tcr and melting temperature Tm of PHB in the blends were determined on a DSM-2M differential scanning calorimeter at a scanning rate of 16°C/min. The morphology of films was determined by scanning electron microscopy on a Hitachi S-570 microscope (Japan). The kinetics of thermal oxidation of the blends was assessed according to the amount of absorbed oxygen. With increase in the PHB content in the blend there is a reduction in the elongation at break and an increase in the tensile strength and modulus. Change in the PHB content and in the oxidation time leads to negligible changes in Tcr and Tm. It was established that the greatest reactivity of blends in relation to oxygen is observed in the range of PHB concentrations of 20–40%, where the greatest phase interface area is formed. It was shown that, by changing the ratios of EPR and PHB, it is possible to control the kinetics of thermal oxidation of the blends. It was shown that, in the range of concentrations of 50–70% PHB, phase inversion occurs in the blends.
A quick method for assessing elastomer-to-shungite bond strength is presented. An Instron 3365 tensile testing machine was used to measure the force needed to peel away a cotton strip impregnated with a rubber solution in CCl4 from the surface of shungite sheets. The rubbers included butyl rubber (BR), nitrile butadiene rubber (SKN-18), polyisoprene (SKI-3), a copolymer of ethylene and vinyl acetate (CEVA), polychloroprene (PC), chlorosulphonated polyethylene (CSPE), and chlorinated butyl rubber (CBR). The nature of the obtained results depends on elastomer functionality. Smooth curves of the dependence of the measured stress on the distance between the clamps of the tensile testing machine were obtained for elastomers not having functional groups interacting with the shungite, e.g. for BR; on the curves for elastomers interacting with the shungite, e.g. for PC, a series of peaks was observed on the curves. The obtained results make it possible to predict the strength of elastomer composite materials containing shungite.
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