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Abstract. The studies of electrical properties of the polyisoprene (PI) matrix/high structure carbon black (HSCB) composites (PCBC) with various concentrations (8, 9, 10 and 11 mass parts) of filler have been carried out in the temperature interval of 90K-330K. In this paper we focus on the investigation of direct current (DC) conductivity in a low-temperature region with negative temperature coefficient of resistivity (NTCR). It has been proven that variable range hopping (VRH) conduction is dominated by hopping of carriers among localized states in a low-temperature range. At higher temperatures the nearest neighbour hopping (NNH) conductivity or constant range hopping charge transport takes place. The reversibility as well as small hysteresis of resistance change versus temperature indicates prospective temperature sensor application for PCBC.

In this paper validation of experimental and numerical results of low-velocity impact tests of unsaturated polyester/glass fibre composite laminate has been carried out. Impact response of composite laminates was experimentally studied with drop-tower Instron 9250HV determining impact force, energy absorption and deflection. In addition, quasi-static testing equipment Zwick Z100 has been used to determine material mechanical properties to ensure good input data for numerical predictions. Numerical model has been created with the finite element commercial code ANSYS/LS-DYNA to simulate impact response of composite laminate. Also non-destructive ultrasonic B- and C- scan imagining with USPC 3010 system has been used to identify the deformation regions in the specimens and compare to simulation results. During the impact test all samples were perforated, showing brittle response followed by matrix cracking and delamination. Overall good agreement between experimental and simulation results was achieved, comparing impact characterizing parameters as load, energy and deflection. Discrepancy has been observed between ultrasonic scanning and simulation code ANSYS/LS-DYNA results of rupture and delamination. Simulation shows less uniform and larger deformation than it was experimentally observed.

http://dx.doi.org/10.5755/j01.ms.17.4.773

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