Temperature dependence analysis of mechanical properties and bending behaviors of shape memory programmable composites

Abstract

Temperature significantly affects the mechanical properties of shape memory polymers (SMPs). The temperature dependence of mechanical properties and bending behaviors of shape memory polymer composites (SMPCs) was investigated in this study. Dynamic mechanical analysis and static mechanical tests were performed to investigate the temperature dependence on the mechanical properties of SMP and SMPC. The tensile strength and shear strength of SMP declined as the temperature rose, while the elongation at break increased first and subsequently reduced. SMPC exhibited brittle fracture at low temperatures and fiber buckling at high temperatures, respectively. Subsequently, a temperature-dependent model of the bending behavior of SMPC was developed. Theoretical model revealed the effect of temperature and fiber volume content on fiber buckling. The higher the temperature and fiber volume content is, the easier the fiber buckles. The effects of temperature, thickness and fiber volume content on critical buckling curvature, strain energy, half-wavelength and amplitude were investigated. Temperature and fiber volume content were positively related to critical buckling curvature, strain energy and amplitude, but negatively related to half-wavelength. Thickness was positively related to strain energy, half-wavelength and amplitude, but negatively correlated to critical buckling curvature, in which thickness does not determine whether SMPC buckling occurs. Eventually, the theoretical model was verified using the four-point bending test to ensure its credibility. The research results are expected to provide theoretical guidance for the design and application of SMPC.