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Natural rubber with low heat generation was prepared by the inclusion of boron carbide (B 4 C). Tensile testing, scanning electron microscopy (SEM), dynamic mechanical analysis, and thermal constant analysis were performed. The results show that a slight deterioration of tensile strength only occurred at a high volume content (>20 vol %). The thermal conductivity increased for the formation of well-maintained B 4 C thermal conductive pathways. SEM images and theoretical analysis demonstrated that the specific area of B 4 C was small and the interfacial activity was low. Infrared thermal images taken by the infrared camera proved the low heat generation of the composites, which originated from the high thermal conductivity and the weak interface.

Vulcanized natural rubber (NR) under quiescent thermal oxidation aging and high temperature fatigue loading with small strain amplitude was investigated by the infrared spectroscopy, scanning electron microscopy, and positron annihilation lifetime spectroscopy measurements. IR results demonstrated the thermal oxidation degradation process of vulcanized NR at 85 C. During high temperature fatigue loading, nanoscale cracks and voids that are generated by the combined impact of thermal oxidation and cyclic loading were detected. Further investigation suggests that the nucleation effect of dissolved vapor and gas in the low molecular weight domains of the NR under fatigue loading accounts for the appearance of nanocracks. This work provides some new insight into the crack initiation mechanism of NR during high temperature fatigue loading, which has not been clearly understood.

Abstract. energy conservation and emission reduction is an extremely important task to be fulfilled by our country [1] . As a big energy consumer of the building industry, the energy consumption of the building industry covers 40%-50% of the social total energy consumption. Since China is in urgent need of energy, the application of energy conservation and emission reduction technology is of great significance for relieving the energy tension, so it is a pressing task for the building industry to study new wall materials [2] .This paper carries out a contrastive analysis of three wall materials which are most widely used in our county.