The trans-gauche state transformation commonly exists in polymers. However, the fundamental understanding of the roles of kink (gauche state) on the thermal energy transport in polymer chains is rather limited. From atomic simulations, we show that kinks greatly scatter phonons in single polyethylene chains, and even a single kink can reflect more than half of the phonons. Further studies show that kinks not only add extra thermal resistance to the chain but also break the whole chain into small segments and each with reduced thermal conductivity. A simple series thermal resistance model is proposed to estimate the effective thermal conductivity of single polymer chains with multiple kinks.

Generally, the electrical properties of nanocomposite are affected by the type, size, filling concentration and surface treatment process of the nanoparticle. In this study, nanocomposites of polyethylene (PE) with varying filling contents of nano‐alumina particles were prepared by the melting blending method and three different kinds of coupling agents were applied for surface modification properties of the nanoparticles. Two of them were silane based and the other was titanate based. The effect of different coupling agents on the dielectric properties was studied. Fourier‐transform infrared spectroscopy and thermo‐gravimetric analysis were used to verify their compositions. Scanning electron microscope and polarised optical microscopy were used for morphology study. Dielectric permittivity, direct current (DC) volume resistivity and DC breakdown strength characterised their improved insulation performance with nano‐alumina as filler. Thermal stimulated current results revealed that adding nano‐alumina particles into low‐density PE could provide more deep traps and increase DC resistivity.

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