Boron nitride and hyperbranched polyamide assembled recyclable polyisoprene vitrimer with robust mechanical properties, high thermal conductivity and remoldability

Effect of different fillers on thermal conductivity, tribological properties of Polyamide 6

An influence of different filler types and filler content on the thermal and abrasive wear properties of polyamide-6 is investigated. Al₂O₃, MgO, two glass powders with different SiO₂ contents, and natural zeolite powder were selected as fillers. The fillers individually were added to the polymer matrix in proportions of 50 and 70% by weight. A hybrid filler-containing composite was created by mixing PA6/70 wt% MgO and PA6/80 wt% zeolite. The results show that the thermal conductive enhancement factor is highest for PA6/70 wt% Al₂O₃ (145%) and PA6/hybrid fillers 75 wt% (92%). The Lewis-Nielsen and Reciprocity models agreed with the measured data with less than 26% deviation, except for the MgO-loaded composites. In the case of a hybrid composite, the additive model proves to be a good approximation. The abrasive effect of the different fillers was characterised by the volume loss of the steel pin using the pin-on-disc method. A new parameter is developed that considers the thermal conductivity enhancing effect of the fillers and their abrasive effect. In addition to ceramic fillers, aluminium-hydro-silicate, e.g. natural zeolite, and their mixtures offer new opportunities for the development of thermally conductive composites, as they are more economical to use in manufacturing processes.

hBN Flake Embedded Al2O3 Thin Film for Flexible Moisture Barrier

Due to the vulnerability of organic optoelectronic devices to moisture and oxygen, thin-film moisture barriers have played a critical role in improving the lifetime of the devices. Here, we propose a hexagonal boron nitride (hBN) embedded Al2O3 thin film as a flexible moisture barrier. After layer-by-layer (LBL) staking of polymer and hBN flake composite layer, Al2O3 was deposited on the nano-laminate template by spatial plasma atomic layer deposition (PEALD). Because the hBN flakes in Al2O3 thin film increase the diffusion path of moisture, the composite layer has a low water vapor transmission ratio (WVTR) value of 1.8 × 10-4 g/m2 day. Furthermore, as embedded hBN flakes restrict crack propagation, the composite film exhibits high mechanical stability in repeated 3 mm bending radius fatigue tests.