Potential application of betel nut husk fibre/phenolic hollow microsphere filled vinyl ester composites as thermal insulation panels in roof attic

Abstract

Betel nut husk (BNH) fibres obtained from a local betel nut plantation was used as a low-cost filler to produce vinyl ester (VE) matrix composites with thermal insulating properties. The composite was prepared using 10 wt.% BNH fibre and 5 wt.% phenolic hollow microspheres (PHMS) fillers by casting process. A pilot-scale model resembling common building with a roofing system was built to investigate the effect of thermal insulation provided by the 10 wt.% BNH/5 wt.% PHMS/VE composites panels installed in the roof system. Two models were built to study the temperature reduction in the attic part, when the thermal insulation panels made of 10 wt.% BNH/5 wt.% PHMS/VE composites was installed. A thermocouple type (K) range (-30°C to 110°C) was used to determine the temperature of the roof attic model by attaching the thermocouple sensor on the attic surface under the roof part. The temperature observation was conducted in an open area on a hot sunny day, to expose the roof attic model to full solar radiation. The temperatures were measured hourly, from 7.00 am to 7.00 pm, and the temperature readings were recorded. It was observed that the attic with 10 wt.% BNH/5 wt.% PHMS/VE composites insulation panels showed a much lower temperature during the 12-hours sun exposure. The highest temperature of both insulated and non-insulated roof attic models was recorded around 2.00 to 4.00 pm, which corresponds to the increase in the outdoor temperature due to the sunlight exposure. The lowering of the attic temperature indicated that a good heat barrier mechanism had been achieved with the installation of the composites. The heat transfer from the outdoor environment to the interior parts of the building was restricted by the low thermal conductive air-filled porous structures of BNH fibres and hollow cavities inside the hollow microspheres filler in the 10 wt.% BNH/5 wt.% PHMS/VE composites.