Co-authors​ :

 Tejas TEJAS PRAMOD NAIK (UNITED KINGDOM), Inderdeep SINGH , Apurbba APURBBA KUMAR SHARMA , Hana HANA YU  

Conventional manufacturing procedures commonly employed for natural fibre reinforced thermoplastic composites (NFRCs), such as sisal/high-density polyethylene (HDPE) composites, encompass compression moulding, injection moulding, or vacuum bagging processes. In recent times, there has been a growing interest in exploring innovative manufacturing methods that are energy-efficient, environmentally friendly, and time-saving. Microwave energy has, therefore, gained attention for its time and energy efficiency, along with its environmentally friendly approach to processing polymer matrix composites. The recent introduction of the novel microwave-assisted molding (MAM) method enables the fabrication of NFRCs, offering benefits like a rapid heating rate and volumetric heating, contributing to enhanced interfacial bonding performance, as demonstrated in the authors' previous work [1]. In this context, therefore, to continue benefiting from sisal/HDPE composites fabricated using the MAM method and to investigate their potential suitability for use in structural applications exposed to outdoor or wet environments, the wetting, absorption, and degrading behaviour of 10 wt.% sisal/HDPE composite were examined in various environmental conditions. Different environments, including tap water, sodium hydroxide (NaOH) solution (5%), and vegetable oil, were utilised. Absorption behaviour of the developed composites is thoroughly addressed for all environments and is supported by surface morphology analysis. The study also explored the mechanical properties and their relationship with various characteristics, such as thickness swelling, liquid absorption, and morphology. The investigation revealed that the degradation in interfacial bonding between fibres and matrix led to a decrease in hardness, tensile, and flexural properties. The water environment resulted in the maximum liquid absorption and thickness swelling, whereas vegetable oil had the minimum. Composites conditioned in a NaOH solution (5%), compared to those conditioned in other environments, exhibited the highest level of property degradation. The study suggests the potential use of sisal/HDPE composites for structural applications with moderate loads in environments that are both chemically neutral and viscous, such as a storage tank for storing oil (viscous liquid).