Green and sustainable kapok fibre as novel core materials for vacuum insulations panels.

• The kapok fiber VIP was green, degradable and nonpetroleum-based. • Hollow structure and porosity of fibres retained in wet forming process. • The thermal conductivity of kapok fiber VIP was as lower as 6.12 mW/(m·K). • Thermal conductivity of VIPs insensitive to temperature change. Vacuum insulation panel (VIP) is a new type of thermal insulation material with ultra-low thermal conductivity. Most of the VIP core materials are petroleum based, which helps achieve good thermal insulation performance and long service life. However, high cost and poor sustainability are not conducive to the long-term development of this industry. In this study, a new strategy is developed to prepare VIP core materials by using light, eco-friendly, and renewable kapok fibres. The results show that the wet forming process of the kapok fibre core material can maintain their hollow structure of the fibre and the porosity of VIP core could reach above 94%. The prepared kapok fibre VIPs have excellent thermal insulation performance and the thermal conductivity was as lower as 6.12 mW/(m·K) at an internal pressure of 0.05 Pa. Furthermore, these VIPs have outstanding stable thermal performance, and thermal conductivity increased only by 9–13% when the ambient temperature increased from 15 to 55 °C. The VIP density is lower than 105 kg/m3 due to the special thin-walled and large cavity structure of kapok fibres. It was confirmed that kapok fibres are a potential alternative to fume silica for super novel VIPs that are green, renewable, and eco-friendly with sustainable performance. [ABSTRACT FROM AUTHOR]