Lightweight Natural Fiber Insulation Boards Produced with Kapok Fiber (<i>Ceiba Pentandra</i>) and Polylactic Acid or Bicomponent Fiber as a Binder

Traditionally, kapok fiber is employed as filling for soft pillows, bedding, and diverse elements. Due to its buoyancy and proportion between cell wall and lumen, it is also applied as buoyant material in life vests and insulation materials. This study examine slightweight insulation panels produced from kapok fibers. Lightweight insulation boards are produced by hot-air using kapok fibers (95%) bonded with polylactic acid or bicomponent fiber (5%), achieving very low densities of 10,15, and 20 kg.m^-3. The technological attributes like density, porosity, water absorption, wettability, compression, and thermal conductivity, are evaluated against commercial glass wool. In terms of water absorption rates, there is a direct correlation with density. All the variables reach short-term water absorption values less than 1 kg.m^-2, which are comparable to commercial standards. This can be attributed to the lower density, higher porosity of the samples, and the inherent hydrophobic wax layer in the cell wall surface of kapok fibers. This trend is also evident in wettability tests, where produced boards demonstrated water-repellency when exposed to water. Regarding the mechanical property of compression, neither the binder nor the density significantly impacts compression strength. The thermal conductivity performance of kapok-based boards is comparable with commercially available ones.