Experimental study on thermal and morphological analyses of green composite sandwich made of flax and agglomerated cork

Abstract

The building sector has been showing great interest in incorporating technologically advanced materials with lightweight, ecofriendly, high strength, and stiffness properties in flooring, roofing, and partition walls, etc. In addition to the mechanical properties, these materials should have good thermal properties as well. In response to these requirements, an attempt has been made to study the thermal behavior of green composite sandwich made of flax and agglomerated cork. Composite sandwiches were fabricated by using flax as skin reinforcement and agglomerated cork as core with different densities as 240, 280, and 340 kg m⁻³ using vacuum bagging method. Glass was also used as skin reinforcement for manufacturing composite sandwiches for comparison purpose. Experiments were conducted to predict thermal properties, viz. thermal conductivity, thermal expansion, flammability, and thermal stability. The experimental results show that the lowest thermal conductivity of 0.03 W m⁻¹ K⁻¹ was observed in flax-based composite sandwich having core density of 240 kg m⁻³; the lowest thermal expansion of 29.2 × 10⁻⁵ °C⁻¹ was observed in glass-based composite sandwich having core density of 340 kg m⁻³; the highest value of time to ignition was 12 s, and minimum propagation rate was 0.25 mm s⁻¹ in flax-based composite sandwich having core density of 340 kg m⁻³; The highest initial degradation temperature was 362 °C for glass-based skin and 263 °C for cork having density of 240 kg m⁻³.