Binderless Thermal Insulation Boards from Rapeseed Straw: Optimization and Performance Analysis

The development of sustainable thermal insulation materials is crucial for reducing the environmental impact of the construction sector. This study investigates the potential of binderless insulation boards made from rapeseed fibers, utilizing the natural adhesive properties of lignin. The effects of fiber fineness and processing temperature (160 °C and 180 °C) on basic physical, hygric and thermal properties were examined. The influence of temperature on thermal conductivity was minimal, while higher temperature slightly reduced moisture content and swelling. Finer fibers and higher temperature increased the water vapor diffusion resistance factor. Microscopy and thermal analyses confirmed sufficient lignin softening and fiber bonding at 160 °C, whereas higher temperatures caused partial fiber degradation. Overall, the results demonstrate that rapeseed straw boards provide a sustainable and vapor-permeable alternative for roof and general insulation applications, with processing conditions and fiber fineness influencing hygric properties more than thermal performance.