Wood fiber insulation (WFI) boards are produced by bonding together wood fibers with polyurethane/polyurea-based binders. The presence of air gaps in-between the fibers results in materials with relatively low thermal conductivities with λ10 values of typically 35-50 mW/(m-K). In this work, we attempt to further improve WFI's thermal insulation performance by using emulsifiable MDI (methylene diphenyl diisocyanate) as a binder. The findings will examine the synthesis and characterization of WFI products where air gaps have been partially filled with silica aerogel particles. Thermal conductivities as low as 18 mW/(m-K) were achieved, which represents a step-change not only compared to conventional WFI, but also compared to conventional closed-cell insulation foams, which typically have λ10 values above 20 mW/(m-K). Significant improvements in both mechanical and fire properties were also achieved.
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