The aim of the study was to improve the electrical and thermal conductivity of the polylactic acid/wood flour/thermoplastic polyurethane composites by Fused Deposition Modeling (FDM). The results showed that, when the addition amount of nano-graphite reached 25 pbw, the volume resistivity of the composites decreased to 10⁸ Ω·m, which was a significant reduction, indicating that the conductive network was already formed. It also had good thermal conductivity, mechanical properties, and thermal stability. The adding of the redox graphene (rGO) combined with graphite into the composites, compared to the tannic acid-functionalized graphite or the multi-walled carbon nanotubes, can be an effective method to improve the performance of the biocomposites, because the resistivity reduced by one order magnitude and the thermal conductivity increased by 25.71%. Models printed by FDM illustrated that the composite filaments have a certain flexibility and can be printed onto paper or flexible baseplates.

The growing demand for lightweight, renewable, and excellent thermal insulation materials has fueled a search for high performance biomass materials with good mechanical compressibility and ultralow thermal conductivity. We propose a fabrication method for making a lightweight, anisotropic, and compressible wood aerogel with aligned cellulose fibers by a simple chemical treatment. The wood aerogel was mainly composed of highly aligned cellulose fibers with a relative crystallinity of 77.1%. The aerogel exhibits a low density of 32.18 mg/cm³ and a high specific surface area of 31.68 m²/g due to the removal of lignin and hemicellulose from the wood. Moreover, the multilayer structure of the aerogel was formed under the restriction of wood rays. Combined with a nanoscale pore, the aerogel presents good compressibility and an ultralow thermal conductivity of 0.033 W/mK. These results show that the wood aerogel is a high quality biomass material with a potential function of thermal insulation through optimizing structures.