Rigid bio-based wood/polyurethane foam composites expanded under confinement

Rigid polyurethane biofoams (RPUF) were produced by single shot-method using a bio-based polyol and 10 wt% of pinewood particles. Two different confinement degrees were investigated (70% and 50% of the free-rising volume), along with a control group produced under free-rising. RPUF were studied using SEM images (to estimate average foam cell size and anisotropy index), mechanical testing (under compression and tension), apparent density, and thermal conductivity analysis. The results were statistically evaluated using ANOVA tests prior to means tests. The RPUF produced under confinement showed more rounded and homogeneous cell structures compared to those freely expanded. The filled RPUF produced under a confinement degree of 50% yielded very high compressive and tensile strengths, whereas thermal conductivity decreased with confinement.