The analysis and correlation of the RPUF porous structure parameters with the material properties measured at various directions was a crucial part of the conducted research as the properties of the RPUF are highly dependent on the pore structure. The cross sections of obtained materials were analysed using scanning electron microscopy(SEM) in order to determine the differences in pore size and shape statistics. The example SEM images are presented in Fig. 9. The most uniform pore size distribution was observed in the case of samples containing 25% and 50% of the plant-based polyol in the polyol premix. The analysis of the SEM images of the samples suggested the significantly lower pore size distribution of the 100PP, 75PP/25RP and 50PP/50RP materials compared to the 25PP/75RP and 100RP materials,which is reflected in the standard deviation of the pore size distribution (Table8).The materials containing 75% and 100% of the plant-based polyol exhibited lower apparent density, leading to the bigger pore size and anisotropy,