New composite materials based on biosourced polyurethane: Elaboration and study of their thermal and mechanical properties

Polyurethane (pu) based on castor oil,4.4'diphenyl methylene diisocyanate and 1,3-propane diol was synthesized in two-steps. the composites were obtained by blending the pu with various amounts of cellulosic fibers extracted from the moroccan alfa stems (esparto grass plant). the influence of the cellulosic fiber ratio on the thermal and mechanical properties of the composites was demonstrated by means of several characterization techniques,such as thermal,mechanical,structural,and morphological analyses. the hydrogen bonding interaction and the possible formation of urethane bonds between pu and the hydroxyl groups of the cellulose provides a good fiber-matrix interface. the variation of glass transition temperature,tg,versus cellulose content is linear. however,the mechanical properties increased up to 20 wt % of fibers and decreased beyond this value.