Biobased polyurethanes and their composites: Present status and future perspective

Abstract

A review of the preparation of polyurethanes using natural resources is provided. Basically, such polyurethanes are produced by combination of petroleum-basedisocyanate reactants with polyols derived from resources such as plant oils, carbohydrates, wood, lignin, cashew, and cork. Depending on the procedure used to derive them from natural resources, polyols with tunable hydroxyl content can be produced. Properties of biobased polyurethanes range from flexible to rigid materials and are thus able to compete with commercially available polyurethanes made from petroleum-based products. Despite a dearth of research on biobased polyurethane composites, this class of reinforced materials is certainly of interest, since addition of fibers such as glass or natural lignocellulosic (i.e., hemp, jute, flax) may result in improved thermomechanical properties, as shown by data collected in our laboratory. When using natural lignocellulosic fibers, formation of covalent bonds between the fiber and the isocyanate component is possible, with improved interaction between the matrix and the fiber.