Effect of fiber surface treatment on the structure and properties of rigid bagasse fibers/polyurethane composite foams

Abstract Bagasse fibers reinforced rigid polyurethane foams were successfully prepared by one‐step method. In order to improve the interfacial bonding strength between the filler and matrix, the bagasse fiber was modified by alkali treatment before incorporation into the foams. The surface roughness of the fiber increased after treatment and chemical bonding formed between the ‐OH groups on the fibers and the excess ‐NCO groups, which improved the interfacial interactions between the filler and matrix. With the increase of fiber content, the close cell ratio decreased, however, the thermal conductivity of rigid polyurethane foams almost unchanged. The mechanical performance decreased with the increase of fiber content, but the specific strength and modulus exhibited different changing trends for the reinforcing effect of the fibers on the matrix. The dimensional stability of the foams was greatly enhanced with incorporation of bagasse fibers. When the bagasse fiber content reached 40 wt%, the dimensional stability was best, and the dimensional change rates in the three directions of length, width, and height were less than 1%. These composite foams with improved performance were in line with the current trend of green environmental protection and would possess wide applications in sound/heat insulation, industrial manufacturing, packaging industry, and hence forth.