Hybrid polyurethane/natural fibers composites optimized by simplex-centroid mixture design

Abstract

Low-cost hybrid polyurethane/natural fibers composites were developed and characterized in terms of elastic modulus, resilience, permanent deformation in compression test, and ash content. Composites manufactured in the form of foams were made with partial replacement of 10% (w/w) of polyethylene glycol by natural fibers from rice husk (R.H.), cassava bagasse (C.B.) and wood fiber (W.F.). Composites containing untreated fibers and mercerized fibers were also developed. A simplex-centroid mixture model was used for statistical analysis of the effects caused by the addition of the fibers. Based on the complete cubic model considering all the interactions, it was possible to obtain the common optimum, regarding all the properties studied. For hybrid composites with natural fibers, the optimal composition is 4.5% of C.B. and 95.49% of W.F. while for composites with mercerized fibers is 39.24% of R.H., 26.30% of C.B., and 34.46% of W.F.