Photo-fabricated unsaturated polyester resin composites reinforced by kenaf fibers, synthesis and characterization

New bio‐fiber composites (UPRC) cured by ultraviolet radiation were produced using kenaf fiber as reinforcing agent and unsaturated polyester resins as matrix in the presence of styrene and IRGACURE 1800 as photoinitiator. Unsaturated polyester resins based on palm oil were prepared from various ratios of monoglyceride (MG)/maleic anhydride (MA) by the interaction of the corresponding MG monomer, with different equivalents of MA, in the presence of 2‐methylimidazole as catalyst. The various characteristics of the obtained bio‐fiber composites, including mechanical, gel content, water absorption and thickness swelling test, thermal analysis, were determined and the data were discussed. Bio‐fiber composite with MG: MA ratio (1 : 4 eq./eq.) showed better mechanical properties (tensile, flexural, and impact strength) than other formulations. Gel content increased as the amount of MA was increased up to the MG: MA ratio was 1 : 4 (eq./eq.) then slightly decreased at the higher ratio formulation. Bio‐fiber composite (UPRCc) was considered the best prepared bio‐fiber composite which contained higher degree double bond, cross‐linking and thermal stability. Moreover, morphological study of selected examples of the formed bio‐fiber composites was also carried out and showed the evidence of the enhancement of the compatibility between fiber and polymer matrix. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011