A series of epoxy resin (EP) composites were prepared using ground pearl shell powders, which had been calcined at various temperatures. The EP composite containing similar to 3% weight content of the calcined pearl shell powder had the highest impact strength and the presence of silane agent was found to be essential for the composite formulation. The impact strengths of the resultant EP composites were highly influenced by the specific surface area, surface morphological structure, and chemical composition of the calcined pearl shell powder, The highest mechanical improvement was obtained for the EP composite prepared with the pearl shell powder calcined at 700 degrees C for 3 h. The layered biopolymeric materials were completely degraded for the pearl shell powder calcined at 700 degrees C, resulting in "sponge-like" or "net-like" porous calcium carbonate powder. However, the degradation of the layered biopolymeric materials was not complete for the calcinations at lower temperatures (< 600 degrees C), while calcium carbonate decomposed to form calcium oxide at higher temperatures (> 800 degrees C). The mechanical improvements of the processed EP composites have been discussed along with the chemical compositions and surface microstructures of the incorporated pearl shell powders. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114:3168-3176,2009