The correlation between packing efficiency and tensile properties for polymer composites in SMC formulation

For polymer composites that find application as sheet‐molding compounds (SMCs), the fiber aspect ratio l/d and the size ratio R (the ratio of the diameter of the spherical filler and the diameter of the fiber) are important parameters. A study of various composite formulations of different combinations of l/d and R has been made to examine the correlation between the packing efficiency of these fibers and fillers in air, and the properties of resulting composites. Samples containing a total of 32 wt% fibers and spherical fillers (in 1:3 proportion) were tested. The tensile modulus was seen to represent behavior similar to packing efficiency. Sources of experimental errors are discussed.