The authors had already reported that the mechanical properties of composites filled with micro-balloon fillers relate to the surface condition of fillers. In this study, the relationship has been surveyed between the mechanical properties of composites and the surface condition of fillers by the use of the oyster shell particles as the filler. The positive effect has been demonstrated on the mechanical properties of composites from the measurement of Young's modulus and the breaking strength of composites. In addition, the numerical modelling of Young's modulus of the composites filled with oyster shell particles has been made to confirm the experimental results. The results of the model calculation has shown the remarkable effect on the mechanical properties of composite due to the delayed separation between the filler and the matrix caused by the roughness of the filler surface.

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The authors examined the evaluation of the effect of sizing on the physical property (bending rigidity) of fabrics by using a dynamic modulus tester.
The sound velocity and the bending rigidity, B of KES system, increased with the concentration of PVA, and decreased with the random tumbling action. The sound velocity and bending rigidity were expressed in values relative to those of untreated fabrics respectively. It was found that the relative sound velocity corresponded with the relative bending rigidity irrespective of a specimen and its direction.
On the relative bending rigidity vs. sound velocity graph, the regression line (for both variables>1) is useful for predicting the bending rigidity of sized fabrics. In the area where both variables are below 1 on the relative bending rigidity vs. sound velocity graph, it is presumed that the decrease of the sound velocity is due to wrinkles caused by random tumbling. Therefore, there would be a possibility that the dynamic modules tester can be used as a wrinkle tester.

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