Anisotropic Measurement of Short Glass Fiber-Epoxy Composites Obtained by Rotational Molding Apparatus

It has been almost impossible to make experimentally composite materials with randomly oriented fillers of a heavy density in matrix resins of low viscosity, because the fillers precipitate out at the bottom of the mold due to gravitation before the liquid resins have time to cure with chemical reactions. In this paper, a new bi-axial rotational molding apparatus to cure the resins containing heavy fillers has been developed and the distribution of short glass fibers and their nickel-coated fibers has been investigated (using this instrument). An aminimide compound, adopted as a latent hardener for epoxy resins, was thermolyzed to generate a tertiary amine for catalysts and an isocyanate at 130°C and above. The results obtained from SEM cross-section photographs and from fiber orientation measurements with a rotative polarization system of millimeter waves showed a random orientation of fibers. The moduli of the composites measured by flexural tests were very close to the values calculated from Nielsen's theoretical equation for random orientation in orthogonal directions.