The cure behavior of SMC (Sheet Molding Compound) during compression molding is rather complicated due to heat generation during the cure process and the heterogeneity of the SMC material. The cure behavior is the most important factor for designing SMC products and the mold itself, because cure behavior affects not only the post-deformation state of products after they are removed from the mold but also the flow patterns in the mold. DSC (Differential Scanning Calorimeter) may be an effective and powerful method for studying the cure behavior of various materials but is not as useful for practical products, because the dimensions of DSC specimens are much smaller than that of practical products. Consequently, this means that SMC shows considerable heterogeneous properties for minute specimens. This paper describes a numerical analysis method for studying the cure behavior of SMC. Combining measured temperatures inside the SMC, three-dimensional heat conduction analysis, and considering the heat generation due to chemical diffusion, the heat generation was determined by both data and consequently was defined as a function of temperature inside the SMC. The obtained heat generation function was again used in the heat conduction analysis. Thus, it was possible to obtain a practical temperature-time curve, curing profile and other properties.

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Melts of thermotropic liquid crystalline polymers filled with glass and carbon fibers were examined for their steady shear flow and dynamic viscoelastic properties using two types of rheometers. In these fiber-filled systems, the shear viscosity increased with increasing fiber content, showing a large increase in the low shear rate region. In addition, the relative viscosity of the fiber-filled systems increased as their fiber content increased, although it showed a decrease with increasing shear stress, the same behavior as observed in the case of ordinary fiber-filled non-liquid crystalline polymers. The first normal stress difference of the fiber-filled systems increased with increasing fiber content, showing a remarkable increase in the case of the carbon fiber-filled system. The dynamic viscoelasticity of the fiber-filled systems measured using a rotational type rheometer was found to be governed by the type of liquid crystalline polymers in the systems and their fiber content, with an increase in fiber content causing a rise in viscosity. In addition, liquid crystalline polymers filled with glass fiber and carbon fiber were examined for the temperature dependency of their flow properties by applying the Williams, Landel & Ferry (WLF) formula representing the temperature dependency of viscosity in order to determine the constants C₁ and C₂ in the formula for the fiber-filled systems. The results of this examination showed that C₁ mainly depends on the type of fiber used as a filler in the system and its shape and C₂ significantly depends on the chemical structure of the liquid crystalline polymer used as a dispersion medium in the system and its molecular weight.

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The morphology and tensile properties of polyacetal in molded standard bars with a weld line were investigated. The morphology of the samples without weld lines showed a layer structure with skin, middle and core layers. The weld line region morphology of the samples with weld lines contained transcrystalline and core regions. The samples without weld lines broke after necking. The yield strength of the samples without weld lines increased with increasing mold temperature and decreasing cylinder temperature. The displacements of the samples without weld lines decrease with increasing mold temperature and decreasing with cylinder temperature. The samples with weld lines broke after cracking at weld lines. The yield strength of the samples with weld lines increased with increasing mold temperature. The displacements of the samples with weld lines were decreased by the cracking at weld lines.

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