EFFECT OF CRYSTALLINITY ON THE CELL MORPHOLOGY AND MECHANICAL PROPERTIES OF HDPE/CLAY NANOCOMPOSITE FOAMS

摘要

The effect of crystallinity on the foam morphology and mechanical properties of high density polyethylene/clay nanocomposite foams was studied. Also, the effect of strain rate on the tensile behavior of the foams was investigated. The nanocomposites with various crystallinities were prepared and the microcellular foams were manufactured by a batch foaming process. The samples were characterized by transmission electron microscopy (TEM) and differential scanning calorimeter (DSC), and foam morphologies were studied by scanning electron microscopy (SEM). Nanoclay loadings contributed more to the foaming at a lower crystallinity state. Cell size was decreased as clay content or crystallinity increased. However, as clay content increased, the influence of crystallinity on the variation of cell size was diminished. The Young's modulus and the tensile strength of HDPE/clay nanocomposite foams were reinforced on the whole with crystallinity, while the percent elongations at yield and break were decreased. Also, the Young's modulus increased gradually with increasing the strain rate, but the influence of strain rate was diminished as crystallinity increases.