Abstract: The rheological properties of plasticized polyvinyl alcohol (PVA) were investigated with capillary rheometer. The effect of cooling rate on crystallization propertities of PVA was studied with differential scanning calorimetry analyzer (DSC). The PVA foams were fabricated by filling chemical foaming agent through melt extrusion, and the cell morphology and the density of the foams were investigated with scanning electron microscope (SEM) and density tester. PVA was sensitive to the shearing effect. At low shear rate, the melt viscosity of PVA was high, leading to the homogeneous distribution of the cells and a low density; at high shear rate, the melt viscosity of PVA was low and the gas was easy to escape, leading to the break or combination of the cells. At low cooling rate, the melt viscosity was low, leading to the combination or collapse of the cells; at appropriate cooling rate, the distribution of cell diameter was homogeneous; with further increase of cooling rate, the cell combined due to the excessive gas pressure, resulting in the high density of the foams.

Key words: poly（vinyl alcohol）, rheological behavior, crystallization, cell morphology, apparent density