February 2000
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Polymer Testing
Polyacetal/thermoplastic polyurethane blends at four different polyacetal wt% of 90, 80, 70 and 60 were made using a twin screw extruder. Mechanical, morphological and rheological properties of these blends were determined. The addition of thermoplastic polyurethane (TPU) to polyacetal produces a decrease of tensile and flexural strength of the blend material as the TPU wt% increases. The notched impact strength increases with the increase of TPU wt% in the blends. Scanning electron micrographs of impact fractured surfaces of these blends show droplet dispersion morphology. The melt flow curves for these blends show lower melt viscosity than those of feedstocks in the major range of experimental shear rates. The instrumented impact strength of these blends at 30wt% TPU level are nearly nine times higher than that of polyacetal, and blends at 30 and 40wt% TPU levels failed in a ductile manner, whereas the polyacetal failed in a brittle manner.