Properties of copolymer-type polyacetal/ethylene–propylene–diene terpolymer blends

Two kinds of polymer blends, polyacetals (POMs) and ethylene–propylene–diene terpolymer (EPDM), have been prepared by mechanical blending. The rubbery EPDM was added to the rigid POM matrix to increase toughness. The mechanical, physical, thermal, dynamic mechanical, and morphological properties of these samples have been measured. The notched Izod impact strength and the elongation of the blends reaches a maximum at 7.5 wt % EPDM content. Scanning electron micrographs (SEM) showed that the domain sizes of EPDM vary from 0.25 to 1.0 μm and were independent of the composition. The POM/EPDM blends were determined to be immiscible by SEM, but showed single T_g behavior as determined by differential scanning calorimetry (DSC) and dynamic mechanical analyses up to 7.5 wt % EPDM. Because of that, the T_g's of POM and EPDM were very similar in value. © 1993 John Wiley & Sons, Inc.