Terpolymer Blends Research Articles

Multiple morphology in polypropylene/ethylene-propylene-diene terpolymer blends

The morphology of polypropylene/ethylene-propylene-diene terpolymer (PP/EPDM) blends was investigated in the entire composition range by differential scanning calorimetry (d.s.c.), small angle and wide angle X-ray scattering (SAXS, WAXS) and transmission and scanning electron microscopy (TEM, SEM). Only slight changes were observed in the crystalline morphology of PP blends quickly cooled from the melt. On melting and recrystallization at a lower rate, elastomers show β nucleation effect on PP. Above 80 vol% elastomer content crystallization of PP is hindered. Dispersed morphology of the blends shows structural changes as a function of composition: PP is the continuous phase at low and elastomer at high EPDM content; in between a transitional morphology is observed. At high EPDM content, PP is finely dispersed in the statistical copolymer, while it forms large islands in block EPDM.

Miscibility of blends of polymers based on styrene, acrylonitrile and methyl methacrylate

Miscibility of binary blends of homopolymers, copolymers and terpolymers based on styrene (S), methyl methacrylate (M) and acrylonitrile (AN) units was examined by optical clarity and lower critical solution temperature (LCST) behaviour. The blends were systematically classified into six groups according to the number of the monomers included. In each system, miscibility areas were calculated as a function of the monomer composition in the polymers using a binary interaction model and interaction parameters deduced from information available in the literature. Polymer pairs which were predicted to have some zone of miscibility are as follows: PMMA-SAN, PMMA-SMAN, SAN-MAN, SAN-SM, SAN-SMAN, MAN-SMAN, SMAN-SMAN. Experimental observations correspond well to the calculated miscibility zones. All miscible pairs show LCST behaviour. Cloud point curves for SAN-MAN blends and SAN-SMAN blends were determined as a function of AN wt% in the SAN copolymer.

Characteristics of polynorbornene and ethylene‐propylene terpolymer blends

AbstractIn this study characteristics of polynorbornene (PNR) and ethylene‐propylene terpolymer (EPDM) blends were examined in terms of compatibility, cocuring, and ozone resistance. For most of the blend compositions, two glass transition temperatures (Tg) at about −30 and −50°C were observed from differential scanning calorimetry data for both uncured and cured samples. The transitions correspond to the Tg's of the component polymers, suggesting that the blends are microheterogeneous. The two‐phase blends are difficult to cocure as evidenced by the fact that tensile strengths of the blends, when plotted as a function of blend composition, deviate from the linear or additive behavior. Improved cocuring of the blends, however, can be achieved by matching the cure rates of the components. The ozone resistance of the blends containing 25 percent or more EPDM was substantially improved as compared with that of PNR. Therefore, the newly developed PNR can be used for applications requiring ozone resistance by properly blending it with EPDM.

Polypropylene/ABS terpolymer blends. Mixing and mechanical properties

A typical commercial polypropylene and acrylonitrile–butadiene–styrene terpolymer were coextruded and injection molded in various ratios and as the pure components. The rheological properties of the pure components in a single screw extruder were analyzed. Tensile and impact properties were compared with those of the pure polymers. Stress relaxation was analyzed by a simple three-element model. The data were related to the processing conditions. The morphology of the blends was inferred from extractive and staining tests on the blends.