Thermal Stability and Crystallization Behavior of TER Blends of Isotactic Polypropylene (iPP)/Ethylene-Propylene Diene Rubber (EPDM)/Nitrile Rubber (NBR)

Abstract

The blends of isotatic polypropylene (iPP), ethylene-propylene diene rubber (EPDM), and nitrite rubber (NBR) were prepared using dimethylol phenolic resin as a crosslinking system. The dynamically crosslinked blends of iPP/EPDM/NBR showed superior thermal stability to that of virgin isotactic polypropylene (iPP). Dynamic crosslinking rendered the vulcanizate thermally more stable as compared to uncrosslinked blends, which can be attributed due to the variations in degree of crosslinking and degree of crystallinity.

Crystallization of iPP in the blends of iPP/EPDM/NBR was also studied through Temperature Modulated Differential Scanning Calorimetry (TMDSC). Other detailed analysis of endotherm peaks obtained after first and second melts in terms of heat of enthalpy, degree of undercooling, and degree of crystallinity were also evaluated. Various kinetic parameters were also determined. Degree of crosslinking increases the interfacial adhesion between the iPP and EPDM/NBR phases. Dimethylol phenolic resin used as a compatibilizer also enhanced the thermal stability of the iPP/EPDM/NBR blends.

Keywords:

• crosslinked
• crosslinking effect
• crystallization
• degree of crystallinity
• kinetic parameter
• temperature modulated differential scanning calorimetry (TMDSC)
• thermal degradation
• uncrosslinked

Notes

*Degree of crystallinity of the virgin iPP was calculated by Differential Scanning Calorimetry (DSC) method.

*Weight % based on EPDM/NBR elastomer.

**Weight % based on isotactic polypropylene.