Interphase transfer of plasticizer between immiscible rubbers

- The interphase transfer of a plasticizer occurs between immiscible rubbers.
- The driving force of the transfer is the difference in the interaction parameter.
- The temperature dependence of interaction parameter is evaluated.
- The plasticizer transfer affects the glass transition temperature of each rubber.
- The transfer phenomenon can be applicable for an all-season tire.

Interphase transfer of di-2-ethylhexyl adipate (DOA) between ethylene-propylene copolymer (EPR) and polyisobutylene (PIB) in the laminated sheets was studied. It was found that the amount of DOA in each phase is determined by the ambient temperature. DOA moved to EPR from PIB at −20 °C and vice versa at 40 °C, when the DOA content before lamination was 10 phr. This is attributed to the change of interaction parameters between DOA and each rubber as a function of temperature. Because of the DOA transfer, the glass transition temperature of each rubber phase changes with the ambient temperature. The phenomenon can be applicable to an all-season tire, when a matrix polymer contains more plasticizer at low temperature and vice versa in a blend with sea-island structure.

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