Cowie-Ferguson model

BPAPC Bisphenol-A polycarbonate CCS-PS Core cross-linked star PS CPSF Carboxylated polysulfone C-F Cowie-Ferguson model Dil Dilatometry... 

Figure 14.6. Comparison of the experimental enthalpy change on aging for t minutes, PMMA, SAN containing 26.6 wt% AN, and a 50/50 blend of these two polymers, with the theoretical curves derived from the Petrie-Marshall (PM) and Cowie-Ferguson (CF) models.

If one is interested in predicting long-term aging effects, one must resort either to the Petrie-Marshall (P-M) [Marshall and Petrie, 1975] or Cowie-Ferguson (C-F) [1986, 1989] models. In both, the enthalpy lost on aging is given by... 

A more comprehensive study of this system has been carried out by Cowie and Ferguson [1991]. These authors followed the enthalpy and stress relaxation of a series of PMMA/SAN blends with SAN compositions spanning the miscibility window, i.e., from 13.3 to 30 wt% AN. It was found that the blends relaxed faster than either of the components, when aging temperatures were (Tg - T ) = 10°C, but that this was no longer the case at (Tg - T ) = 20°C where blend aging was intermediate to both components. The data were analyzed using both the P-M and C-F approaches and examples of AH(t, T ) vs. log t plots are shown in Figure 14.6. The C-F model... 

The first comprehensive study of physical aging in a miscible blend system using enthalpy relaxation was reported by Cowie and Ferguson (1989) who followed the enthalpic relaxatirm in a series of blends of PS and poly(vinyl methyl ether), PVME. ComparisOTi of the blend behavior with that of the two components by analyzing the data oti the basis of both the P-M and C-F models led to the conclusions that the blends aged more slowly than PVME when aging was carried... 

Table 13.3 Physical aging parameters derived from Petrie model for PS/PVME blends (Cowie and Ferguson 1989) ...

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