초록 |
The effect of reaction rate on the morphology of reactive blends has been studied using 75/25 (wt/wt) mono-carboxylated polystyrene [PS-mCOOH]/poly(methyl methacrylate) [PMMA] with poly (methyl methacrylate-ran-glycidyl methacrylate) [PMMA-GMA] as an in-situ compatibilizer, by varying the amount of PMMA-GMA in the blend, the molar concentration of GMA, CGMA, 0 in PMMA-GMA at fixed molecular weight, and the molecular weight of PMMA-GMA at fixed CGMA, 0. For the blends with PMMA-GMA having lower CGMA, 0, there exists a critical amount of PMMA-GMA above which a sharp decrease in the volume average domain size (Dv) occurs. This amount was shifted to a smaller value with increasing CGMA, 0 in PMMA-GMA. We demonstrated that the interfacial graft reaction between PS-mCOOH and PMMA-GMA at 220 oC was described by the simple second-order reaction kinetics, i.e., mean field reaction kinetics. From the morphological evolution, it is found that the morphological change by an external flow from a pellet size to Dv withless than 1 ?m occurred within a very short time of ~ 30s. After this transition, coalescence is the main mechanism for determining the final morphology obtained at a mixing time of 20 min. Finally, a master curve is obtained when Dv is plotted against CGMA, 0, implying again that the concept of mean field reaction kinetics adequately applies to the blends employed in this study.
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