Dispersive mixing HDPE dispersed phase

EMAA ionomer (0-30 parts) dispersed phase particle size vs. interfacial modifier concentration / emulsification curves / effects of mixing protocol / also blends containing PP in place of HDPE Favis, 1988... 

SEM photomicrographs of blend 1 having HDPE as a matrix in which are dispersed the two minor phases (low-Mw polystyrene/low-Mw PMMA) at 2 min (A) and 15 min (B) of mixing time. PS is extracted by cyclohexane. A stable composite droplet morphology is obtained within 2 min of mixing. The white scale bar denotes 1 pm. (From J. Reignier, B. D. Favis, and M.-Cl. Heuzey, Polymer 44,49-59,2003. With permission.)... 

Blends with high LDPE content show two or three peaks, corresponding to different crystalline phases. These blends have an adverse viscosity ratio and due to this they are not mix well - coarse HDPE drops are dispersed in the LDPE matrix. Co-crystallization may be take place only at the interface between the phases. This may the source of an additional peak in the DSC diagram. Another possible source of the third peak may be a bimodality of crystalline perfection at the interface. Thus, insufficient dispersion of the HDPE droplets, a stepwise concentration profile at the interface, and existence of the LDPE matrix are the reasons for the multiple DSC crystallization peaks in this concentration range of LDPE/HDPE blends. 

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