Degree of transesterification

This article is an overview of the novel technology of self-reinforced LCPs with polyesters, poly(ethylene terephthalate) (PET) and poly(ethylene naphtha-late) (PEN) [10-13, 21, 23], LCP/polyester blends in a polyester matrix form in situ fibrils which improve the mechanical properties. LCPs have an inherently low melt viscosity, and provide LCP/polyester blends that effectively lower the melt viscosity during melt spinning [24], and fast injection-molding cycles. The miscibility between the LCP and polyesters can be controlled by the degree of transesterification [25] in the reactive extrusion step, and fibril formation in LCP-reinforced polyester fibers has been studied. 

PET and PEN form immiscible mixtures. Improved miscibility can be obtained by performing a transesterification reaction between both ingredients to produce copolyesters, which act as compatibilizers in the interface of the blend. This reaction, when carried out in a melt extruder, depends strongly on temperature and residence time, in particular, within 50-80 wt% PEN content [63]. Physical and mechanical properties of the resulting blend depend on the degree of transesterification and also on the resulting copolymer... 

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