Investigation of the miscibility of polycarbonate–poly(ethyleneterephthalate) blends: Solid‐state ¹H‐NMR T₁ relaxation time measurements, transmission electron microscopy, and structure–properties relationship

Abstract

Solid‐State 1H‐NMR measurements of T1 relaxation times performed on polycarbonate‐poly(ethyleneterephthalate) (PC–PET) blends point out the presence of two separate domains with apparent dimensions of about 80 nm. The variation of PET domain relaxation time with the increase of PC content is explained in terms of an interface in which parts of the PC molecules are finely dispersed into the PET matrix. Relaxation parameters and compositions match very well an equation that quantitatively describes a three‐phase model formed by two domains separated by an interface of mixed components. Micrographs obtained by transmission electron microscopy (TEM) clearly reveal the presence of two separate domains with a phase inversion at 40/60 wt% composition. PET domains, although larger than expected from NMR analysis, are characterized by a dispersion of small PC particles that are considered responsible for the observed diffusion of magnetization from PET to PC domains. The partial miscibility seems to be physical in nature rather than due to transesterification processes between the components, as stem from 1H‐NMR spectra in solution of PET and PC–PET blends. T1 relaxation times measured in the same way on totally immiscible PC–PA‐6 blends, support, by contrast, the NMR interpretation of PC–PET results. The mechanical properties of PC–PET blends exhibit ductile behavior throughout the entire range of composition. This indicates that PC and PET are mechanically compatible. This is also in agreement with the isothermal crystallization data for PET at various compositions of PC–PET. These results are in agreement with the existence of a partial miscibility between PET and PC. © 1994 John Wiley & Sons, Inc.

Effects of composition and transesterification catalysts on the physico-chemical and dynamic properties of PC/PET blends rich in PC

“…PC90 blend has the finest dispersed phase compared with PC80 or PC70 that have a less uniform dispersion with a higher number average particle size. Significantly, the number average particle size of dispersed phases that are mentioned here are in the same range that has been cited by other works for blends containing equal or more than 10% by weight of PET [27][28][29][30].…”

Tuning the optical clarity of glass fiber‐reinforced polycarbonates by reactive blending with alternatives from biorenewable isosorbide

“…Melt transesterification‐induced intermolecular chain exchange reactions are well known between BPA‐PC and poly(ethylene terephthalate) or poly(butylene terephthalate) . Both the end‐group‐activated exchanges, that is, the active chain ends, attack the functional groups located inside the polymer chains (named as outer–inner exchange), and the direct exchange between the inner functional groups (inner–inner exchange) may occur in the presence of a suitable catalyst.…”