A small-angle X-ray scattering study of the effect of chain architecture on the shear-induced crystallization of branched and linear poly(ethylene terephthalate)

Hanley, T.; Sutton, D.; Heeley, E.; Moad, G. and Knott, R. (2007). A small-angle X-ray scattering study of the effect of chain architecture on the shear-induced crystallization of branched and linear poly(ethylene terephthalate). Journal of Applied Crystallography, 40(Supp.) pp. 599–604.

DOI: https://doi.org/10.1107/S0021889807003512

Abstract

The synchrotron-based small-angle X-ray scattering (SAXS) technique was used to investigate the shear-induced crystallization kinetics of branched/unbranched poly(ethylene terephthalate) (PET). Reactive extrusion of bottle-grade PET with the branching and chain-extension agents pyromellitic dianhydride and pentaerythritol results in enhanced rheological properties, such as higher melt strength and higher viscosity. In this study, six samples of PET were investigated: linear PET [intrinsic viscosity (IV) ≈0.76 dm³ g^-1]; four branched PETs produced from linear PET by a reactive extrusion technique (IV ≈0.86-1.06 dm³ g^-1); and a control PET (IV ≈0.73 dm³ g^-1) extruded under the same conditions without reactive agents. SAXS data were recorded for the PET at the melt temperature and time-resolved SAXS data were recorded following the application of a step shear (53 s^-1 for 2 s). As the PET IV was increased, the extent of shear-induced orientation increased, whilst the time taken for the polymer to initiate and complete crystallization decreased.

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