| Abstract: | The effect of diethylene glycol (DEG) on the crystallization of poly(ethylene terephthalate) (PET) was studied under isothermal and dynamic conditions. The strain-induced crystallization of PET and its relationship to DEG content was also studied. The samples were isothermally and dynamically crystallized in the differential scanning calorimeter (DSC). The thermograms were then analyzed to determine the kinetic parameters. Strain-induced crystallization was studied by stretching samples at different strain rates. These samples were then annealed for various periods of time and quenched to room temperature. Birefringence and density were measured on the annealed samples. Results indicate that the DEG content reduces the rate of crystallization of PET when crystallizing from the melt, isothermally and dynamically. When crystallizing from the glassy state, the effects of DEG are not prominent. The mechanism of crystallization is not affected by the amount of DEG, within the range of DEG contents evaluated. In the case of strain-induced crystallization, increased DEG content reduces the crystallinity of PET at intermediate strain rates, but at higher strain rates, the crystallinity is not affected by the DEG content. © 1993 John Wiley & Sons, Inc. |
