Structural development of poly(ethylene terephthalate) during uniaxial stretching above the glass-transition temperature: Study of the statistical influence of the stretching variables

• Published in: Journal of applied polymer science Vol. 120; no. 3; pp. 1253 - 1265
• Main Authors: Todorov, Lyudmil V, Martins, Carla I, Viana, Júlio C
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 05-05-2011; Wiley; Wiley Subscription Services, Inc
• Subjects: Applied sciences; Birefringence; Crystallinity; Design of experiments; Differential scanning calorimetry; differential scanning calorimetry (DSC); Exact sciences and technology; Glass transition temperature; Materials science; Organic polymers; Orientation; orientation polyesters; Physicochemistry of polymers; Polyethylene terephthalates; Polymers; Properties and characterization; Stretching; Structure, morphology and analysis; Terephthalate; WAXS; Ethylene terephthalate polymer; differential scanning calorimetry (DSC); Ester polymer; Temperature effect; Crystallinity; Experimental study; Glass transition temperature; WAXS; Uniaxial drawing; Thermal properties; Structure processing relationship; Hot drawing; Molecular orientation; Experimental design; drawing; X ray scattering; orientation polyesters
• ISSN: 0021-8995; 1097-4628; 1097-4628
• DOI: 10.1002/app.33099

In this article, we present an investigation of the structural development of poly(ethylene terephthalate) (PET) during uniaxial stretching above the glass-transition temperature; this followed a statistical design of experiment approach to determine the influence of the stretching variables on the structural development. Amorphous PET was submitted to a stretching program with variations in the stretching temperature (Tst), stretching rate ( $\dot {\varepsilon}_{st}$), and stretching ratio (λst). Stretched samples were rapidly quenched and characterized by wide-angle X-ray scattering, optical birefringence, and differential scanning calorimetry. The relevance and influence of the stretching variables on the obtained parameters (phase fraction, phase orientation, and thermal parameters) were analyzed. The strain-induced crystallinity was controlled by Tst, λst, and the interactions between them. Mesophase development was not dependant on Tst but on the interactions between $\dot {\varepsilon}_{st}$ and λst. The molecular orientation was proportionally dependent on Tst, λst, and their interactions.