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Evaluation of Microstructure and Free Volume in Polyesters caused By Orientation and Antiplasticizers

Zekriardehani, Shahab

Abstract Details

2017, Doctor of Philosophy, University of Toledo, Chemical Engineering.
Polyethylene terephthalate is a semicrystalline polymer that has been widely used in the packaging industry due to its excellent processability, good mechanical properties, excellent transparency, and acceptable barrier properties. However, packaging industry needs increased shelf life and improved permeability of carbon dioxide and oxygen to make PET suitable for keeping a wider range of products for a longer time. Over the past decades, a number of methods have been employed and yet a great deal of research is being conducted in both academia and industry to further enhance the barrier properties of PET. Recent research works show that using antiplasticizers is an effective way to enhance the barrier properties of PET by lowering the free volume and consequently reducing the permeability. Dimethyl terephthalate (DMT) and dimethyl isophthalate (DMI) were chosen as the additives for this work, since they show high compatibility with PET based on their solubility parameters. In addition of incorporation of antiplasticizers, strain induced crystallization is a common method to enhance the barrier properties of PET which is rapid, does not affect the transparency, and results in a two-fold barrier improvement. In this work, a detailed study on the microstructure of PET upon strain induced crystallization was performed. In the first phase of this work, PALS measurement was used as a complementary technique to study the change in average free volume and free volume distribution. Presence of RAF and MAF, free volume of each phase, and solubility of each phase was reported for the first time and finally the effect of these parameters on the permeability of CO2, O2, and He was discussed. In the second phase of this work, two additives were chosen and incorporated into PET via extrusion. Occurrence of any chemical reaction between Pet and the additives was investigated using NMR and the concentration of the additives was quantified by TGA. Change in the microstructure was investigated by means of various techniques to deeply understand the effect of presence of antiplasticizers on the barrier properties of amorphous PET blends. In the last phase, proper processing condition for maintaining similar percent crystallinity to pure PET was investigated and optimized. Further reduction in the permeability of Pet blends was observed upon strain induced crystallization and was attributed to change in chain motion, average free volume, free volume distribution, and presence of crystalline structures within PET matrix.
Saleh Jabarin (Committee Co-Chair)
Maria Coleman (Committee Co-Chair)
Joseph Lawrence (Committee Member)
Matthew Liberatore (Committee Member)
Yong Wah Kim (Committee Member)
207 p.

Recommended Citations

Citations

  • Zekriardehani, S. (2017). Evaluation of Microstructure and Free Volume in Polyesters caused By Orientation and Antiplasticizers [Doctoral dissertation, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1513370162281092

    APA Style (7th edition)

  • Zekriardehani, Shahab. Evaluation of Microstructure and Free Volume in Polyesters caused By Orientation and Antiplasticizers . 2017. University of Toledo, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=toledo1513370162281092.

    MLA Style (8th edition)

  • Zekriardehani, Shahab. "Evaluation of Microstructure and Free Volume in Polyesters caused By Orientation and Antiplasticizers ." Doctoral dissertation, University of Toledo, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1513370162281092

    Chicago Manual of Style (17th edition)