Luận án tiến sĩ: Tổng hợp và đặc trưng polymer rào cản oxy hoạt tính - Kamal Mahajan (Đại học Toledo, 2010)

A Dissertation entitled Synthesis and Characterization of New Active Barrier Polymers By Kamal Mahajan Submitted to the Graduate Faculty as partial fulfillment of the requirements for the Doctor of Philosophy Degree in Engineering Dr. Jabarin, Committee Chair Dr. Coleman, Committee member Dr. Escobar, Committee member Dr.

Cameron, Committee member Dr. Yong Wah Kim, Committee member Dr. Patricia Komuniecki, Dean College of Graduate Studies The University of Toledo May 2010 Copyright 2010, Kamal Mahajan This document is copyrighted material. Under copyright law, no parts of this document may be reproduced without the expressed permission of the author.

An abstract of Synthesis and Characterization of New Active Barrier Polymers by Kamal Mahajan Submitted to the Graduate Faculty in partial fulfillment of the requirements for the Doctor of Philosophy Degree in Engineering The University of Toledo May 2010 For many foods and beverages, a fundamental requirement for shelf stability is the minimization of oxygen exposure and thus minimal possible reaction with the food. Common problems associated with the presence of oxygen in food products include microbial spoilage, nutrient loss, as well as flavor and odor changes. There is a need in the industry to improve the oxygen barrier properties of polyesters. Among the approaches available to improve the barrier properties, one of the most promising approaches is the addition of an active oxygen scavenger directly into the poly(ethylene terephthalate) (PET) material.

An active oxygen scavenger is a substance capable of intercepting and scavenging oxygen by undergoing a chemical reaction with it, as the oxygen permeates through the PET packaging wall. There is also a need to develop a methodology for determining the scavenging capacity of potential oxygen scavengers and to ultimately help in efficiently designing the copolymers of PET and potential scavengers with better barrier properties. iii The oxygen scavengers used in this research were two simple model compounds: monoolein (MO) and 3-cyclohexene-1,1-dimethanol (CHEDM). The new active barrier copolymers were synthesized by melt polymerizing PET with the oxygen scavengers in a batch scale polymerization system.

It was found using proton NMR (1H NMR) and 2-D correlation spectroscopy (COSY) that PET has reacted with MO and CHEDM leading to the formation of the copolymers. The effect of oxygen scavengers on the physical properties (melting, crystallization, and rheological behavior) of PET was also studied. The effects of oxygen scavengers on the barrier properties of PET were evaluated by determining oxygen permeation rates. The oxygen barrier properties of copolymers of PET/MO and PET/CHEDM were respectively improved by about 30 and 40%.

The oxidation by-products of the copolymers were determined by using gas chromatography- mass spectrometry (GC-MS). Finally, a methodology was developed to determine the scavenging capacity of potential oxygen scavengers by studying the oxidation kinetics followed by the calculation of Thiele modulus. The oxidation kinetics of the copolymers of PET and oxygen scavengers was determined by using nuclear magnetic resonance spectroscopy (NMR) and fourier transform infrared spectroscopy (FTIR). iv Dedication This dissertation is dedicated to my family and Dr.

Jabarin for their constant support and love. v Acknowledgements First I would like to express thanks to my advisor, Dr. Jabarin, for giving me this great opportunity to work with him on this project at the Polymer Institute. Without his invaluable guidance, encouragement and support throughout my dissertation research, the completion of this work would not have been possible.

Many thanks are due to Ms. Lofgren for her valuable advice, teaching me analysis techniques and reviewing my dissertation. I am very grateful to Mr. Mike Mumford for his assistance in using the lab equipments at the Polymer Institute.

Thanks are due to Dr. Cameron and Dr. Yong Wah Kim for their help and support throughout this work. Thanks also to Ms.

Zydorczyk for her kind help. I especially would like to thank Dr. Escobar, and Dr. Yong Wah Kim for serving on my dissertation committee.

My grateful acknowledgement is also given for the financial support provided by the PET and Active Barrier Industrial Consortium. Finally, I would like to thank all my friends in the University of Toledo for their support and friendship making my stay at the Polymer Institute a memorable one. vi Table of Contents Abstract………………….vi Table of Contents………………….vii List of Figures………………………………….………………xiii List of Tables……………………………….1 Active oxygen scavenger………………………………………………………….2 Polymerization of PET/scavenger copolymers……………………………………4 1.3 Reaction analysis of PET/scavenger copolymers…………………………………6 1.4 Literature review of PET copolymers.1 PET as a passive barrier……………………………………………………….2 PET modified with oxygen scavengers……………………………………….1 PET modified with oxidizable groups in its main chain…………………12 vii 1.2 Advantages of PET modified with oxidizable groups versus sachet and iron based films……………………….3 Disadvantages of PET modified with oxidizable groups……………….3 PET with non-oxidizable pendant groups…………………………………….4 PET with oxidizable pendant groups………………………………………….5 Projected advantages of PET modified with oxidizable pendant groups…….5 Oxygen transmission rate/Permeability………………………………………….6 Rationale and objectives…………………………………………………………19 1.7 Selection of active oxygen scavengers for this research…………………………22 Chapter 2.3 Preparation of the physical blends……………………………………………….6 Melt IV/Intrinsic viscosity measurement……………………………………….8 Solid state polymerization……………………………………………………….10 Single screw extrusion………………………………………………………….11 Barrier property measurement………………………………………………….13 Microscopy of PET/scavenger copolymers…………………………………….2 Small angle light scattering…………………………………………………44 2.14 GC-MS analysis………………………………………………………………….15 Gas chromatographic analysis………………………………………………….16 Oxygen scavenging capacity calculations………………………………………. Results and Discussion 47 3.1 In situ polymerization of PET/scavenger copolymers………………………….2 Reaction analysis between PET and MO using NMR spectroscopy…………….1 1H NMR spectrum of pure PET………………………………………………49 3.2 1H NMR spectrum of pure MO……………………………………………….3 1H NMR spectra of PET/MO copolymer…………………………………….4 COSY plot for PET/MO copolymer………………………………………….5 1H NMR spectra for extracted samples of PET/MO copolymer…………….6 1H NMR spectra for physical blend of PET/MO…………………………….7 1H NMR spectra for extracted sample of physical blend of PET/MO……….3 Reaction analysis between PET and CHEDM using NMR spectroscopy……….1 1H NMR spectrum of pure CHEDM………………………………………….2 1H NMR spectra of PET/CHEDM copolymer……………………………….3 1H NMR spectra of physical blend of PET/CHEDM…………………………69 3.1 For WA314 PET………………………………………………………………73 3.2 For PET/MO copolymers…………………………………………………….3 For PET/CHEDM copolymers……………………………………………….1 For WA314 PET………………………………………………………………78 3.2 For PET/MO copolymers…………………………………………………….3 For PET/CHEDM copolymers……………………………………………….7 Melting and isothermal crystallization behavior of PET/scavenger copolymers………………………………………………………………………….1 Approach used to study isothermal crystallization behavior of PET/scavenger copolymers……………………………………………………….2 Equilibrium melting point……….4 Half time method…………………………….8 Microscopy of PET/scavenger copolymers……………………….9 Spherulite radii determination using SALS………………………………….10 SSP of PET/scavenger copolymers……………………………………….1 For PET/scavenger copolymers……………………………………….2 Effect of catalyst on oxygen permeability………………………………….12 Density of PET/scavenger copolymers………………………………….14 Calculation of oxygen scavenging capacity of scavengers………………….2 For 3-cyclohexene-1,1-dimethanol…………….2 Experimental determination of oxygen scavenging capacity of scavengers………………………………………………………………………….15 Effect of oxidation catalyst on rheological and thermal properties………….1 Rheological behavior of PET/scavenger copolymers………………….1 For PET/CHEDM copolymer………………………………….2 For PET/MO copolymer………………………………………….3 For WA314 PET…………………………………………….2 Thermal behavior of PET/scavenger copolymers…………………….1 DSC data for PET/MO copolymer……………………….2 DSC data for PET/CHEDM copolymer……………………….17 A methodology to determine the scavenging capacity of potential O2 scavengers……………………………………………………………………….1 Determination of oxidation kinetics of pure MO and PET/MO copolymer.2 Determination of oxidation kinetics of pure CHEDM and PET/CHEDM copolymer……………………………….3 Determination of Thiele Modulus for pure scavengers and the PET/scavenger copolymers………………………………….18 Oxidation byproducts of pure scavengers and PET/scavenger copolymers……220 3.1 Analysis of the oxidation byproducts using GC-MS………………….2 Analysis of the oxidation byproducts using GC…………………….

Conclusions and Recommendations 229 4.2 Future work/Recommendations. References 237 xii List of Figures Figure 1.1: Chemical structure of PET…………………………………………….2: Reaction of active oxygen scavenger with oxygen ………….3: Melt polymerization steps in PET and additives………………………….4: Advantage of active oxygen scavenger………………………………….5: Structures of scavengers (a) Monoolein, (b) 3-cyclohexene-1,1- dimethanol……………………………………………………………………………….1: Schematic diagram of melt polymerization reactor…………………………28 Figure 2.2: The schematic of an NMR instrument………….3: The calibration curve of melt intrinsic viscosity………….4: Schematic diagram of Buhler solid state polymerization reactor……………38 Figure 2.5: Diagram of small angle light scattering setup………………………….6: Pressure-drop (∆p) oxygen consumption test……………………………….1: Structure of PET………………….2: 1H NMR spectrum of pure PET…………………………………………….3: Structure of Monoolein (MO)……………………………………………….4: 1H NMR spectrum of pure MO in a mixture of d-TFA and d-chloroform….5: 1H NMR spectrum of PET/MO(5wt%) copolymer………………………….6: COSY plot for PET/MO(5wt%) copolymer……………………………….7: COSY plot (expanded) for PET/MO(5wt%) copolymer…………………….8: 1H NMR spectrum of PET/MO(5wt%) copolymer…………………….9: 1H NMR spectrum of PET/MO(5wt%) copolymer after extraction ……….10: 1H NMR spectra for PET/MO (physical blends)………………………….11: H NMR spectrum of pure CHEDM in a mixture of d-TFA and d- chloroform (Fresh)……………………………………………………………………….12: 1H NMR spectrum of pure CHEDM in a mixture of d-TFA and d- chloroform (After 1 day)…………………………………………………………………66 Figure 3.13: 1H NMR spectrum of PET/CHEDM(5wt%) copolymer ………………….14: 1H NMR spectrum of physical blend of PET/CHEDM ……….15: Viscosity versus shear rate for WA314 PET…….16: Viscosity versus shear rate for PET/MO copolymers…………………….17: Viscosity versus shear rate for PET/CHEDM copolymers……………….18: DSC plot for WA314 PET (heating after the quench)………………….19: DSC plot for WA314 PET (cooling from the melt)…………………….20: DSC plot for PET/MO copolymers (heating after the quench)………….21: DSC plot for PET/MO copolymers (cooling from the melt)…………….22: DSC plot for PET/CHEDM copolymers (heating after the quench)…….23: DSC plot for PET/CHEDM copolymers (cooling from the melt)……….24: DSC results from fusion of PET. The isothermal crystallization conditions were, a) 460K,b) 465K, c) 470K, d) 478K…………………………………………….25: Multiple melting peaks of isothermally crystallized WA314 PET.26: Multiple melting peaks of isothermally crystallized PET/MO(1wt%) copolymer……………………………………………………………………………….27: Multiple melting peaks of isothermally crystallized PET/MO(5wt%) copolymer……………………………………………………………………………….28: Multiple melting peaks of isothermally crystallized PET/CHEDM(1wt%) copolymer……………………………………………………………………………….29: Multiple melting peaks of isothermally crystallized PET/CHEDM(3wt%) copolymer……………………………………………………………………………….30: Multiple melting peaks of isothermally crystallized PET/CHEDM(5wt%) copolymer……………………………………………………………………………….31: Multiple melting peaks of isothermally crystallized PET/CHEDM(5wt%) copolymer……………………………………………………………………………….32: A plot used to obtain the equilibrium melting temperature (Tmo) of PET/MO(1wt%) copolymer (showing melting peaks Tm1, Tm2, Tm3) versus crystallization temperature…………………………………….33: The depression of equilibrium melting point of PET/CHEDM copolymers…………………….34: The depression of equilibrium melting point of PET/MO copolymers…….35: Crystallization behavior for isothermally crystallized PET/CHEDM(5wt%) copolymer………………………………………………………………………….36: Half time plotted as a function of crystallization temperature for isothermally crystallized WA314 PET………………………………….37: Half time plotted as a function of crystallization temperature for isothermally crystallized PET/MO copolymers…………………………………….38: Half time plotted as a function of degree of undercooling for PET/MO copolymers…….39: Half time plotted as a function of crystallization temperature for isothermally crystallized PET/CHEDM copolymers……………….40: Half time plotted as a function of degree of undercooling for PET/CHEDM copolymers…….41: θa versus ln(t) for isothermally crystallized WA314 PET.42: θa versus ln(t) for isothermally crystallized PET/MO(5wt%) copolymer………………………………………………………………………………106 Figure 3.43: θa versus ln(t) for isothermally crystallized PET/CHEDM(3wt%) copolymer………………………………………………………………………………107 Figure 3.44: ln(-ln(θa)) versus ln(t) for isothermally crystallized WA314 PET……….45: ln(-ln(θa)) versus ln(t) for isothermally crystallized PET/MO(5wt%) copolymer………………………………………………………………………………108 Figure 3.47: Microphotograph of WA314 PET spherulite growth at 200oC for 120 sec………………………………………………………………………………………116 Figure 3.48: Microphotograph of PET/MO(5wt%) spherulite growth at 200oC for 120 sec………………………………………………………………………………………116 Figure 3.49: Impurities in a) WA314 PET; b) PET/MO(5wt%) copolymer sample….50: Impurities in a) PET/CHEDM(5wt%) copolymer b) Pure CHEDM compound……………………………………………………………………………….51: Spherulite growth for WA314 PET during isothermal crystallization at 200oC………………………………………………………………………………….52: Spherulite growth for PET/MO(5wt%) copolymer during isothermal crystallization at 200oC…………………………………………………………….53: Spherulite growth for PET/CHEDM(5wt%) copolymer during isothermal crystallization at 200oC………………………………………………………….54: WA314 PET spherulite growth from the melt at 200oC.55: PET/MO(5wt%) spherulite growth from the melt at 200oC…………….56: Apparent intrinsic viscosity (dL/g) versus time (min) for PET/CHEDM(3wt%) copolymer…………………………………….57: Apparent intrinsic viscosity (dL/g) versus time (min) for PET/CHEDM(1wt%) copolymer…………………………….58: IV comparison of PET/CHEDM copolymers (before and after SSP reaction)……………………………………………………………………………….59: Oxygen permeability of PET/MO, PET/CHEDM copolymer and PET sheets……………………………………………………………………………………131 Figure 3.60: Average oxygen permeability for PET/MO copolymer and pure PET….61: Average densities versus concentration of scavenger…………………….62: Pressure of oxygen versus time of oxidation………………………….63: Shear viscosity versus shear rate for PET/CHEDM(1wt%) copolymer….64: Shear viscosity versus shear rate for PET/CHEDM(5wt%) copolymer….65: Shear viscosity versus shear rate for PET/MO(5wt%) copolymer……….66: Shear viscosity versus shear rate for WA314 PET sample……………….67: Melting and crystallization behavior for PET/MO(5wt%) copolymer samples………………………………………………………………………………….68: Crystallization behavior for PET/MO(5wt%) copolymer samples……….69: Melting and crystallization behavior for PET/MO(5wt%) copolymer samples………………………………………………………………………………….70: Crystallization behavior for PET/MO(5wt%) copolymer samples……….71: Melting and Crystallization behavior for PET/CHEDM(5wt%) copolymer………………………………………………………………………………155 Figure 3.72: Crystallization behavior for PET/CHEDM(5wt%) copolymer sample….73: Melting and crystallization behavior for PET/CHEDM(1wt%) copolymer sample………………………………………………………………………………….74: Crystallization behavior for PET/CHEDM(1wt%) copolymer sample….75: Crystallization behavior for PET/CHEDM copolymer (from glassy state).76: Crystallization behavior for PET/CHEDM copolymer (cooling from the melt)…………………………………………………………………………………….77: Structure of pure MO………………………………………………….78: FTIR spectrum of pure MO (before oxidation and after oxidation at 50oC)………………………………………………………………………………….79: Expanded FTIR spectrum of pure MO (before oxidation and after oxidation at 50oC)………………………………………………………………………….80: Expanded FTIR spectrum of pure MO (before oxidation and after oxidation at 50oC)……………………………………………………………………….81: Plot of ln(R/R(t0)) versus time for pure monoolein……………………….82: Plot of normalized height of double bond peak versus time for pure monoolein…………………………………………………………………………….83: Plot of ln(-rate) versus ln(CA) for pure monoolein………………….84: 1H NMR spectrum of pure MO (before oxidation)…………………….85: 1H NMR spectrum of pure MO (after oxidation for 8 days at 50oC)…….