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The Effect of Biobased Comonomers (Isosorbide and 2,5-furan dicarboxylic acid) on Alkaline Hydrolysis of Co-polyesters, PEIxT and PETFy

Das, Ananya
http://rave.ohiolink.edu/etdc/view?acc_num=toledo1620236151935524

Abstract Details

2021, Master of Science, University of Toledo, Chemical Engineering.
Two bio-based comonomers, isosorbide (ISB) and 2,5-Furan dicarboxylic acid (FDCA) was used to partially or completely replace the diol, Ethylene glycol (EG) or diacid, Terephthalic acid (TPA) of petroleum-based polyester, Polyethylene terephthalate (PET). The effect of the co-monomers on the alkaline hydrolysis reaction of bio-based co-polyesters, PEIxT and PETFy or polyester, Polyethylene furanoate (PEF) was investigated to compare the rate of depolymerization for their reaction kinetics and the factors contributing to the reaction mechanism were studied. Different compositions of ISB (3%, 8% and 12%) was used to replace the EG in PET to produce the PEIxT co-polyesters and different composition of FDCA (10% and 100%) was used to replace the TPA to produce the PETFy co-polyesters. The 100% replacement of TPA with FDCA, produced the furan analogous of PET, PEF. The alkaline hydrolysis reaction kinetics were studied at temperatures between 130oC-150oC in 1.1 M Sodium Hydroxide (NaOH) solution in a glass reactor system and a Parr reactor system. The comonomers exhibited increase in the reaction rates under alkaline hydrolysis relative to the pure PET for all systems. Since alkaline hydrolysis occurs in the amorphous region near the surface of the polymers, the crystallinity, surface wetting and water uptake properties of the polymers have an impact on the hydrolysis reaction kinetics. To understand the cause for the improved reaction kinetics with inclusion of the co-monomers, the impact of comonomers on the physical properties such as crystallinity, surface wetting and water uptake were studied. The reactive bonds of the co-monomers can have a significant impact on the ester linkage in the co-polyesters that make them susceptible to hydrolytic degradation. Literature on the hydrolytic degradation in the environment suggests that the ester-linkage of isosorbide with TPA might be more susceptible to hydrolysis than the linkage of EG with TPA, which could be a factor in facilitating the hydrolysis reaction at lower temperatures. Similarly, the FDCA-EG linkage could be more reactive under hydrolysis than the EG-TPA bond. To compare the reactivity of the ester linkage of the oxygen-based furan rings of FDCA to the aromatic benzene ring of TPA, the reaction kinetics of small molecule analogues, Bis (2-hydroxyethyl) terephthalate (BHET) for PET and Bis-hydroxyethyl 2,5-Furandicarboxylate (BHEF) for PEF were compared. To determine the reaction rate constants of the PEIxT co-polyesters, the conversion rates at 130°C were fit into an established first order kinetic model. Because of the higher reaction rates of the PETF10 and PEF at the experimental temperatures studied (130°C -150°C), the kinetics of the samples could not be captured. Fourier Transform Infrared Spectroscopy (FTIR) was used to analyze the precipitate following filtration of the co-polymers from product of the alkaline hydrolysis reactions. FTIR data confirmed the presence of functional groups consistent with monomers present in the co-polyesters qualitatively. Proton (1H) and Carbon (13C) Nuclear Magnetic Resonance (NMR) was also performed on the co-polyester samples to quantify the monomers present in the samples. A recovery method for the co-monomers, TPA and FDCA based on selective solubility of TPA and FDCA in water and dimethyl sulfoxide (DMSO) co-solvent system was investigated. The solubility of TPA and FDCA in water is limited, but in DMSO, TPA has a19 wt% solubility and FDCA has a 55 wt% solubility at room temperature. Preliminary work demonstrated that using the difference in their solubility in the DMSO solvent, TPA can be selectively precipitated from the TPA/FDCA mixture in DMSO using water as an anti-solvent, however, further studied need to be done for the recovery of FDCA from the FDCA/DMSO solution. Since, isosorbide is readily soluble in water, the isosorbide following the alkaline hydrolysis of PEIxT co-polyesters were expected to be washed off with water in the EG/water residue, during washing of the recovered product. Literature suggests a distillation and cold-crystallization method can be used as an energy optimized isosorbide recovery method from a EG/water solution. Bio-based co-polyesters exhibited higher reaction rates compared to PET, while PEF exhibited the highest reaction rate at all temperatures. The impact of the co-polyesters on crystallinity, surface wetting, water uptake and the bond reactivity could be facilitating the higher reaction rates. TPA following the alkaline hydrolysis of PETFy can be recovered using the selective solubility of TPA and FDCA in a co-solvent of DMSO and water. ISB can be recovered from the residue solution of EG and water using a distillation and cold crystallization method.
Maria Coleman, Dr. (Committee Chair)
191 p.
Chemical Engineering
Alkaline hydrolysis; PET; Copolyesters; isosorbide; FDCA; degradability; Co-solvents; Co-monomer separation

Recommended Citations

Citations

  • Das, A. (2021). The Effect of Biobased Comonomers (Isosorbide and 2,5-furan dicarboxylic acid) on Alkaline Hydrolysis of Co-polyesters, PEIxT and PETFy [Master's thesis, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1620236151935524

    APA Style (7th edition)

  • Das, Ananya. The Effect of Biobased Comonomers (Isosorbide and 2,5-furan dicarboxylic acid) on Alkaline Hydrolysis of Co-polyesters, PEIxT and PETFy. 2021. University of Toledo, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=toledo1620236151935524.

    MLA Style (8th edition)

  • Das, Ananya. "The Effect of Biobased Comonomers (Isosorbide and 2,5-furan dicarboxylic acid) on Alkaline Hydrolysis of Co-polyesters, PEIxT and PETFy." Master's thesis, University of Toledo, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1620236151935524

    Chicago Manual of Style (17th edition)

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