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Vibrational, crystallographic, and mechanistic studies of benzoxazine monomers and their resulting polybenzoxazines as novel phenolic resins

Dunkers, Joy Patricia
http://rave.ohiolink.edu/etdc/view?acc_num=case1058880772

Abstract Details

1994, Doctor of Philosophy, Case Western Reserve University, Macromolecular Science.
This work focuses on obtaining a fundamental understanding of a new class of phenolic resins derived from 3,4-dihydro-2H-1,3-benzoxazine monomers. In the past, the vibrational assignments of benzoxazine monomers and their resulting polymers were not well understood. For this study, model compounds of benzoxazine monomer and dimer are synthesized. Vibrational assignments of a series of 3-alkyl-3,4-dihydro-6-methyl-2H-1,3-benzoxazine monomers are made by analysis of their infrared and Raman spectra. The linear amine group is varied from methyl to amyl which alters the position of the peaks resulting from the benzoxazine ring but has little influence on the benzene ring vibrations. To aid in peak assignments, 3,4-dideutero-3,6-dimethyl-2D-1,3-benzoxazine is also synthesized. The compound N,N-bis(3,5-dimethyl-2-hydroxybenzyl)methylamine is synthesized as a dimer. Vibrational assignments of N,N-bis(3,5-dimethyl-2-hydroxybenzyl)methylamine are made by the analysis of the infrared and Raman spectra of dimer. In addition, the hydrogen groups in the methylene bridge structure are deuterated to provide insight into vibrations due to the presence of the Mannich bridge structure. The X-ray crystal structure of 3,4-dihydro-6-metho xy-3-methyl-2H-1,3-benzoxazine is presented. A mechanism of ring opening polymerization of 3-6 disubstituted benzoxazines that differs fundamentally from the mechanism already in the literature is proposed. The X-ray crystal structure of N,N-bis(3,5-dimethyl-2-hydroxybenzyl)methylamine as a model dimer for benzoxazine based phenolic resins is presented, and a hydrogen bonding scheme involving both inter and intra molecular hydrogen bonding is proposed. Hydrogen bonding of this model dimer is further studied with infrared spectroscopy in crystalline, quenched, and molten phases as well as in solution. Methyl functional trimers are built using molecular modeling software and are based on the preferred dimer conformations. The polymerization of 3,4-dihydro-3,6-dimethyl-2H-1,3-benzoxazine using strong and weak carboxylic acids and phenols as catalysts has been studied using infrared spectroscopy. The auto-accelerated curing using sebacic acid as catalyst is further documented using 1H nuclear magnetic resonance spectroscopy and dielectric analysis. Side reactions leading to termination or curing using a strong acid catalyst or no catalyst are discussed
Hatsuo Ishida (Advisor)
154 p.
Chemistry, Polymer
Benzoxazine monomers; Polybenzoxazines; Phenolic resins

Recommended Citations

Citations

  • Dunkers, J. P. (1994). Vibrational, crystallographic, and mechanistic studies of benzoxazine monomers and their resulting polybenzoxazines as novel phenolic resins [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1058880772

    APA Style (7th edition)

  • Dunkers, Joy. Vibrational, crystallographic, and mechanistic studies of benzoxazine monomers and their resulting polybenzoxazines as novel phenolic resins. 1994. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1058880772.

    MLA Style (8th edition)

  • Dunkers, Joy. "Vibrational, crystallographic, and mechanistic studies of benzoxazine monomers and their resulting polybenzoxazines as novel phenolic resins." Doctoral dissertation, Case Western Reserve University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=case1058880772

    Chicago Manual of Style (17th edition)

case1058880772
812
© 1994, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.