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X-ray structural analysis of the thermotropic copolyesters Xyda(registered trademark) and Vectra(registered trademark)

Cheng, Hsiao-Mo
http://rave.ohiolink.edu/etdc/view?acc_num=case1054757724

Abstract Details

1990, Doctor of Philosophy, Case Western Reserve University, Macromolecular Science.
In this thesis, attention is focussed on the copolyesters prepared from p-hydroxybenzoic acid, terephthalic acid, and biphenol; and from p-hydroxybenzoic and 2-hydroxy-6-naphthoic acid. The chemical formulations of these copolymers are the bases for the Xydar°ler and Vectra°ler family of commercial resins, respectively. X-ray fiber diagrams for Xydar°ler show the meridional region contains a series of aperiodic maxima that shift in position with the composition. These are reproduced in predictions of the scattering intensity for a nematic array of chains of completely random monomer sequence. The results of the point and atomic models are in good agreement, which is further improved when the effect of chain nonlinearity is incorporated. A model with nonrandom sequence distributions shows all but minimal blockiness can be ruled out by the x-ray data. The positions of the meridionals are unaffected by annealing, and hence the annealing does not affect the monomer sequence. The fiber diffraction patterns of Vectra°ler change considerably as a result of annealing. Two additional meridionals appear on annealing. The meridional intensity at d = 3.33 A is not generated for models consisting of registered array of chains of completely r andom monomer sequence. However, the observed meridionals are generated in calculations for monomer sequence with a slight alternating tendency. Calculation of the cylindrically averaged intensity transforms shows very good agreement between the observed and calculated layer line positions for this degree of nonrandomness. The equatorial reflections that develop for Vectra°ler during annealing indicate a change in the chain packing. The structural changes between as-spun and annealed copolymer are similar to the polymorphic changes reported for homopoly(p-hydroxybenzoate). The annealed structure has a more tightly packed structure, in which the chain has a pseudo 21 helical conformation. The DSC data correlate well with the observed structural changes due to annealing.
John Blackwell (Advisor)
144 p.
Plastics Technology
X-ray structural analysis thermotropic copolyesters Xyda Vectra

Recommended Citations

Citations

  • Cheng, H.-M. (1990). X-ray structural analysis of the thermotropic copolyesters Xyda(registered trademark) and Vectra(registered trademark) [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1054757724

    APA Style (7th edition)

  • Cheng, Hsiao-Mo. X-ray structural analysis of the thermotropic copolyesters Xyda(registered trademark) and Vectra(registered trademark). 1990. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1054757724.

    MLA Style (8th edition)

  • Cheng, Hsiao-Mo. "X-ray structural analysis of the thermotropic copolyesters Xyda(registered trademark) and Vectra(registered trademark)." Doctoral dissertation, Case Western Reserve University, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=case1054757724

    Chicago Manual of Style (17th edition)

case1054757724
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© 1990, all rights reserved.
This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.