Contribution à l'étude de la structure des polytéréphtalates de quelques polyméthylèneglycols

Abstract

RGSUMJ?L'Ctude des domaines cristallins au moyen de la diffraction des rayons X de fibres CtirCes bien cristallisCes a montrC que les polytCrCphtalates d'Cthykneglycol (la), de butanediol-1,4 (lb), de pentanediol-1,5 (lc) et d'hexanediol-1,6 (Id) cristallisent dans le systkme triclinique. L'evolution des param2tres ne se fait pas rCgulierement en fonction de la longueur du motif monombre. La connaissance du rCseau cristallin et de la structure chimique nous a conduit A proposer des conformations permettant aux chaines de s'arranger dans le rCseau et de proposer ainsi des hypothhes de structure pour les polyesters CtudiCs.Ces rCsultats sont confirm& par l'examen des spectres IR des Cchantillons cristallins qui presentent des bandes CaractCristiques de conformation trans tres importantes pour les polyesters l a et Id alors que les polyesters l b et lc presentent des bandes de structure gauche importantes. L'Ctude du taux de cristallinitC par differentes mCthodes (rayons X, calorimCtrie differentielie, spectres IR et colonne 2 gradient de densite) confirme la valeur proposCe pour le volume de la maille du polyester Id. SUMMARY:The study of the crystalline regions by means of X-ray diffraction of highly crystalline, drawn fibres, showed that the polyterephthalates from ethylene glycol (la), 1,4-butanediol (lb), 1,s-pentanediol (lc) or from 1,6-hexanediol (Id) crystallised in the triclinic system. The change of parameters is not a regular function of the length of the monomeric unit. The knowledge of the crystalline network and the chemical structure leads us to propose that the conformations allow the chains to rearrange themselves in the network, and so to suggest possible structures for the polyesters studied. The results were confirmed by IR spectroscopy of the crystalline samples which give strong characteristic bands indicating trans conformation for the polyesters l a and Id whereas the polyesters l b and l c give strong bonds corresponding to a gauche

Synthesis and Thermal Characterization of Poly(alkylene 2,6-anthracenedicarboxylate)s

“…P6T has multiple crystal forms, and the relative amounts of these change depending upon thermal history. [10,11] Examination of the anthracene-containing materials with a polarized light microscope shows no indication of birefringence. Thus, we have no evidence for the formation of liquid crystalline phases.…”

Structure of 2,5-hexanediyl dibenzoate

“…The 'tetramethylene' part of the molecule shows a gauchetrans-gauche conformation, while the conformation of the chain starting from C(1) to C (15) A considerable number of papers have appeared reporting crystalline structures of poly(tetramethylene terephthalate) both in a and fl forms (Mencik, 1975;Joly, Memoz, Douillard & Vallet, 1975;Desborough, 1976;Hall & Pass, 1976;Yokouchi, Sakakibara, Chatani, Tadokoro, Tanaka & Yoda, 1976) while two deal with monomers (Palmer & Brisse, 1981;Bocelli & Grenier-Loustalot, 1982). Also, a comparison between the structures of the polymer already published was examined in detail (Desborough & Hall, 1977;Hall, 1980).…”

Structures of Two Crystalline Forms of Poly(butylene terephthalate) and Reversible Transition between Them by Mechanical Deformation

“…Sci., 15,339 (1975); (b) T. K. Kwei, T. Nishi, and R. F. Roberts, Macromolecules, 7,5,667 (1974). (5) W. Heller and A. C. Thompson, J. Colloid Sci., 6,57 (1951). (4) J. R. Millar, J. Chem.…”