Polyoxymethylene from trioxane by solid state polymerization: A case of twinning in a synthetic polymer

Abstract

The products obtained by sublimation or radiation of trioxane by high energy radiations have been examined by X-ray diffraction analysis.It has been possible to demonstrate that they consist of twinned crystals of hexagonal polyoxymethylene. By using rotating and WEISSENBERG photographs, the geometric correlations between the elements of the twins have also been definitely established. ZUSAMMENFASSUNG:Durch Analyse von Rontgendiagrammen werden die Produkte uutersucht, die bei Sublimation oder Bestrahlung von Trioxan mit energiereiehen Strahlen entstehen.Man kann zeigen, daf3 diese Produkte aus Zwillingskristallen von hexagonalem Polyoxymethylen bestehen. Mit Hilfe von Drehkristall-und WEISSENBERG-Aufnahmen konnen die geometrischen Beziehungen zwischen den Zwillingselementen gesichert werden. c y-3.563 A and helicoidal chains of the 211 type12). 171 G. CARAZZOLO, S. LEGHISSA, and M. MAMMIBoth structure analyses of these POM modifications were carried out by using X-ray diagrams of powders or stretched fibers.On the contrary, X-ray diffraction patterns of the single-crystal type are shown by POM when it is formed either by repeated sublimations of trioxane (first obtained by HAMMICK and B O E R E E~~) in 1922) or from radiation of trioxane with high energy radiations (HER) (prepared in 1961 by HAYASHI et al.I4)).

The polymerization of crystalline trioxane. IV. the spontaneous polymerization

“…The high degree of crystallographic and morphologic order of the polymer, and its specific orientation relation with the parent monomer crystals (Carazzolo et al 1963, Staudinger et al 1927, Kohlschutter 1930 Kohlschutter and Sprenger 1932), though in principle compatible also with an epitactic mechanism, are consistent with this conclusion.…”

“…Hammick and Boeree (1922) were the first to describe how sublimation of dry trioxane in vacuum produced a new ' polymeride ' of formaldehyde :…”

Structural Refinement and Extraction of Hydrogen Atomic Positions in Polyoxymethylene Crystal Based on the First Successful Measurements of 2-Dimensional High-Energy Synchrotron X-ray Diffraction and Wide-Angle Neutron Diffraction Patterns of Hydrogenated and Deuterated Species

“…12,13 The thusobtained POM samples contained some portions of twin structures. 13,20,21 These twin structures could be erased almost perfectly by heating the original sample at 170 C for 5 h. In case of POM-h 2 , the sample was relatively easily thermally decomposed and it became thinner after a long heat treatment. In contrast, the POM-d 2 was found to keep the original size relatively stably even when heated up to high temperature.…”

The polymerization of crystalline trioxane. I. evidence for a cooperative mechanism

“…It polymerizes in the solid state during or after irradiation by x-rays Hayashi 1961, 1962, Okamura et d. 1962, Busetti et ul. 1962, 1963, Carazzolo et al 1963, Lando et al 1962, Hayashi et al 1964, Pshezhetskii et al 1964, Nauta 1965 van der Heijde et al 1965). Not merely in the radiation-induced polymerization, which definitely requires crystalline monomer, but also in the spontaneous reaction and even in the acid-catalysed polymerization, monomer crystallinity appears to be unusually important (Celanese Cory).…”