Electrochemically initiated cationic polymerization of trioxane in acetonitrile. Part I

Abstract

Trioxane, dissolved in acetonitrile solvent containing tetrabutylammonium perchlorate as background electrolyte, has been polymerized under continuous current supply at the anode of an electrolytic cell with separated anodic and cathodic compartments. The polymerization rate and the molecular weight of the polymers obtained are functions of the current intensity and the reaction temperature.At 20°C the reacting system presents a poor autocatalytic trend and may be described by the hypothesis of the steady state for the active species.The thermal stability of the polyoxymethylenes obtained in acetonitrile solvent is improved by the electrochemical copolymerization of trioxane with 1,3-dioxolane. ZUSAMMENFASSUNG:Trioxan, gelost in Acetonitril, das Tetrabutylammoniumperchlorat als Leitsalz enthielt, wurde an der Anode einer elektrolytischen Zelle, bei der Anodenraum und Kathodenraum getrennt waren, unter kontinuierlicher Stromzufuhr polymerisiert. Die Polymerisationsgeschwindigkeit und das Molekulargewicht der entstandenen Polymeren sind Funktionen der Stromstirke und der Reaktionstemperatur.Bei 20 O C zeigt das Reaktionssystem eine schwach autokatalytische Tendenz und kann unter Annahme eines Gleichgewichtszustandes fiir die aktiven Spezies beschrieben werden.Die thermische Stabilitat des Polyoxymethylens, das in Acetonitril als Losungsmittel erhalten wurde, wird durch die elektrochemische Copolymerisation des Trioxans mit 1,3-Dioxolan verbessert.

Electrochemically initiated cationic polymerization of trioxane in benzonitrile and nitrobenzene. Part II

“…Under the applied conditions, the autocatalysis does not seem to be due to an increased number of active species because of their strong dependence onQ*. On the other hand, the termination reactions occurring in benzonitrile and acetonitrile (see Part I) 4), correspond to copolymerization reactions or to a degradative chain transfer to the solvents. They are not intrinsic for the cationic polymerization of TR.…”

The Logarithmic Ear: Pietro Mengoli's Mathematics of Music

“…This information is tabulated for every musical interval. 94 This would seem to tie each interval to a small number of different pitch levels at which it can be perceived: but in fact tensing or slackening of the tympani to alter their natural frequencies allows each interval to be heard at a continuous range of different pitches. 95 Next, he argued that if a heard interval is not a consonance, but is close to one, the tympanum would be be tensed so as to make the interval into a true consonance.…”