The thermal degradation of certain trioxane-dioxolane copolymers obtained with boron trifluoride-acrylonitrile complex as initiator has been investigated. The thermal stability of samples, discussed in terms of topoenergetic values, was relsted both to copolymer composition and conversion. The most thermostable copolymers (-5% weight loss at 300°C in air), having 5-8% dioxolane units, had the highest intrinsic viscosity in the series and were isolated at 3550% conversion. The results obtained were compared with similar data for a commercial trioxane-ethylene oxide copolymer containing 95% formal units..
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Abstract. Main topoenergetic principles are reviewed in view to emphasize the UNIVERSAL relationships between time conversion of a system in transformation and one of its governing potentials. It results that: (i) any quantity can be calibrated in unit of time and (ii) any quantity can be calibrated by another one.
Short history of topoenergetic principlesTopoenergetic principles were initiated by calorimetric studies of polyethylene morphologies created by different thermal, mechanical and/or chemical treatments [1,2]. The basic observation was that all systems in transformation have composite structure because at least two components interact between them and exchange energy (heat) with the surrounding medium ( Figure 1). Calorimetry was the most appropriate analytical technique allowing development of topoenergetic principles [1,3]. In view to quantitatively describe the kinetics of the transforming process by its components, I considered the energy circuit in similar terms like electric circuits, i.e. as composed by components with elementary behaviours: resistors, capacitors, energy sources, etc. This idea was launched in the same period of time by Oster and Auslander [4], but unfortunately they considered on the one hand very complicated cases and on the other hand that these components are spatially distributed in the transforming system. In this way mathematical description became unrealistic.The first kinetic equation established in topoenergetic terms was a modified Arrhenius equation applied for crystallization of polyethylenes by using a so called "drop calorimetry" [5]. The experimental principle of this technique consists in keeping first the calorimetric cell with the specimen at a temperature over melting point, Tm, and dropping it in the calorimeter already prepared at crystallization temperature, T. Two exothermal flows appear, namely: one immediately at the contact with calorimeter (at time considered zero) given by inert component, Cin, denoted as win, and the flow delayed at a specific time, ti, given by component in transformation, Ctr (wtr), in this case the phase which crystallizes. The kinetic equation is: ln(ti*T) = -E / (R*T) + Kwhere E -activation energy, R -the gas constant, T in Kelvin and the free term
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