Advanced thermal analysis of fluorinated and chlorinated polyethylenes

Abstract

The heat capacities of the above polymers in the solid state are analysed by separating skeletal contributions (described by the Tarasov function) and group contributions (described by Einstein and box distribution functions). A prediction scheme which can be used also for copolymers or blends, is developed. The parameters of the Tarasov function 0₁, 0₃ are given from the equations: 0₁*m½=2790 and 0₃*m½=540. The group contributions can be found by forming the appropriate average of the group contributions of a few polymers and those are given in tabulated form in the thesis.

Poly(vinylidene fluoride) and polytrifluoroethylene are investigated by thermal analysis. The transitions are in agreement with the results of various methods found in the literature. These results can be interpreted with the assumption of a conformationally disordered (C.D.) crystal and a C.D. glass. For the first time a C.D. glass to C.D. crystal transition is proposed at about 360 K for poly(vinylidene fluoride) and at about 250 K for polytrifluoroethylene. New glass transitions are proposed for poly(vinylidene fluoride) at 212 K and for polytrifluoroethylene at 280 K.

Thermodynamic functions of the above halogenated polyethylenes are tabulated.

A method is presented to predict heat capacities and other thermodynamic properties of any polymer in the liquid state. The partition function is separated in three parts: a vibrational, a configurational due to intermolecular interactions, and a conformational due to intramolecular interactions. For the first time, agreement between calculation and experiment was possible

Liquid heat capacities of the fluorinated polymers are found to be nonlinear. An empirical addition scheme is developed. The heat capacity can be described by two linear equations one above and the other below 480 K.

This thesis deals with the thermal properties of halogenated polyethylenes.