Premium
Calorimetric study of tetramethylene urethane and of poly(tetramethylene urethane) between 0 and 300 K
Author(s) -
Lebedev Boris V.,
Bykova Tat'yana A.,
Kiparisova Elena G.,
Kochetkov Alexander M.,
Höcker Hartwig,
Kusan Jacqueline,
Keul Helmut
Publication year - 1999
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/(sici)1521-3935(19990801)200:8<1863::aid-macp1863>3.0.co;2-d
Subject(s) - isothermal process , heat capacity , polymerization , polymer , chemistry , polymer chemistry , thermodynamics , calorimeter (particle physics) , adiabatic process , atmospheric temperature range , gibbs free energy , monomer , limiting , standard enthalpy of formation , organic chemistry , physics , engineering , mechanical engineering , detector , optics
In an adiabatic vacuum calorimeter the temperature dependence of the heat capacity C p 0 of tetramethylene urethane (TMU) (2‐oxo‐hexahydro‐1,3‐oxazepine) and poly(tetramethylene urethane) (PTMU) was studied between 4.3 and 300 K with an uncertainty of about 0.2%. In a calorimeter with a static bomb and an isothermal shield the energies of combustion Δ U comb of the monomer and the polymer were measured. From the experimental data the thermodynamic functions C p 0 , H 0 ( T )– H 0 (0), S 0 ( T ), G 0 ( T )– H 0 (0) were calculated in the range of 0 to 300 K, and enthalpies of combustion Δ H 0 comb and thermochemical parameters of formation Δ H 0 f , Δ S 0 f , Δ G 0 f of TMU and PTMU were estimated at T = 298.15 K and standard pressure. The results obtained were used to calculate the thermodynamic characteristics of TMU polymerization in bulk (Δ H 0 pol , Δ S 0 pol , Δ G 0 pol ) with opening of the seven‐membered ring and formation of the linear polymer PTMU, in the range of 0 to 300 K. It was found that the values of the standard Gibbs function of the process (Δ G 0 pol = (–41)–(–42) kJ·mol –1 ) are always negative and do not substantially depend upon temperature in the whole temperature interval studied. This implies that the equilibrium TMU ⇄ PTMU is far on the side of the polymer. The upper (ceiling) limiting temperature of TMU polymerization is T 0 ceil > 1 000 K.