화학공학소재연구정보센터
Macromolecules, Vol.27, No.8, 2092-2101, 1994
Correlations of Relaxing Dipole Entities and Conductivity Effects on Model Compounds and Molecular Chains with 2-Chlorocyclohexyl Esters in Their Structure
The temperature and frequency dependence of the complex dielectric permittivity epsilon* for both 2-chlorocyclohexyl isobutyrate (CCHI) and poly(2-chlorocyclohexyl acrylate) (PCCHA) is reported. The polymer exhibits an ostensible beta relaxation, centered at -60-degrees-C at 5 Hz, whose activation energy at constant frequency seems to increase with temperature followed by a glass-rubber relaxation or a process, centered at 70-degrees-C at 5 Hz, in which conductive processes become dominant at low frequencies. The model compound only exhibits a glass-liquid relaxation whose maximum is located at -92-degrees-C at 1 Hz. The analysis of the dielectric results in terms of the electric modulus suggests that whereas the conductive processes in CCHI are produced only by free charges, the conductivity observed in PCCHA involves both free charges and interfacial phenomena. The experimental intramolecular dipolar correlation g(intra) is somewhat larger than 1 for both CCHI and PCCHA, suggesting that correlations of orientation enhance the polarity of these systems. A 4 X 4 rotational states scheme which accounts for two rotational states about the CH-CO bonds of the side group reproduces very satisfactorily the intramolecular correlation coefficient of the polymer. Finally, the critical interpretation of the dielectric results obtained in the bulk indicates that intermolecular dipolar interactions do not play a significant role in the dielectric behavior of these systems.