Alpha-relaxation of a coal tar pitch and temperature-density effects on the viscoelastic parameters analysis

Autor:	X. Py, F. Nauguier, E. Daguerre
Rok vydání:	1998
Předmět:	Chemistry Relaxation (NMR) Thermodynamics General Chemistry Atmospheric temperature range Viscoelasticity Amorphous solid Viscosity Superposition principle Dynamic modulus medicine General Materials Science Coal tar Composite material medicine.drug
Zdroj:	Carbon. 36:1099-1105
ISSN:	0008-6223
Popis:	The alpha-relaxation of a coal tar pitch has been experimentally illustrated through typical G′ and G″ isotherms steps and tan (δ) peak isochrone. This phenomena has been identified by means of its non-Debye (m ~ 1, n ~ 0.5) and non-Arrhenius behaviours. It has been characterized in terms of its relaxation temperature Tα and relaxation time τα and compared to A240 petroleum pitch and amorphous polymers leading to a strong similarity between these materials. Moreover, experimental density data have been investigated in the temperature range of 25 to 400 °C for both petroleum and coal tar pitches using the Archimedean method. The obtained results were in very good agreement with published data based on dilatometry. The density effect on the time-temperature superposition standard procedure has been analysed in terms of reduced loss modulus and shift factors deviations. Temperature-density and temperature-viscosity data have been used for calculation of theoretical shift factors which have been compared with success to empirical ones.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_________::1f90bdbd4e4e09ceb6ca8a9975ab2b0f https://doi.org/10.1016/s0008-6223(98)00083-9 Zobrazit plný text záznamu Full Text from ScienceDirect