Thermodynamic and kinetic behaviour of salicylsalicylic acid |
| |
Authors: | Digo Hermínio P Pinto Susana S Moura Ramos Joaquim J |
| |
Institution: | (1) Centro de Química Estrutural, Complexo I, IST Av. Rovisco Pais, 1049-001 Lisboa, Portugal E-mail |
| |
Abstract: | The thermal behaviour of salicylsalicylic acid (CAS number 552-94-3) was studied by differential scanning calorimetry (DSC).
The endothermic melting peak and the fingerprint of the glass transition were characterised at a heating rate of 10°C min-1. The melting peak showed an onset at T
on = 144°C (417 K) and a maximum intensity at T
max = 152°C (425 K), while the onset of the glass transition signal was at T
on = 6°C. The melting enthalpy was found to be ΔmH = 28.9±0.3 kJ mol-1, and the heat capacity jump at the glass transition was ΔC
P = 108.1±0.1 J K-1mol-1. The study of the influence of the heating rate on the temperature location of the glass transition signal by DSC, allowed
the determination of the activation energy at the glass transition temperature (245 kJ mol-1), and the calculation of the fragility index of salicyl salicylate (m = 45). Finally, the standard molar enthalpy of formation of crystalline monoclinic salicylsalicylic acid at T = 298.15 K, was determined as ΔfHm
o(C14H10O5, cr) = - (837.6±3.3) kJ mol-1, by combustion calorimetry.
This revised version was published online in August 2006 with corrections to the Cover Date. |
| |
Keywords: | DSC enthalpy of formation supercooled liquids fragility glass forming liquid combustion calorimetry salsalate |
本文献已被 SpringerLink 等数据库收录! |
|