Cure kinetics and thermodynamics of polyurethane network formation based on castor oil based polyester polyol and 4,4’-diphenyl methane diisocyanate

• Published in: Indian journal of chemical technology 2021-05, Vol.28 (3), p.336
• Main Authors: Balakrishnan, Remya, Varghese, Lity Alen, Manu, S K
• Format: Article
• Language: English
• Subjects: Accumulation; Activation energy; Castor oil; Curing; Diphenyl methane diisocyanate; Enthalpy; Entropy; Entropy of activation; Equivalence; Evaluation; Free energy; Isocyanates; Kinetics; Methane; Network formation; Parameters; Polyesters; Polymerization; Polyurethane; Polyurethane resins; Reaction kinetics; Viscosity
• ISSN: 0971-457X; 0975-0991
• DOI: 10.56042/ijct.v28i3.30562

In this work, isothermal curing kinetics of a non-catalysed and non-blown reaction between castor oil based polyester polyol and polymeric 4, 4'-diphenyl methane diisocyanate (MDI) has been investigated using Differential Scanning calorimeter (DSC) and viscosity build up studies. Several phenomenological models like Ozawa, Kissinger and Kissinger- Akahira-Sunose (KAS) isoconversional methods has been adopted to study polymerisation kinetics through DSC. DSC cure kinetics is studied at different heating rates (5°C/min, 10°C/min, 15°C/min and 20°C/min). Viscosity build up studies are also done for evaluating the kinetic parameters. These studies have been conducted for an isocyanate index [NCO equivalents/OH equivalents] of 1:1 and 1:2. Dynamic viscosity is measured as a function of time and rate constant and activation energy of the curing system is evaluated. Activation energy obtained for 1:1 index through Ozawa and Kissinger methods is found to be in the range of 70kJ/mol and for 1:2 index it is found to be in the range of 50kJ/mol. Thermodynamic parameters like Gibb's free energy (Activation Free Energy), activation enthalpy and activation entropy of the polymerisation kinetics is calculated using Wynne-Jones-Eyring-Evans Theory.