Degradation kinetics of polyol
| Autor: | Hans Raj, Dhirendra Nigam, G. N. Mathur |
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| Rok vydání: | 1989 |
| Předmět: | |
| Zdroj: | Journal of Propulsion and Power. 5:561-564 |
| ISSN: | 1533-3876 0748-4658 |
| Popis: | The degradation kinetics of Isro-Polyol, a propellaiit binder, were studied by dynamic thermogravimetry at different heating rates in nitrogen atmosphere. The experimental data indicate polyol decomposition follows a three-step reaction mechanism. The order of reaction for each step was calculated using a differential method and an integral method. The order of reaction for each step was found to be 2, 2/3, and 1, respectively. Kinetic parameters, viz., activation energy and pre-exponential factor, were calculated for each step by using the methods of referenced authors. OLYURETHANE binder systems capable of giving a variety of composite propellant result from the reaction of the hydroxyl terminated polyether prepolymers with di- isocyanate. This type of binder system, based on hydroxy terminated poly butadiene (HTPB) and saturated polyester, are considered to be workhorse systems as solid fuel in rockets. They have been used in different motors of various stages of rockets and satellite launch vehicles in France, India, and the U.S. Isro-Polyol-based polymeric fuel binder has been developed by the Indian Space Research Organisation. This polyol, which is derived from castor oil,1 exhibits comparable energet- ics and mechanical properties to the widely used HTPB-based propellants. However, Isro-Polyol propellants have a lower burning rate compared to HTPB-based propellants with equal solids content.2 It has been shown that thermal decomposition of polymeric fuel binders demonstrate an important role in combustion of solid propellants.3'4 Thermogravimetry (TG) has been used for several years to study the degradation phenomenon of polymers. General reviews on the TG of polymers include those by Chiu,5 Anderson,6 Reich and Levi,7 Zimmerman and Budisch,8 Reich,9 and Reich and Stivala.10 The kinetic studies of polymer degradation by isothermal and dynamic TG meth- ods have been compared,11 and kinetic studies by TG have been reviewed.12-13 Applications best suited to TGA tech- niques include thermal stability of materials, compositional analysis of multicomponen t systems, kinetic studies, moisture and volatiles determinations, accelerated aging tests, and oxi- dation-reduction reactions.14 Varney and Strahle15 and Ninan and Krishnan16 studied thermal decomposition kinetics of polybutadiene binders. The effect of procedural factors on kinetic parameters (energy of activation E and pre-exponen- tial factor A) calculated from TG curves were also studied.16 In this investigation, an attempt has been made to study the degradation kinetics of Isro-Polyol at different heating rates to derive its thermokinetics. |
| Databáze: | OpenAIRE |
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