ROLE OF FILLER PARTICLE SIZE IN THE FORMULATION OF COMPOSITE SOLID PROPELLANT

Abstract

Formulation of poly(vinyl chloride), PVC - ammonium perchlorate, AP, composite solid propellant has been accomplished in the light of different compositional variables such as plasticizer composition, particle size of AP and anticaking agent / burn rate accelerators. It has been found that the mixed plasticizer DOP3S1 [containing 75v% DOP, (dioctyl phthalate), and 25v% DOS, (dioctyl sebacate)] is the most suitable plasticizer for PVC resin at least for the present study. The rheological study of PVC – DOP3S1 plastsol shows that the system unequivocally behaves as a pseudoplastic thixotrope at least up to a storage time of 49 hours. The degree of thixotropicity, however, shows a decreasing trend beyond this period. The rheological studies on virgin and aluminized propellants have been seen to follow the similar trend. The magnitude of apparent viscosity in the former case is seen to be many fold higher than those of plastisols whereas that of metallized propellants although also higher than plastisols but is found to be less than those of virgin compositions. The porosity data for unimodal AP as a function of mean particle diameter has been found to vary linearly whereas coarse – fine AP blends show minimum porosity in the range of 30wt% – 33 wt% fine AP content which is substantiated by density and ambient burn rate data.