Vikram Sarabhai Space Centre

About: Vikram Sarabhai Space Centre is a facility organization based out in Thiruvananthapuram, India. It is known for research contribution in the topics: Aerosol & Ultimate tensile strength. The organization has 2092 authors who have published 3058 publications receiving 47975 citations. The organization is also known as: VSSC.

Effect of nanoclay on the mechanical, dynamic mechanical and thermal properties of cyanate ester syntactic foams

Abstract: Nanoclay reinforced, cyanate ester-based syntactic foams with varying nanoclay loadings were processed and evaluated for mechanical, dynamic mechanical and thermal properties. The volume percentage of the filler (microballoon + nanoclay) was kept constant at 70. X-ray diffraction studies showed intercalated morphology of the nanoclay particles in the foam composites. The properties of the nanoclay reinforced syntactic foams were compared with those of bare cyanate ester syntactic foams containing the same filler concentration. A considerable improvement in the mechanical properties viz. tensile, flexural and compressive strengths and corresponding moduli was observed for the foams on incorporation of nanoclay. The corresponding specific properties also showed substantial improvement. Nanoclay improved the toughness of the foam composites. The storage moduli were higher for the foam composites containing nanoclay. However, nanoclay diminished the Tg of the syntactic foams due to the plasticizing effect of the organic moiety of the nanoclay. The thermal properties of the syntactic foams were not significantly influenced by the addition of nanoclay.

Burning‐rate enhancement of a high‐energy rocket composite solid propellant based on ferrocene‐grafted hydroxyl‐terminated polybutadiene binder

Abstract: Four different samples of ferrocene-grafted hydroxyl-terminated polybutadiene (Fc-HTPB), containing 0.20, 0.52, 0.90, and 1.50 wt % iron, were synthesized by the Friedel–Crafts alkylation of ferrocene with hydroxyl-terminated polybutadiene (HTPB) in the presence of AlCl3 as a (Lewis acid) catalyst. The effects of the reaction conditions on the extent of ferrocene substitution were investigated. The Fc-HTPBs were characterized by IR, ultraviolet–visible, 1H-NMR, and 13C-NMR spectra. The iron content and number of hydroxyl groups were estimated, and the properties, including thermal degradation, viscosity, and propellant burning rates (BRs), were also studied. The thermogravimetric data indicated two major weight loss stages around 395 and 500°C. These two weight losses were due to the depolymerization and decomposition of the cyclized product, respectively, with increasing temperature. The Fc-HTPB was cured with toluene diisocyanate and isophorone diisocyanate separately with butanediol–trimethylolpropane crosslinker to study their mechanical properties. Better mechanical properties were obtained for the gumstock of Fc-HTPB polyurethanes with higher NCO/OH ratios. The BRs of the ammonium perchlorate (AP)-based propellant compositions having these Fc-HTPBs (without dilution) as a binder were much higher (8.66 mm/s) than those achieved with the HTPB/AP propellant (5.4 mm/s). © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011