Showing papers by "K. N. Ninan published in 1995"

Developmental Studies on Metallised UDMH and Kerosene Gels

Abstract: The influence of particulate and hydrocolloid gellants and different surfactants on gellation of metallised stable gels of unsymmetrical dimethyl hydrazine (UDMH) and kerosene containing 30 per cent 15 micron Aluminium was studied. Metallised UDMH and kerosene gels were characterised with respect to pseudoplasticity, thixotropy, consistency and yield stress using Contrave's rheometer. The effect of shear rate and temperature on the viscosity of these gels was determined. Thermal stability, hypergolicity tests and flow rate studies were also conducted. Metallised UDMH and kerosene gels are found to be stable, thixotropic and pseudoplastic and easily flowing like a liquid under shear force.

Studies on functionality distribution of extractable sol from HTPB–isocyanate gumstock

Abstract: Hydroxyl-terminated polybutadiene (HTPB), even when cured with stoichiometric quantities of toluene diisocyanate (TDI), gives some extractable sol from the gumstock and the sol is believed to be predominantly due to the nonfunctional molecules in the HTPB. However, the present work shows that the molecules in the sol contain hydroxyl functional groups whose nature was established by hydrolyzing the urethane present in the sol and by analyzing the functionality distribution of the molecules so generated from the sol. The sol contains chain-extending difunctional and crosslinking tri- and polyfunctional molecules; however, the concentration of the former is more, when compared to the original HTPB. All three types of primary hydroxyl groups of HTPB (G, H, and V) are also present in the sol. While there is a reduction in the G-type hydroxyl in the sol, there is no major difference in the cis, trans, and vinyl contents of the backbone of the sol and HTPB. The molecules in the sol have been excluded from the crosslinked network, not only because of the lack of their functionality alone, but also as a result of network imperfections which are an integral part of nonlinear polymerization reactions. © 1995 John Wiley & Sons, Inc.

Viscoelastic Behaviour of Solid Propellants based on Various Polymeric Binders

Abstract: The dynamic mechanical properties of different binders and corresponding propellants are studied in terms of storage modulus and loss tangent. The binders investigated are HTPB, CTPB, PBAN, HEF-20 and ISRO polyol. The viscoelastic behaviour is investigated using Rheovibron viscoelastometer at 35 Hz covering a wide temperature range (-100 degree centigrade to 100 degree centigrade). The properties of the binder and corresponding propellant are compared in terms of parameters, tan delta/sub max/, T/sub g/ and the trend of their master relaxation modulus curves. It is found that polybutadiene binders exhibit lowest T/sub g/ (around -60 degree centigrade) and ISRO polyol the highest (near -20 degree centigrade). The propellants have higher moduli than the binders at any temperature. The master relaxation modulus curve is influenced by the type of propellant.

Size exclusion and adsorption column chromatographic studies on functionality distribution of HTPB

Abstract: Adsorption column chromatography and size exclusion chromatography have been used to determine the functionality distribution of hydroxyl terminated polybutadiene (HTPB), a modern solid propellant binder. The resin after conversion to 3,5-dinitrobenzoyl ester was separated into various fractions on a silica column. The fractions were analysed using a dual detector (UV and differential refractive index) analytical gel permeation chromatograph. The functionality of each fraction calculated from the chromatogram showed a continuous increase with increase in the molecular weight. The adsorption chromatography method is unable to fractionate the polymer into fractions with specific functionality. All the fractions have molecules ranging from monofunctional to multifunctional ones and therefore the apportionment method followed in the conventional adsorption chromatography method yields conflicting results.