US EPA

1631107 

Journal Article 

CORRELATION OF BINDER MECHANICAL-PROPERTIES WITH FUNCTIONALITY TYPE AND MOLECULAR-WEIGHT DISTRIBUTION FOR HYDROXY-TERMINATED POLYBUTADIENES - C-13-NMR AND SEC STUDIES 

Ramarao, M; Scariah, KJ; Ravindran, PV; Chandrasekharan, G; Alwan, S; Sastri, KS 

1993 

Yes 

Journal of Applied Polymer Science
ISSN: 0021-8995
EISSN: 1097-4628 

49 

3 

435-444 

WOS:A1993LH11600008 

Hydroxy-terminated polybutadiene (HTPB) liquid prepolymers
(I-IX), with closely similar OH values, M(n)BAR, viscosity, and microstructure, were synthesized
by H2O2-initiated free-radical polymerization of butadiene in an isopropanol-water solvent
system. However, binders obtained by curing HTPB polymers showed wide variations in their sol
content, cross-link density, and mechanical properties. These variations were attributed to the
differences in functionality-type distribution (FTD) and molecular weight distribution (MWD) of
the polymers. FTD was interpreted in terms of H [ HOCH2 - CH = CH - CH2 approximately
approximately approximately) , V (HOCH2 - CH (CH = CH2)approximately approximately approximately
approximately], and [GRAPHICS] primary hydroxyls. [ V/G ] showed excellent linear correlation
with the elongation at break (E) of the binders. The polymers exhibited bimodal MWD and this
behavior was discussed in relation to two different initiation processes occurring. The high
molecular weight fraction (F(h)) of the various polymers was determined by reverse-phase HPLC and
showed good correlation with E. The sol content and cross-link density of the binders also showed
good correlation with the parameter V/GF(h). The parameters [ V/G ] and F(h) provide acceptance
criteria for blending different batches of polymers for propellant formulations.