Influence of fillers and bonding agents on the viscoelasticity of highly filled elastomers

Abstract

International audienceABSTRACT: Highly filled elastomers such as solid propellants exhibit a complex nonlinear viscoelastic behavior. This work aimed atdetermining the influence of binder–filler and filler–filler interactions on the microstructure and the viscoelastic properties of the propellantusing a design of experiments method. The influences of the filler fraction and of the filler–binder bonding agents (FBBA)were measured by swelling experiments and prestrained dynamic mechanical analyses. The results showed that FBBA react on the fillersurface and concentrate the curing agents in the vicinity of the fillers. The nonlinearity of the viscoelastic behavior originatedfrom filler–filler interactions that created high stress zones between fillers and therefore constrained the movements of the macromoleculesof the binder. Filler–binder interactions induced by the FBBA increased the filler effective volume as well as the heterogeneousstress distribution in the microstructure. VC 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40664

Microstructure and deformation mechanisms of a solid propellant using 1 H NMR spectroscopy

“…The exact synthesis of the FBBA molecules is confidential and will therefore not be described. More details on the FBBA are provided in [6] but are not essential to this study. The binder is constituted of HTPB prepolymer cured with a methylene diicyclohexyl isocyanate (MDCI).…”

“…The propellants numbered 0 to 21 (Table 1) correspond to a design of experiment (DoE) allowing us to determine the influence of four composition factors (the filler fraction, the FBBA, the NCO/OH ratio, and the plasticizer content) on the properties of an HTPB-based solid propellant. The principles of building the DoE have been detailed elsewhere [1,6].…”

“…Finally, as presented in details in [1,6], the DoE method is applied to the 12 responses: T 2s ; T 2m ; T 2l ; f s ; f m ; f l , and their derivatives with respect to the effective strain k à ; @T 2s;k à ; @T 2m;k à ; @T 2l;k à ; @f s;k à ; @f m;k à , and @f l;k à , using the Design-Expert Ò software. A model with n coefficients can only be investigated with a DoE consisting of at least n runs.…”

“…The relations between the nonlinear mechanical behavior at the macroscopic scale and the microstructure at the scale of the fillers or the polymer chains have been explored [1][2][3][4][5][6]. However, direct experimental evidence of the physical mechanisms of deformation at the scale of the polymer network is difficult to obtain.…”

Effect of tris (2,3-epoxypropyl) isocyanurate on dynamic modulus of CTBN-based composite rocket propellant

“…Increase of the G'' values indicates the increase of dissipation energy within microstructure of the tested composite propellant compositions. This can be explained by the influence of TEIC on creating the reinforcing layer around the filler particles [15]. Thus, the resulting polymer layer increases the effective volume of the filler particles and links the polymer network to the surface of the fillers.…”