화학공학소재연구정보센터
Journal of Applied Polymer Science, Vol.103, No.3, 1529-1538, 2007
Diffusion rates and the role of diffusion in solid propellant rocket motor adhesion
Diffusion rates can give important information for the adhesion process across the bondline between insulation and propellant in solid propellant rocket motors. Diffusion coefficients of low molecular weight species such as crosslinkers and plasticizers have been measured by the weight of uptake method in polymer materials that are candidates for propellant contact. The materials were EPDM insulation sheets and "liners," based on HTPB, HTPE, or GAP, and with different degrees of particle filling. Plots of relative mass gain as a function of the square root of time showed good linearity up to 20-50% weight increase and the diffusion coefficients could thus be determined with good accuracy. The diffusion coefficients for the low molecular weight isocyanates and plasticizers in these materials vary between 10(-11) and 10(-17) m(2) s(-1), dependent on material types and particle filling. In most cases, the results can be explained by the solubility parameters of the organic liquids and polymers. For the particle filled samples, the diffusion coefficients decrease with increasing degree of particle filling, and the decrease is faster than predicted by the Maxwell-Fricke or the Keller models for arrays of smooth spheres. (c) 2006 Wiley Periodicals, Inc.