Kinetic, rheological, thermochemical and mechanical properties of polymer matrices

Rocket motors with solid propellants contain, among other ingredients, a polymer matrix. This matrix works as a binder for the rest of the propellant. In this work, 26 polymer matrices were produced. They were characterized both mechanically and thermally. In addition, I studied the flow properties and reaction kinetics during curing.
Most of the polymer matrices were mixed with the hydroxyl-terminated prepolymer HTPB. Some of the samples were made from Terathane 2000, which is a hydroxyl-terminated polyether. Several parameters that might have an impact on the curing process and quality were varied. This included curing agent, curing catalyst, burn rate catalyst and amount of plasticizer.
The results showed that there was a difference between the curing agents in how fast they reacted with the prepolymer. Furthermore, the reaction rate was significantly increased with the addition of a curing catalyst. In this way, we have tools to be able to control the curing. Two of the burn rate catalysts also catalyzed the curing. This should be taken into account when choosing a burn rate catalyst.
Most of the reactions appeared to follow second order (or pseudo second order) kinetics. This also applied to catalyzed curing, which follows a more complicated mechanism than the uncatalyzed reaction.
The hardness of cured HTPB samples was somewhat dependent on the compositions. The plasticizer dioctylsebacate had the greatest effect, which made the samples significantly softer. The glass transition temperature was also more dependent on the plasticizer than any other parameter.