Heterogeneous pyrolants

It is shown that 3 -increases with increasing and that the maximum I is obtained at xi(0-80). Since a Ti-C pyrolant is a heterogeneous mixture, the reaction rate is highly dependent on xi. as well as on the particle sizes of both Ti and C. 

HMX and RDX are energetic materials that produce high-temperature combustion products at about 3000 K. If one assumes that the combustion products at high temperature are HjO, Nj, and CO, rather than COj, both nitramines are considered to be stoichiometricaUy balanced materials and no excess oxidizer or fuel fragments are formed. When HMX or RDX particles are mixed with a polymeric hydrocarbon, a nitramine pyrolant is formed. Each nitramine particle is surrounded by the polymer and hence the physical structure is heterogeneous, similar to that of an AP composite pyrolant... 

Typical acid-catalyzed reactions like the dehydration of alcohols and double bond shifts in olefins have been mentioned occasionally as reactions catalyzed by organic heterogeneous catalysts. An extensive kinetic study of the dehydration of tertiary butyl alcohol over pyrolized polyacrylonitrile has been describ-... 

Stanke et al. [166] first synthesized these copolymers because of the heterogeneous nature of composites, in terms of conductivity and transmittance. After successfully attaching a pyrrole moiety (7%) onto a copolymer of methyl methacrylate and 2-bromoethyl methacrylate, they polymerized pyrrole onto the copolymer by chemical oxidation in nitromethane and under argon. FT-IR spectra of the products show that the C—H bending vibration in A-monosubstituted pyroles at 725 cm" disappears even at the lowest pyrrole/2-A-pyrrolylethyl methacrylate (PEMA) ratio, indicating almost complete reaction. The conductivity of the 10 1 (pyrrole/PEMA) copolymer is 2 x 10" S cm" . 

Polymer powder is injected into a heat source (flame or plasma) and transported to a preheated substrate. The thickness of the coating is governed by the niunber of repeated passes of the spray gim across the substrate. A large particle size or molecular weight distribution may facilitate the formation of numerous heterogeneities within the microstructure of the coated siuface such as creating voids, trapped gasses, immelted particles, splats and pyrolized material. 

---