Accession Number : AD0486589

Title :   THE LINEAR PYROLYSIS OF POLYMETHYLMETHACRYLATE.

Descriptive Note : Master's thesis,

Corporate Author : STEVENS INST OF TECH HOBOKEN NJ DEPT OF MECHANICAL ENGINEERING

Personal Author(s) : McAlevy, Robert F., III ; Lee, Suh Yong ; Smith, Westcott H.

Report Date : JUL 1966

Pagination or Media Count : 38

Abstract : Polymethylmethacrylate surface linear pyrolysis produced by intense surface heating was studied experimentally. This material is typical of thermoplastics used in composite solid propellants, hybrid rocket motors, etc., and complete theoretical descriptions of their combustion phenomena incorporate as the pivotally important boundary condition of their pyrolysis characteristics. Results of this study can have immediate practical application. Surface heating was produced by means of a nearby flame established between the emerging pyrolysis product vapors and an impinging jet of gaseous oxygen. Cylindrical test specimens (3/4 in. diameter) were aligned with the centerline of the oxygen discharge nozzle, and positioned 1-1/2 in. downstream of the exit plane. Varying oxygen discharge rates resulted in reproducible surface regression rates between 0.08 and 0.32 mm/sec. Very fine thermocouples (15-micron bead diameter) embedded in the specimens yielded subsurface temperature distributions. Interpretation of these data indicated: existence of a liquid-like region between the solid-like region and vapor phase; thermal diffusivity values that were consistent with established values; existence of exothermic and endothermic subsurface processes. Values of surface temperatures (at approximately 500 C) obtained by means of an optical technique were preproducible with + or - 4K. These data were consistent with liquid-vapor interface data obtained by the thermocouple technique. This approach is superior to those previously employed for obtaining thermoplastic surface pyrolysis data. However, the process is sufficiently complex in the case of polymethylmethacrylate to preclude detailed interpretation. (Author)

Descriptors :   *PYROLYSIS), (*ACRYLIC RESINS, SURFACE TEMPERATURE, THERMOPLASTIC RESINS, THERMOCOUPLES, PHASE STUDIES, THERMAL DIFFUSION, EMISSIVITY, INFRARED RADIATION, MEASUREMENT.

Subject Categories : Physical Chemistry
      Plastics

Distribution Statement : APPROVED FOR PUBLIC RELEASE