Accession Number : ADA306600

Title :   Determination of Kinetic Parameters of Six Ablation Polymers by Thermogravimetric Analysis.

Descriptive Note : Technical note,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CEN TER

Personal Author(s) : Nelson, James B.

PDF Url : ADA306600

Report Date : APR 1967

Pagination or Media Count : 43

Abstract : Six polymers used in ablation heat shield composites were investigated by thermogravimetric analysis (TGA) at temperature-rise rates of 3 K per minute to 18 K per minute in vacuum. These materials were nylon, silicone, polyformaldehyde, and three phenolics. Empirical kinetic parameters were determined for these materials by five different methods (all based on an Arrhenius relation): a direct-solution method, an integral method, a maximum -decomposition method, a multiple-heating -rate method, and a difference method. A best set of parameters was determined for each material by comparing experimental TGA curves with TGA curves derived from the parameters found by each method. The kinetic parameters for the individual materials were shown to satisfactorily describe the mass loss of two composite materials of current interest, a low-density phenolic-nylon and a low-density phenolic-silicone. Direct solution was found to be the most satisfactory method.

Descriptors :   *POLYMERS, *COMPOSITE MATERIALS, *NYLON, *HEAT SHIELDS, *PHENOLIC PLASTICS, *THERMOGRAVIMETRIC ANALYSIS, *SILICONE PLASTICS, REENTRY VEHICLES, ABLATION, HYPERSONIC FLIGHT, DECOMPOSITION, THERMAL DEGRADATION, FORMALDEHYDE, HEAT RESISTANT MATERIALS, ABLATIVE MATERIALS, ARRHENIUS EQUATION.

Subject Categories : Laminates and Composite Materials
      Plastics

Distribution Statement : APPROVED FOR PUBLIC RELEASE