Polymer surface reflectance‐absorptance characteristics

During an investigation of the time for ignition of polymeric materials under the influence of radiant heating, it was found that the polymer surface reflectance‐absorptance characteristics were a major factor in the variance of the ignition times. A subsequent research study was made of the reflectance‐absorptance characteristics of those polymers used in the ignition testing. Reflectance values were obtained over the wavelength of 0.3 to 2.5 microns using a double‐beam Cary model 14 spectrophotometer with an integrating sphere reflectometer and over the wavelengths of 1.0 to 10.0 microns using a Gier‐Dunkle Hohlraum with a Perkin‐Elmer spectrophotometer. Absorptance values were obtained by means of Kirchoff's Law, Drawings and graphs are included which illustrate the test apparatus and type of data collected. A table of average absorptances of several polymers are given and listed according to the particular type of heat source used. Average absorptances of the polymers over the monochromatic wavelength span of the heat sources were calculated using the equation Mathematical analyses were developed and are presented for both the integrating sphere reflectometer and Gier‐Dunkle Hohlraum unit. Drawings and graphs are included which illustrate the test apparatus and type of data collected. A table of average absorptances of several polymers are given and listed according to the particular type of heat source used.