Volatile out gassing characteristics of highly filled ethylene vinyl acetate binder materials: Gas phase infra-red spectroscopy

Abstract

Gas phase Infra-red (IR) spectroscopy has been used to investigate volatile out gassing properties of highly filled poly (ethylene-co-vinyl acetate) materials. A Scout-EN™ heated gas cell was interfaced to a vacuum FTIR spectrometer, and the quantification of evolved species was achieved through calibration of the gas cell with certified gas standards. The volatile out gassing properties were monitored as a function of time under vacuum conditions (<1 mbar). Acetic acid, carbon dioxide and water were identified as the major out gassing products through IR absorption peaks at 1797, 2354 and 3853 cm−1, respectively. A comparison of three highly filled poly (ethylene-co-vinyl acetate) resins is reported. In each case, low molecular weight silicone impurities linked to processing operations were identified in the headspace. Successive out gassing runs (pump downs) showed a diminishing equilibrium release level, suggesting a reduction in initial concentration of volatiles within the material. Two different initial phases of species may exist in highly filled materials; ‘weakly-bound’ and relatively ‘tightly bound’ phases of volatile species. The gas phase IR test methodology reported here is a useful analytical tool for investigating out gassing characteristics at the individual and multi-material levels, providing parameter estimates and material sensitivity data for system level ageing models in support of core programmes in materials qualification and life assessment.