Open Cell Polyurethane Foams for New Filters with Supported Adsorbents

Abstract

A flexible foam was developed based on polymeric diphenylmethane diisocyanate (MDI) to be used as support for pre-synthesized adsorbent additives (activated carbon) for air-conditioning filters that provide air purification and improve indoor air quality. Foam for air purification filters must be an open cell foam with low density, air permeability and the adsorbents must retain indoor air pollutants, such as volatile organic compounds (VOCs). To achieve the right structural characteristics different polyether polyols, catalysts and surfactants were used and several tests of pressure drop, apparent volume, real volume and densities were performed. Another aspect that was studied in this work was the adsorption capacity of several activated carbons and the foam matrix influence in the adsorption. For that purpose room temperature adsorption isotherms of toluene, which is a probe of noxious aromatic VOCs, were determined and compared. For scale up purpose, rise time curves of the foams were measured. This study was made at different starting temperatures and with different types and quantities of catalyst. The relationships rise time/starting temperature and rise time/quantity of catalyst were obtained and expressed in equations.