Recycling paper production waste sludge in polyurethane foam to improve fire resistance and reduce environmental impact

Abstract

The wide range of raw materials as well as the variety of building blocks has led to almost unlimited formulation possibilities for polyurethane materials. Although, one of the main problems associated to large scale production of such materials is a great dependance on petrochemical resources. Whereas the environmental impact has a strong influence on the development of polymeric materials, it is of great importance to develop bio- or/and waste-based materials in order to fullfill the requirements of sustainability and improve performance characteristics of the final products. The research presents fully water blown rigid polyurethane foams obtained using forestry waste-based polyol from tall oil. The obtained products have been additionally modified with paper production waste sludge (PPWS) in order to improve not only the physical-mechanical performance but fire resistance as well. Equally, the research presents the environmental impact of four raw material systems. It has been shown that PPWS particles act as nucleation promoters thus reducing the thermal conductivity values by 15.3% and 11.3% and increasing compressive strength from 224 kPa to 275 kPa at the amounts of, respectively, 10 wt.% and 20 wt.%. Ignitability test results show that the PPWS particles are recycled in polyurethane foams, the slower ignitability is observed thus assuming that the particles act as a flame barrier due to decomposition of existing CaCO3 to CaO and CO2. Additionally, cone calorimetric measurements show that the addition of PPWS particles into polyurethane system leads to the reduction in release of toxic gases such as CO2 and CO during fire. The system of tall oil polyol, waste and PPWS particles reduces carbon dioxide emission during production by 60.8% and 39.6% compared to conventional polyurethane foam materials at, respectively, 10 wt.% and 20 wt.% of PPWS particles.