Cellulose/biochar aerogels with excellent mechanical and thermal insulation properties

Aiming at investigating the use of alternative materials for the production of thermal insulation and, mainly, to replace the carbon structures (graphene and nanotubes), extensively used in the development of aerogels, the present study had the objective to produce cellulose/biochar aerogels and to evaluate their properties. The aerogels were produced from Pinus elliottii cellulose fibers and biochar produced from these fibers. The materials were characterized in their physical, thermal and mechanical properties. They were extremely light and porous, with a density between 0.01 and 0.027 g cm(-3) and porosity between 93 and 97%. Several percentages of biochars were added to the cellulose suspension (0-100% w/w). The use of 40 wt% biochar provided a 60% increase in the compressive strength of the aerogel in relation to the cellulose aerogel. Besides that, the addition of this carbonaceous structure did not influence significantly the thermal conductivity of the aerogels, which presented a thermal conductivity of 0.021-0.026 W m(-1) K-1. The materials produced in the present research present a great potential to be used as insulators due to the low thermal conductivity found, which was very similar to the thermal conductivity of the air and also of commercial materials such as polyurethane foam and expanded polystyrene.