Optimization and characterization of reinforced biodegradable cellulose-based aerogels via polylactic acid/polyhydroxybutyrate coating.

Vine shoots (VS) and waste eucalyptus paperboard (EP) have been used as cellulose sources (in the form of cellulose nanocrystals -CNCs- and cellulosic fibers respectively) for developing cellulose-based aerogels. Two different parameters including cellulose concentration (0.5 % and 2 % w/v) and freezing temperatures (-20 °C and -80 °C) were tested to evaluate differences in the porosity of the aerogels via Brunauer-Emmett-Teller (BET) and thermal conductivity analyses. In addition, a supplementary coating was applied to the raw aerogels by means of dipping the materials in either polylactic acid (PLA) or polyhydroxybutyrate (PHB) solutions (1 % w/v). Their microstructure was observed via SEM and the reinforcing capacity provided by the coating was measured by means of mechanical compressive tests (~10-fold improvement) and water resistance (contact angle >100°). Finally, aerogels' biodegradability was also confirmed according to the standard ISO 20200 thus providing a sustainable and high-performance alternative to conventional materials also following circular economy principles.