Liquefied agricultural residues for film elaboration

Agricultural residues (corn stover, corncob, vine shoots and blueberry tree pruning) with low added value were converted through liquefaction into liquefied products. Their capability to form films was evaluated. Results indicated that liquefied products production under liquefaction conditions is completely feasible with yields in the case of corn residues above 90%. The IOH and viscosities were in the range of 309-441 mg of KOH/g and 0.16-0.19 Pa · s, respectively. These values make the liquefied agricultural residues an interesting alternative to be considered as constituent in liquefied-based materials and composites elaboration. On the other hand, homogeneous, opaque and dark brown flexible films, using weight ratio of (liquefied agricultural residue/starch)/glycerol of (90/10)/30, were produced. The films obtained with corn residues as starting material showed adequate behavior considering physical and mechanical features. DMA measurements for liquefied corncob-films showed higher values of thermal and dynamic mechanical parameters (Tg: 112 °C; E′: 42 MPa until 110 °C) compared to control film (starch/glycerol: 70/30), which showed a material with higher thermal stability. The results demonstrated the suitability in the conversion of different renewable and abundant resources into liquid form and their physico-chemical properties for first step film production, which might have interesting perspectives in polymer processing area for bioplastics development in agricultural applications.