Liquefaction of corn husks and properties of biodegradable biopolyol blends
2020
Briones, Rodrigo | Rodríguez, Jesús | Labidi, Jalel | Cunningham, Eoin | Martin, Peter
BACKGROUND: A valorization route of corn husks from agrarian practices was performed by liquefaction using glycerol as liquefaction solvent to obtain biopolyols used as bioadditives in starch blends with the aim to find a useful industrial application in polymer processing. RESULTS: Low‐molecular‐weight liquefied products obtained from a practically total conversion reaction can be used for composite formulations (OH number, 310 mg KOH g⁻¹; viscosity, 3.4 Pa s; molecular weight, 549 g mol⁻¹). Concurrently, starch thermoplastic blends using various proportions of biopolyol (40, 30 and 20 wt%) as plasticizer were produced with maximum torque and plasticization energy ranging from 3.4 to 15.1 Nm and from 1.7 to 9.1 Nm min⁻¹. The starch/biopolyol (70/30) sheets obtained by thermopressing showed properties similar to those of controls (starch/glycerol: 70/30), such as sensitivity to environment, retrodegradation, biodegradability and density; however, mechanical properties exhibited better performance compared to controls (Young’s modulus, 14 MPa; strain at break, 33%; tensile strength, 1.2 MPa), which indicates a material with major mechanical balance. CONCLUSIONS: The adequacy in the conversion of corn husks into biopolyols that could be used as improved biobased plasticizers to obtain biodegradable blends is revealed. Hence, this study demonstrates that liquefied corn husk residues are sustainable resources with suitable properties for polymer processing, which can be applied in bioplastics and be considered as a value‐added feature. © 2020 Society of Chemical Industry
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