Browsing by Author "Sabando, Constanza"

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    Biocomoposites of polylactic acid/poly(butylene adipate-co-terephthalate) blends loaded with quinoa husk agro-waste: thermal and mechanical properties
    (2022) Ponce, Giovanni; Rodriguez-Llamazares, Saddys; Rivera, Patricia Castano; Castano, Johanna; Oporto-Velasquez, Gloria; Sabando, Constanza; Ide, Walter; Nesic, Aleksandra; Cabrera-Barjas, Gustavo
    Quinoa husk (QH) is often discarded without being utilized. This study investigates an alternative route for this agro-waste resource as a raw material in the preparation of bioplastic composites. The effect of QH on the mechanical and thermal properties of thermoplastic poly(lactic acid)/poly(butylene adipate-co-terephthalate) (PLA/PBAT) blends was evaluated. The composites were prepared by melting compounding. The content of quinoa husk in composite materials varied from 0-30 wt%. The results demonstrated that addition of quinoa husk in PLA/PBAT blend induced slight increase in crystalline phase of PLA, which was evidenced by FTIR and DSC analysis. However, it reduced the mechanical and thermal properties of materials. The 30 wt% load of quinoa husk in formulation led to decreased tensile strength (by 45.5%), elongation at break (by 85.8%), thermal stability (by 23.5%) and flexural strength (by 36%) of final biocomposite material, when compared to the control biopolymer blend. Although addition of quinoa husk in bioplastic material did not improve mechanical properties, load of 20 wt% QH in PLA/PBAT still provided satisfied tensile strength of 19 MPa and flexural strength of 27 MPa, showing that quinoa husk can add value to lignocellulosic by-product/agro waste, particularly decreasing the cost and increasing the sustainability of bioplastic materials for use in the agriculture industry.
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    Sodium alginate-g-polyacrylamide hydrogel for water retention and plant growth promotion in water-deficient soils
    (2024) Pettinelli, Natalia; Sabando, Constanza; Rodriguez-Llamazares, Saddys; Bouza, Rebeca; Castano, Johanna; Valverde, Juan Carlos; Rubilar, Rafael; Frizzo, Marcela; Recio-Sanchez, Gonzalo
    Natural polymer-based hydrogels are preferred as soil water retention agents due to their inherent biocompatibility and biodegradability. Generally, these natural polymers are chemically modified by graft polymerization of vinyl monomers to improve their water absorption and retention properties. Among the polysaccharides used to prepare natural hydrogels, those based on sodium alginate (Alg) stand out for their high-water absorption and retention capacity, as well as for their ability to promote plant growth. The main objective of this study was to develop a biodegradable alginate-based hydrogel as a water retainer to promote plant growth under water deficit conditions. The synthesis was achieved by grafting poly(acrylamide) (PAM) onto Alg backbone, using bisacrylamide as chemical crosslinker and different ratios of alginate:acrylamide (Ac). In addition, Eucalyptus nitens seedlings were used as a model plant to evaluate the effect of alginate-g-polyacrylamide (Alg:PAM) hydrogel application to the growing medium on plant survival, growth, and physiological responses under both wellwatered and water-deficient soil conditions. The maximum degree of swelling (65 g/g) was obtained for the hydrogel prepared. The pseudo-second order model described the water uptake kinetics of the hydrogel. The degradability of Alg:PAM hydrogel reached up to 85 % in 5 weeks in soil and occurs by breaking the glycosidic bonds of the alginate. The E. nitens seedlings cultivated with different doses of Alg:PAM hydrogel (4:1 Alg:Ac) showed higher values of height and root diameter relative growth, survival and photosynthetic responses in comparison to non-treated plants. The results indicate that Alg:PAM hydrogel (4:1 Alg:Ac) has promising applications in forestry as a water retention and seedling growth promoter under water deficient conditions.