Poly(lactic acid)–thermoplastic starch–cotton composites: Starch‐compatibilizing effects and composite biodegradability

Abstract

Poly(lactic acid) (PLA) is a biodegradable, brittle, and high-cost polymer, which can be applied over structural components and green packaging. In this study, we reinforced PLA with natural cotton (10 wt %) and thermoplastic starch (TPS; 3 wt %) to obtain a biodegradable and lower cost composite. TPS was incorporated in three distinct ways: it was blended, coated, and blended and coated. In this study, we investigated the compatibilization of TPS in the improvement of matrix-reinforcement adhesion and increase in the tensile behavior without a compromise in biodegradation. The samples were investigated with thermal analysis, dynamic mechanical thermal analysis, tensile testing, scanning electron microscopy, confocal laser scanning microscopy, and hydrolytic degradation. The results show that the coupling effect was more pronounced in the PLA TPS -cotton TPS (hybrid system with PLA and cotton) hybrid system. This formulation presented a higher glass-transition temperature, thermal stability, storage modulus, wettability, and ductility. The TPS addition improved the adhesion between the matrix and starched cotton fiber and retarded abiotic biodegradation. These properties will allow for green applications.

The effect of periodate oxidation, tert-butanol treatment, and starch addition in improving melt dispersion of cellulosic fillers in PBAT

“…The positive effect of starch on the properties of other composites of polymer with cellulose has also been reported but it is seldomly explicitly mentioned as a compatibilizing effect except in PLA. 32,33 Several studies have demonstrated that using tert-butanol (TB) as a freeze-drying medium during the production of cellulose nano-fibers or nano-crystals prevents their aggregation [34][35][36][37][38] but seldomly to produce composites. Petersson et al 39 studied composites based on PLA and cellulose nanocrystals prepared by solution casting.…”

Development of Toughened Flax Fiber Reinforced Composites. Modification of Poly(lactic acid)/Poly(butylene adipate-co-terephthalate) Blends by Reactive Extrusion Process

“…So far, the PLA/PBAT blend systems have been tested as materials intended for the production of films, injection molding or three-dimensional (3D) printing. The production of composite laminates based on PLA resin has not been the subject of intensive research, so far, but the appearance of this type of materials on the market indicates an interesting trend in the use of biopolymers The use of PLA as a matrix for composites and laminates was already investigated in case of ramie fibers [ 60 , 61 ], bamboo [ 62 , 63 ], cotton [ 64 , 65 , 66 ], kenaf [ 67 ] or flax [ 26 , 68 , 69 , 70 ]. The use of flax fiber (FF) reinforcement was for us the most promising concept, since the reinforcing efficiency for already investigated PLA/FF composite systems was very high, which was confirmed in many studies [ 68 , 71 , 72 , 73 , 74 ].…”

Biodegradation of poly(lactic acid)—cassava bagasse composites produced by injection molding

“…Reviews on PLA (Macedo et al; 6 Farah et al; 7 Castro‐Aguirre et al 8 ) included processing techniques and applications, degradation pathways, end‐of‐life scenarios for PLA products, and its environmental footprint. According to these reviews, the PLA's biodegradation depends on several parameters and can take weeks to months.…”

“…PLA's disadvantage is its high cost compared to conventional polymers, but blends with low‐cost biodegradable materials become PLA‐based composites economically viable and improve biodegradability 1,6 . The application of lignocellulosic fibers as reinforcement has been widely studied because they have low density and low abrasiveness and can be incorporated in high levels reducing cost since most of them are agro‐industrial residues from sugarcane, cassava, wood, and coir 9–13 …”

“…Macedo et al 6 produced composites of PLA/corn starch/cotton fibers, and they observed higher mechanical resistance, higher ductility, and adhesion with the cotton fibers. Tawakkal et al 15 produced PLA/kenaf composites and observed that the composites' density increased with kenaf content, limiting its applications, and the flexural properties of the composites were improved compared to neat PLA.…”