Poly(L‐lactic acid) with added α‐tocopherol and resveratrol: optical, physical, thermal and mechanical properties

Abstract

Poly(L-lactic acid) (PLLA) films containing various concentrations of two natural antioxidants, α-tocopherol and resveratrol, were fabricated by a melt compounding and compression molding process. The influence of the antioxidants on the optical properties such as color and UV-visible light transmission was analyzed. The thermal, mechanical, rheological and physical properties of PLLA films with added antioxidants were assessed. PLLA films with added α-tocopherol and resveratrol showed a yellowish brown color and the lightness was influenced by the presence of the antioxidants. The glass transition and melting temperatures were significantly reduced with the addition of antioxidants while enhanced thermal stability was observed, which could be a benefit and important for processing and production. PLLA films with added antioxidants were slightly more hydrophobic than neat PLLA. The combination effect of plasticizing and enhancement of the elastic modulus with differing concentrations of two antioxidants played a critical role in the mechanical and thermomechanical properties of PLLA films. The melt viscosity of the PLLA films with added antioxidants was substantially higher than that of neat PLLA. The higher melt viscosity and G (ω) could be an indication of formation of entanglement between PLLA and the two antioxidants.

Potential of Lignins as Antioxidant Additive in Active Biodegradable Packaging Materials

“…The packaging matrix chosen was poly(lactide) (PLA) because of its renewable character. The inclusion of natural antioxidants in PLA in the aim of developing an active material has already been suggested in literature [43][44][45]. Furthermore, some studies already exist pointing to the feasibility of inclusion of lignin into PLA [5,9,46,47].…”

Characterization of PLA-limonene blends for food packaging applications

“…Furthermore, PLA modified with natural origin compounds has been proposed as active packaging [8,23,24]. In this way, Hwang et al, (2011) proposed PLA with added α-tocopherol and resveratrol as promising active functional membranes [8]. Jamshidian et al, (2012) studied PLA with ascorbyl palmitate although they reported high loss of antioxidant during polymer preparation and negatives results on PLA transparency [24].…”

“…So, additives are require for transparent PLA films to block light transmission [22]. Furthermore, PLA modified with natural origin compounds has been proposed as active packaging [8,23,24]. In this way, Hwang et al, (2011) proposed PLA with added α-tocopherol and resveratrol as promising active functional membranes [8].…”

“…In this sense, poly(lactic acid) (PLA) is one of the most attractive biopolymers with many short-term or disposable applications, such as disposable cutlery (plates, cups, lids and drinking straws), bags and film packaging [4,5]. PLA is also widely used in rigid and flexible food packaging applications [6] since it has been approved by the US Food and Drug Administration (FDA) as a food contact substance [7,8].. However, the use of PLA for food packaging is somewhat limited because of its poor ductility, thermal and oxygen barrier properties [3].…”

Industrial vegetable oil by-products increase the ductility of polylactide

“…The blending with the unsaponifiable compound !-tocopherol showed small gains in elongation at break, which extends already existing knowledge. It was already shown that the use of !-tocopherol as a natural antioxidant in PLA at small quantities (<4 wt%) induced a slightly T g decrease [74] but no increase in elongation at break [75]. Here, no elongation at break improvement upon was found using greater !-tocopherol amounts, despite solubility was assessed to be higher than other molecules (such as HPO and HCO, Table 4) and a T g decrease was observed (Table 3).…”