Addition of α‐tocopherol on poly(lactic acid): Thermal, mechanical, and sorption properties

Abstract

This work investigates the effect of the addition of a well-known antioxidant, a-tocopherol in poly (lactic acid) flexural and barrier properties. For that purpose, films of poly(lactic acid) enriched with 0, 2.2, and 4.4% of a-tocopherol were prepared. Differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis were used to characterize the changes in the mechanical and thermal properties. The sorption of oxygen and carbon dioxide in the prepared enriched films of poly(lactic acid) was measured at different temperatures between 283 and 313 K and pressures up to atmospheric pressure using a Quartz Crystal Microbalance. Although no significant changes were found in the mechanical and thermal properties, the addition of a-tocopherol promotes an increasing in the oxygen sorption and the convex shape of the isotherms indicate a strong interaction gas-polymer. Regarding the sorption of carbon dioxide, no pronounced effect was found.

Preparation, characterization, and oxygen scavenging capacity of biodegradable α‐tocopherol/PLA microparticles for active food packaging applications

“…The observed crystallinity increase was explained hypothesizing that AT behaves as a plasticizing additive that increases the mobility of PLA molecules in solid state, thus allowing more rearrangements of polymer chains. An effective plasticizing action of AT was also found by other authors on several polymer systems .…”

A traditional aboriginal condiment as an antioxidant agent in the development of biodegradable active packaging

“…Certainly, merkén particles were intermingled between the polymer chains and broke intramolecular and intermolecular interactions between the polymeric chains; this resulted in a decrease in T g . The same effect was already reported for a PLA‐based film with different added antioxidants, such as α‐tocopherol, butylated hydroxytoluene (BHT), and marigold flower extract . Nevertheless, the addition of a higher concentration of merkén caused an increase in the rigidity.…”

Demonstrating the mechanism and efficacy of water‐induced shape memory and the influence of water on the thermal properties of oriented poly(d,l‐lactide)

“…In the FTIR spectra of the PDLLA, these changes were seen in the intensities and locations of the peaks created by the IR absorptions of the OH bonds of the water molecules absorbed into the polymer matrix, 22,23 the OH bonds of the polymer, 24 and the C@O bonds of the polymer. 24,25 When the water molecules diffused between the polymer chains, they both separated the chains and interacted with them. As a result, the slightly stronger interaction (dipole-dipole and/or hydrogen bonding) between the polar OH groups and other polar groups of the original polymer was disrupted.…”

“…24,25 The increase in the intensities and the shifting of the bands were the most significant during the first day of immersion, after which the positions of the bands moved only slightly or remained unaltered. These observations corresponded to the results of the mass change measurements and differential thermal analysis, as presented previously.…”

“…The main changes in the FTIR spectra of the PDLLA films, which were immersed in water after vacuum drying, were seen in the intensities and locations of the peaks created by the IR absorptions of the OH bonds of the water molecules absorbed into the polymer matrix (3651-3657 and 1625-1630 cm 21 ), 22,23 the OH bonds of the polymer (3547-3569 cm 21 ), 24 and the C@O bonds of the polymer (1748-1765 cm 21 and the overtone at 3504-3509 cm 21 ). 24,25 The increase in the intensities and the shifting of the bands were the most significant during the first day of immersion, after which the positions of the bands moved only slightly or remained unaltered.…”