Poly(Lactic Acid)-Based Nanobiocomposites with Modulated Degradation Rates

Abstract

In the field of biodegradable polymers such as poly(Lactic Acid) (PLA), it is quite well known that their kinetics of hydrolysis strongly depend on the pH of the hydrolyzing medium. The idea explored during this study focused on PLA, is the addition of additives that are able to control the pH of water when it diffuses inside the polymer. For instance, acids (i.e. succinic acid, also used as food additive) are bio- and eco- friendly additives that are able to play this role. In order to control the release of these molecules and their dispersion inside the polymer, their intercalation in biocompatible nanofillers like layered double hydroxides (LDH) is here considered. The additives have been dispersed in the polymer by melt compounding, commonly used in the plastic industry. Several composites of PLA (4032D) and LDH intercalated with organic acids (succinic, fumaric, and ascorbic acid) have been obtained by an extrusion process. From all extruded materials, PLA films obtained by compression molding were then subjected to hydrolysis tests. The results showed that the mentioned molecules, dispersed in the polymer, are able to control the rate of hydrolysis, and experimental results show an increase of degradation time for samples containing LDH-organic acid (in particular with LDH-succinic acid), making such hybrid additives an appropriate and efficient solution for PLA.

A review on degradation mechanisms of polylactic acid: Hydrolytic, photodegradative, microbial, and enzymatic degradation

“…During the hydrolytic degradation of PLA, chain cleavage reactions are favored within amorphous regions, and subsequently, increases in polymer crystallinity are observed. [127,128] Four basic parameters control the hydrolytic degradation of a PLA particle in aqueous solution: quantity of absorbed water, diffusion rate and coefficient of chain fragments within the polymer, and solubility of degradation products. Indeed, two degradation mechanisms which are heterogeneous or surface reactions and bulk or homogeneous erosion, can be predicted.…”

Potential Natural Fiber Polymeric Nanobiocomposites: A Review

“…Recently, nanofillers have been considered to be highly potential components for enhancing the polymeric properties and mechanical performances of NBCs. Currently, cheaper, lighter, stronger, and thinner composites are a target of researchers and manufacturers, who hope to achieve such nanofillers in superior material selection [126,127]. When the size of a larger surface polymeric matrix is shrunken to a smaller area in the nm (nanomaterial) range, various flexible functionalities appear, along with an excellent mechanical strength (tensile strength and stiffness), compared to the raw form or without nano-treated composites [128].…”

Biodegradable Polylactide–Poly(3-Hydroxybutyrate) Compositions Obtained via Blending under Shear Deformations and Electrospinning: Characterization and Environmental Application

“…PLA is one of the most promising biopolymers obtaining on polymerization of D-, L-lactic acids originated through enzyme fermentation of renewable natural products such as corn, potato, sugar beet, etc. By a range of physical characteristics commercial-grade PLA resembles the biostable synthetic polymers polystyrene and poly(ethylene terephthalate) [7], but its biodegradability can occur only in hydrolytic and enzymatic media [8][9][10]. Being a good thermoplastic, it can be extruded into films and pellets, molded into goods of diverse shape and via electrospinning formed into ultrafine fibers [11,12].…”