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

Abstract

Recently, thoughtful disagreements between scientists concerning environmental issues including the use of renewable materials have enhanced universal awareness of the use of biodegradable materials. Polylactic acid (PLA) is one of the most promising biodegradable materials for commercially replacing nondegradable materials such as polyethylene terephthalate and polystyrene. The main advantages of PLA production over the conventional plastic materials is PLA can be produced from renewable resources such as corn or other carbohydrate sources. Besides, PLA provides adequate energy saving by consuming CO2 during production. Thus, we aim to highlight recent research involving the investigation of properties of PLA, its applications and the four types of potential PLA degradation mechanisms. In the first part of the article, a brief discussion of the problems surrounding use of conventional plastic is provided and examples of biodegradable polymers currently used are provided. Next, properties of PLA, and (Poly[L‐lactide]), (Poly[D‐lactide]) (PDLA) and (Poly[DL‐lactide]) and application of PLA in various industries such as in packaging, transportation, agriculture and the biomedical, textile and electronic industry are described. Behaviors of PLA subjected to hydrolytic, photodegradative, microbial and enzymatic degradation mechanisms are discussed in detail in the latter portion of the article.

Functional Properties and Molecular Degradation of Schizostachyum Brachycladum Bamboo Cellulose Nanofibre in PLA-Chitosan Bionanocomposites

“…The previous review on the degradation of PLA showed that it occurs in different ways, such as hydrolysis (molecular), microbial, thermal photodegradation, and enzymatic. However, the degradation studies of PLA in the soil mainly combine enzymatic and microbial [ 11 ]. PLA has a high tendency to degrade under soil since it contains different types of bacterial.…”

“…PLA has a high tendency to degrade under soil since it contains different types of bacterial. However, as observed in these studies, the degradation of PLA took a long time because microbial action does not occur until after hydrolysis [ 11 ]. The schematic diagram of the degradation of the biocomposite is shown in Figure 3 .…”

“…Among biopolymers, PLA has higher thermal stability, making it suitable for automobile and packaging applications that require long-term use. As it is common to most biopolymers, PLA has low mechanical properties, and several types of research are being conducted to enhance its mechanical properties [ 11 ].…”

Aggressive Impacts Affecting the Biodegradable Ultrathin Fibers Based on Poly(3-Hydroxybutyrate), Polylactide and Their Blends: Water Sorption, Hydrolysis and Ozonolysis

“…Hydrolytic degradation of PHB and PLA films and membranes has been considered in comprehensive detail in the works of Bonartsev et al [ 21 , 22 ]; Arrieta, Kenny et al [ 23 , 24 , 25 ]; Cameron et al [ 26 ]; and many other prominent authors; see, e.g., [ 27 , 28 , 29 , 30 , 31 , 32 ]. Note that the acid hydrolysis mechanism for the ester functional groups is significantly different from the process in the alkaline medium [ 38 , 39 ].…”

“…At the microscopic level, in films and membranes, hydrolysis and enzymatic degradation of biopolyesters such as PHB and PLA as well as their blends have been comprehensively outlined in many recent publications [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. Diffusion phenomena and catalytic reactions in the samples at the micro/macro scale were experimentally collected and modeled via kinetic simulations to elucidate the degradation mechanisms and evaluate the exploitation lifespans of the biodegradable materials [ 24 , 25 , 26 , 27 ].…”