Effect of birch tar embedded in polylactide on its biodegradation

Area of Science:

• Polymer Science and Engineering
• Environmental Science and Microbiology
• Materials Science

Background:

• Polylactide (PLA) is a biodegradable polymer with potential applications in packaging.
• Incorporating additives like birch tar can enhance PLA's properties, such as antimicrobial activity.
• Understanding the end-of-life biodegradation of such composite materials is crucial for sustainable applications.

Purpose of the Study:

• To characterize the biodegradation of polylactide (PLA) films plasticized with birch tar (BT).
• To evaluate the impact of birch tar concentration on PLA film properties and biodegradability.
• To assess the effectiveness of bioaugmentation using specific microbial strains for enhanced PLA-BT film degradation.

Main Methods:

• Preparation of PLA films with varying birch tar concentrations (1%, 5%, 10%).
• Assessment of biodegradation through biological oxygen demand (BOD21) and compost degradation studies.
• Characterization of film properties using scanning electron microscopy (SEM), water vapor permeability (Pv), and oxygen permeability (Po).
• Isolation and identification of microbial strains (Bacillus toyonensis AK2, Bacillus albus AK3) for bioaugmentation.

Main Results:

• PLA films with birch tar demonstrated antimicrobial properties.
• The identified microbial consortium significantly increased the susceptibility of PLA-BT films to biodegradation in compost.
• Biodegradation led to changes in physicochemical properties, including biofilm formation and reduced barrier properties (Pv, Po).
• SEM analysis confirmed surface changes indicative of microbial degradation.

Conclusions:

• PLA films plasticized with birch tar are suitable for the packaging industry.
• Intentional biodegradation processes, including bioaugmentation with Bacillus toyonensis AK2 and Bacillus albus AK3, can effectively degrade these materials post-use.
• This approach offers a sustainable end-of-life solution for PLA-based packaging.