Highly flame retardancy, barrier, mechanical and persistent antibacterial polylactic acid film with high-parallel interconnected thousand layered cake architecture

• Published in: International journal of biological macromolecules 2024-07, Vol.273 (Pt 1), p.132777, Article 132777
• Main Authors: Tang, Dongfang, Qin, Zuodong, Luo, Xiaofang, Yang, Hua, Liao, Yunhui, Liu, Kuo, Ding, Hongru, Tang, Wufei
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - pharmacology; Bio-based materials; Chitosan - chemistry; Flame retardancy; Flame Retardants; Gelatin - chemistry; Mechanical Phenomena; Polyesters - chemistry; Polylactic acid film; Polyvinyl Alcohol - chemistry; Staphylococcus aureus - drug effects
• ISSN: 0141-8130; 1879-0003; 1879-0003
• DOI: 10.1016/j.ijbiomac.2024.132777

In this work, a bio-based material (CGP) is obtained by combing chitosan, gelatin and polyvinyl alcohol through a simple solution mixing to simultaneously address polylactic acid film (PLA)' flammability and poor barrier, toughness and antibacterial properties by soaking. The results of open fire testing show that modified PLA films can effectively prolong the combustion time, improve the thermal stability and reduce the release of heat in the cone calorimeter test. For the PLA sample after soaking for 5 times (PLA-5) in particular, it can reduce the peak heat release rate (pHRR) and total heat release (THR) values to 85.8 kW/m2 and 1.3 MJ/m2 from the values of 129.5 kW/m2 and 1.8 MJ/m2 for PLA, respectively. Structural analysis suggests that CGP primarily operates in the condensed phase by forming physical barriers. Meanwhile, the modified PLA films can exhibit superior barrier effects, which indicate the oxygen transmission rate value of PLA-5 decreases to 0.9 cm3/(m2·day) from the 392.5 cm3/(m2·day) of raw PLA film. Moreover, the PLA-5 also have excellent toughness (the value increased to 200.5 % from 31.0 %) and persistent antibacterial effects (it still has 100 % sterilization after 500 days). •A bio-based multi-functional coating (CGP) was fabricated and coated on the PLA film.•CGP (average thickness was 1.26 μm) could as a fire shield for underlying substrates.•The flame-retardant mechanism was deeply studied of PLA-5.•PLA-5 strain was obviously enhanced vis-à-vis PLA, and the reason was deeply studied.•CGP can endow PLA with excellent properties of barrier and persistent antibacterial.