Controlled Degradation of PBAT for PBAT/PLA Blend Melt-Blown Nonwovens

This study utilized the chain-scission capability of peroxides, such as aqueous hydrogen peroxide (H₂O₂), to induce controlled degradation of poly(butylene adipate-co-terephthalate)(PBAT) through reactive batch mixing with the objective of increasing the melt flow index (MFI). The effects of the peroxide concentration and processing time were examined, and the results showed that concentration had the greatest impact, with an approximate 450% increase in MFI at the optimal peroxide concentration. On the other hand, the peroxide treatment had a minimal impact on crystallinity and thermal properties. Degradation was deemed to occur chiefly via random chain scission with contributions from heat and hydrolysis, as supported by proton nuclear magnetic resonance spectroscopy (⁺HNMR). The treated PBAT sample showed promise in melt-blown micro-fiber production, producing fibers with a 68% smaller average diameter than that of the untreated PBAT. The treated PBAT was then blended with various levels of high MFI poly(lactic acid) (PLA) to optimize properties and cost of the resulting micro-fiber material. As expected, the blends demonstrated increased tensile strength and decreased elongation at break with higher PLA contents, up to 30% and 13%, respectively, successfully balancing the material properties of the PBAT starting material. Despite these favorable tensile properties, the material blend remained suboptimal due to evidence of phase separation. To bridge this incompatibility, maleation was implemented, resulting in a polymer characterized by improved homogeneity, thereby enabling the production of uniform fibers without compromising desired tensile properties. The melt-blowing generated PBAT-PLA micro-fibers can have applications as a sustainable alternative for polypropylene-dominated HVAC air filters, medical masks, etc.