Hydrogen Peroxide-Induced\nControlled Degradation of\nPoly(lactic acid) for Melt-Blown Nonwovens

This study aimed to increase the melt flow index (MFI)\nof poly(lactic\nacid) (PLA) through aqueous hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>)-induced degradation. From this work, the impacts of hydrogen\nperoxide concentration and processing time were examined with samples\nthat were prepared through reactive melt batch mixing. The hydrogen\nperoxide treatment and change in processing times were shown to decrease\nmolar mass (<i>M</i><sub>W</sub>) to various degrees, up\nto 70%. Overall crystallinity was only decreased with lower peroxide\nconcentrations, while the glass transition temperature was reduced\nby 4 to 11% among all treated samples. Results confirm degradation\nvia random chain scission with additional contributions from heat,\nhydrolysis, and potential alcoholysis. All results concur with the\nfinding that lower peroxide concentrations paired with longer processing\ntimes result in the most effective degradation, while higher peroxide\nconcentrations begin to favor cross-linking as processing time continues,\nresulting in increased <i>M</i><sub>W</sub>. Therefore,\nlower peroxide concentrations are recommended for greater control\nover the extent of degradation. The resulting high MFI PLA can have\napplications that require low viscosity, such as melt-blown nonwoven\nmaterials where the treated sample was shown to produce finer, more\nuniform fibers at lower operating temperatures compared to raw PLA.