Effect of molecular weight on the properties and structure of biodegradable poly-lactic acid melt-blown nonwovens

Biodegradable poly-lactic acid (PLA) with varying molecular weights of melt-blown nonwovens was successfully prepared through the method of melt spinning. The phase morphology, rheological behavior, hydrophobicity, and crystalline characteristics of the melt-blown nonwovens have been investigated. The thermal and crystallization behavior revealed that PLA samples with low molecular weights, resulted in a higher degree of crystallinity, meanwhile, the polarized optical microscopy (POM) analysis demonstrates that the large spherical crystal size was obtained with low molecular weights within the same crystallization time. For another, the storage modulus ( G ′), loss modulus ( G ′′), and complex viscosity | η *| were increased with the increase in molecular weight from rheological measurement. The morphologies of fiber were observed by SEM, the average diameter increased from 11.86 to 21.07 μm. Furthermore, the water contact angle (WCA) of nonwoven decreased from 128.9° to 114.9° due to an increase in viscosity led to an increase in the distribution of fiber diameters.