The Structure and Properties of Biodegradable PLLA/PDLA for Melt-Blown Nonwovens

Poly(l-lactic acid) (PLLA) and poly(d-lactic acid) (PDLA) blends with various compositions, utilized for melt-blown nonwovens, were prepared by a melt blending method. Their structure and properties were investigated by differential scanning calorimetry, thermal mechanical analyzer (DMA), X-ray diffraction, polarized optical microscope, field emission scanning electron microscope, and a universal testing machine, respectively. The results showed that the addition of PDLA decreased the glass transition temperature of PLLA. The PLLA/PDLA blends with the 0.3 % PDLA had the lowest the melting temperature and the degree of crystallization. The growth rate and size of the spherulites of the blends increased with the increase of the PDLA content. PLA stereocomplex could be achieved in the PLLA/PDLA blends. PDLA phase was dispersed uniformly in PLLA matrix in the formation of small circular particles. An increase of the PDLA content resulted in the improvement of the fracture toughness of the blends. When the PDLA content was 0.3 %, the blends achieved the highest elongation at break and toughness. Moreover, PDLA had a positive effect on the enhancement of the toughness of PLLA/PDLA melt-blown nonwovens.