Influence of different β-nucleation agents on poly(L-lactic acid): structure, morphology, and dynamic mechanical behavior

The effects of rare earth based beta-nucleating agent (WBG-II) and aryl amide derivative nucleating agent (TMB-5000) on the crystal structure, morphology, and dynamic mechanical behavior of poly(L-lactic acid) (PLLA) were systematically investigated. The presence of beta-form crystal in PLLA composites has been confirmed through various techniques including wide-angle X-ray diffraction (WAXD), Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy. The crystallization behaviors of WBG-II and TMB-5000 nucleated PLLA were studied via WAXD and polarized optical microscope (POM) techniques. The experimental results convincingly reveal that WBG-II and TMB-5000 not only accelerate the crystallization rate, but also alter the packing structure of PLLA chains in the crystals. Furthermore, a significant difference in crystal dimensions and nucleation density was observed clearly. Moreover, the effect of different beta-nucleating agents on the storage modulus (E') and dynamic loss (tan delta) of pure PLLA, PLLA/TMB-5000(0.25) and PLLA/WBG-II0.25 were investigated by dynamic mechanical analysis (DMA).