Effects of NANH as nucleation agent on performances of PLLA

Abstract

In this research, NANH as a new synthetic organic nucleating agent was employed to overcome PLLA’s slow crystallization rate. Melt-crystallization showed that PLLA’s crystallization ability was significantly enhanced by NANH, even that NANH was still able to evidently accelerate PLLA’s crystallization upon cooling rate of 50 °C/min. Additionally, when the final melting temperature was 170°C, the onset melt-crystallization temperature and melt-crystallization peak temperature of PLLA/3%NANH were up to 160.0 °C and 155.1 °C. Isothermal crystallization showed that the half time of overall crystallization of PLLA/3%NANH was dramatically reduced, from 71.9 min at 135 °C for the virgin PLLA, to the minimum value of 0.3 min, and this advanced nucleation effect was speculated to be attributed to chemical nucleation via the theoretical analysis of frontier orbital energy. Melting behaviors under different conditions further confirmed the crystallization accelerating effect of NANH for PLLA’s crystallization, and the melting processes were affected by crystallization temperature and heating rate. Although NANH decreased PLLA’s thermal decomposition temperature in air, thermal decomposition temperatures of all PLLA/NANH were higher than 330 °C, which could meet the daily usage. Finally, the addition of NANH enhanced PLLA’s fluidity, however, the light transmittance was seriously weakened.