To investigate the effect of modified graphene (Gra) by poly(methoxy poly(ethylene glycol) monomethacrylate-co-1-vinyl-3-ethylimidazolium bromide) (P[MPEGMA-IL]) on crystallization and dielectric behavior for poly(lactic acid) (PLA), the neat PLA and its composites were fabricated via solution blending and hot pressing. P[MPEGMA-IL] can improve the dispersibility of Gra in PLA matrix. The crystallization rate of PLA composites was increased with increasing the content of P[MPEGMA-IL] and Gra due to the plasticizing effect of P[MPEGMA-IL] and the nucleating effect of better-dispersed Gra. In the frequency spectra of PLA composites treated by cold crystallization process, α relaxation and interfacial polarization resulted in high values of dielectric permittivity. The incorporation of modified Gra into the matrix can accelerate interfacial polarization. The effect of modified Gra on charge carrier movement mechanism was resulted from the increase of the mobile charge carriers at the interphase and the dielectric strength of interfacial polarization.
Dielectric relaxation spectroscopy (DRS) was used to investigate the effect of morphological evolution on conductivity behavior of PLA/PCL blends containing P[MPEGMA-IL]. The morphology of blends changes from sea-island morphology into co-continuous morphology with increasing P[MPEGMA-IL] content. P[MEPGMA-IL] could mainly localize in PCL domains and expand to the interface layer between the PLA and PCL phase because of the low viscosity of PCL phase and the high affinity of MEPGMA groups for both polymer phases. The dielectric results were discussed in terms of α relaxation that corresponds to normal and segmental mode movement, interfacial polarization that corresponds to interfacial aggregation of charge carriers, and ac conductivity that originates from conductive network of mobile charge carriers. Co-continuous morphology and high ions concentration lead to the enhancement of segment movement and ion conductive channel in PCL phase, which correspond to high conductivity and low activation energy of PLA/PCL/8P[MEGMA-IL] blend.
危险品化学品经营许可证（带存储）