Crystallization, dispersion behavior and the induced properties through forming a controllable network in the crosslinked polyester-SiO_2 nanocomposites

摘要

The poly(ethylene terephthalate) (PET) crosslinked copolymers (G-PET) with glycerol (GC) and their novel nanocomposite samples (GNPET) were reported and investigated. The nanoparticle dispersion behavior was creatively stabilized with the crosslinked network. Several interesting properties and phenomena including the abnormal crystallization behavior of GNPET samples were presented. Results of differential scanning calorimeter proved that the thermal and crystallization behavior of GNPET samples was effectively tuned with GC load. The obviously enhanced crystallization and nanoparticle homogenous dispersion behavior appeared at 2 wt % SiO_2 and 0.2 wt % GC load. Polarized optical microscopy (POM) results showed that the spherulite growth rate of the GNPET samples with 0.1 wt % GC load sharply decreased from 0.0562 to 0.0157 μm s~(-1) with 0.5 wt % GC load. As GC load increased, the spherulite size of GNPET samples decreased greatly so as to be much smaller than that of pure PET nanocomposites. Water absorbing experiments presented that the higher GC load created the lower water diffusion behavior but higher barrier against water, gas, and light. A model was proposed to state the network immobilization effect on the nanoparticle dispersion, and the restraining effect on PET chain mobility and crystal size growth which were related to the above properties.