Macromolecular Research, Vol.31, No.2, 105-120, February, 2023
Characterization of rheological behavior and barrier property of PET bottle blended with silica–polystyrene nanocomposites
A PET nanocomposite was prepared as master batch by blending with 0.5 wt% of SiOx–PS nanoparticles via melt mixing using a twin screw extruder at 200 °C, 210 °C and 220 °C melting temperatures. The functional master batch was used to manufacture SiOx–PS (polystyrene)/PET bottle by blow molding method. The spherical SiOx–PS nanoparticle with a diameter of ~ 320 nm and surface charge value of − 22.1 mV were dispersed within the inner surface of the SiOx–PS/PET bottle. Rheological studies showed that the terminal zone slope of G′ changed along with the melting temperature, while that of the loss modulus (Gʺ) maintained the value of Gʺ ~ ω1 for all samples. The values were G′ ~ ω1.5 for pristine PET and G′ ~ ω1.4 for 200 °C/220 °C, while the nanocomposite prepared at 210 °C showed slightly increased G′ ~ ω1.6. The shear-thinning behavior was determined during frequency sweep test and showed that viscosity decreased with increase in the shear rate. The shear-thinning of pristine PET and SiOx–PS/PET was significant at lower shear rate but decreased monotonously at higher shear rate over 10 s−1. The CO2 retention of SiOx–PET bottle prepared at 210 °C showed the highest barrier property (87.1%), while pristine PET (77.6%) and other bottles provided retention of 85.7% (200 °C) and 86.0% (220 °C). Our results demonstrated that the SiOx–PS nanocomposite prepared at 210 °C induced homogeneous dispersion of nanoparticles on the inner surface of the SiOx–PS/PET bottle which improved barrier property by inhibiting the diffusion of CO2 gas molecules.