Preparation and characterization of poly(propylene carbonate)/exfoliated graphite nanocomposite films with improved thermal stability, mechanical properties and barrier properties

Abstract

Relatively high aspect ratio exfoliated graphite (EFG) particles with an average size of 7.4 µm and a nanometer sized thickness of 30-50 nm were successfully prepared by thermal treatment at 1050• C and subsequent ultrasonication for application as a filler to improve the physical properties of eco-friendly poly(propylene carbonate) (PPC). A series of poly(propylene carbonate)/exfoliated graphite (PPC/EFG) nanocomposite films with different EFG contents were prepared via a solution blending method. The physical properties were strongly dependent upon the chemical and morphological structures originating from the differences in EFG composition. The morphological structures, thermal properties, mechanical properties and barrier properties of the nanocomposite films were investigated as a function of the EFG content. While all of the PPC/EFG nanocomposite films exhibited good dispersion of EFG to some extent, Fourier transform infrared and SEM results revealed that solution blending did not lead to strong interactions between PPC and EFG. As a result, poor dispersion occurred in composite films with a high EFG content. By loading EFG particles, the oxygen permeabilities, moisture permeabilities and water uptake at equilibrium decreased as the EFG content increased. Compared with pure PPC, PPC/EFG nanocomposite films have enhanced molecular ordering. Specifically, the 2% PPC/EFG composite film shows greater molecular ordering than the other composite films, which results in the highest mechanical strength. In future work, the compatibility and dispersion of the PPC matrix polymer and EFG filler particles should be increased by modifying the EFG surface or introducing additives.

Thermal and barrier properties of EVOH/EFG nanocomposite films for packaging applications: Effect of the mixing method

“…However, the effectiveness of EFG in improving the thermal properties fell short of our expectations, which can be ascribed to weak interfacial interactions and a poor dispersion of EFG in EVOH [25].…”

“…In general, T g and T m are strongly dependent on the segmental mobility of polymer chains. Well-dispersed fillers in a polymer matrix can restrict the chain mobility of polymers, specifically under strong interfacial interactions between fillers and the polymer matrix, which can increase the T g and T m of polymer films [4,7,25]. In this study, the EFG nanoparticles possessed greater thermal stability than the polymer matrix and can physically confine the polymer chains, decreasing the polymer chain mobility.…”

Effect of porous zeolite on temperature-dependent physical properties of polypropylene/octadecane (PP/OD) composite films

“…The WAXD data were used to estimate the mean intermolecular distance (d-spacing), crystallinity, and crystal sizes. The dspacings of the PP/OD/ZL composite films were calculated using Equation (1): (1) where n is the reflection order, λ (= 1.5406 Å) is the wavelength of the Cu-Kα X-ray radiation, d is the mean intermolecular distance, and θ is the diffraction angle [2,19,20]. Subsequently, the percent crystallinity (X c, WAXD ) was evaluated from the WAXD data according to Equation (2): (2) where A cryst and A amorp are the integral areas of the crystalline and amorphous peaks for the composite films, respectively [2].…”

“…The increase in the volume fraction of the ZL crystalline phase enhanced the related OD/ZL and PP/ZL interfacial interactions, which constantly maintained the immobilization of the OD species in the composite films during the OD phase change with increasing temperature. Note that the PP and ZL crystalline regions in the films are considered impermeable to oxygen and water vapors due to the formation of tortuous channels that prevent penetrants from sorption and diffusion into the composite films [19,20]. As a result, the permeation jumps for oxygen and water vapors decreases.…”

Nano-developments for Food Packaging and Labeling Applications

“…They are created by dispersing inert nanoscale fillers throughout the polymeric matrix. Many different nanomaterials are used as fillers like silica nanoparticles (Ke et al 2010;Bracho et al 2012), clay nanoplatelets (Ku et al 2004;Schuetz et al 2011), organoclay (Ham et al 2013;Gokkurt et al 2013), graphene (Lee et al 2013;Yousefi et al 2013), polysaccharide nanocrystals , carbon nanotubes (Swain et al 2013;Prashantha et al 2009), cellulose-based nanomaterials (Floros et al 2012;Sandquist 2013), chitosan nanoparticles (Chang et al 2010), and other metal nanoparticles like ZnO 2 (Esthappan et al 2013), colloidal Cu (Cárdenas et al 2009), or Ti .…”