Polystyrene/Polyolefin Elastomer Blends Loaded with Halloysite Nanotubes: Morphological,Mechanical, and Gas Barrier Properties

Herein, a simple melt-blending method is utilized to disperse of halloysite nanotubes (HNTs) in polystyrene/polyolefin elastomer (PS/POE) blends. Based on morphological studies, the PS/POE/HNT nanocomposite containing up to 3 phr HNTs shows excellent nanofiller dispersion, while those filled with 5 phr HNTs exhibit nanofiller aggregation. To overcome the nanofiller aggregation issue, the polypropylene-grafted-maleic anhydride (PP-g-MA) compatibilizer is added to the PS/POE/HNT nanocomposite, which results in improved mechanical properties for the nanocomposite sheets. Furthermore, the addition of compatibilized HNTs to the PS/POE blends leads to decreased O₂ and N₂ gas permeabilities. Besides, incorporating POE, HNTs, and PP-g-MA leads to a decrease in water vapor transmission of PS. In the end, the experimentally-determined mechanical properties and gas permeabilities of the nanocomposite sheets are compared to those predicted by prevalent theoretical models, revealing a good agreement between the experimental and theoretical results. Molecular-dynamics simulations are also carried out to calculate the gas diffusion coefficients in the different sheets to further support the experimental findings in this study. Overall, the PS/POE/HNT/PP-g-MA nanocomposite sheets fabricated in this work demonstrate excellent mechanical and gas barrier properties; and hence, can be used as candidate packaging materials. However, the strength of the resulting PS/POE blend may be inferior to that of the virgin PS.     

In-depth study of mechanical properties of poly(lactic acid)/thermoplastic polyurethane/hydroxyapatite blend nanocomposites

Journal of Materials Science - The present study evaluates the effect of adding different contents of hydroxyapatite (HA) nanoparticles on the mechanical properties of poly(lactic...     

Toughening of epoxy resin systems using core–shell rubber particles: a literature review

Journal of Materials Science - Excellent thermal and mechanical properties and high chemical resistance with low shrinkage of epoxy resins open a wide window of various industrial applications,...     

Qualitative and Quantitative Changes in the Essential Oil of Lemon Verbena (Lippia citriodora) as Affected by Drying Condition

The objective of this study was to evaluate the effect of drying air temperature and air flow rate on the quantity and quality of the essential oil of lemon verbena. A completely randomized design was applied with a factorial arrangement of two factors: temperature (30, 40, and 50°C) and air flow rate (0.5, 1, and 1.5 m/s). The leaves were harvested in full blooming stage and placed in the drying machine at different temperatures and air flow rates. The essential oil of leaves was extracted by hydrodistillation in a Clevenger apparatus and analyzed by gas chromatography (GC) and gas chromatography–mass spectrometry (GC-MS). The results showed that the interaction between different temperatures under various air flow rates had a significant effect on the content and chemical composition of the essential oil. Seventeen compounds were identified in essential oil of lemon verbena, of which geranial, neral, and limonene were the major components. The maximum oil content and majority compounds of essential oil were obtained at 50°C and a 0.5 m/s air flow. Finally, seven mathematical models of thin-layer drying such as correlation coefficient (R ²), sum of square errors (SSE), and root mean square error (RMSE) were evaluated and the modified Page model was found to be the best drying model for lemon verbena.