Crosslinking assisted fabrication of ultrafine poly(vinyl alcohol)/functionalized graphene electrospun nanofibers for crystal violet adsorption

This article reports the fabrication of water‐stable electrospun mats made from water‐soluble poly(vinyl alcohol) and comprising ultrafine nanofibers for a high surface area to volume ratio as required for the adsorption of crystal violet. Acid‐catalyzed crosslinking is uniquely demonstrated as a facile strategy to improve water stability and, just as importantly, fine‐tune the nanofiber size of the electrospun mats. Amine‐functionalized graphene nanoplatelets are incorporated as an adsorption performance enhancer instead of the more widely reported graphene oxide. The functionalized graphene also facilitates fabrication of the composite electrospun mats by direct mixing of the water‐dispersible graphene with the aqueous polymer solution. The enhanced adsorption performance of the polymer nanocomposite mats is explained in detail at the molecular level, while the adsorption mechanism is supported by adsorption isotherm and related kinetic data. Moreover, the adsorbent mats can be removed from the water after use with the mat integrity still maintained. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46318.     

Shelf life extension of fresh asparagus using modified atmosphere packaging and vacuum skin packaging in microwavable tray systems

Asparagus (Asparagus officinalis L.) is one of the most popular vegetables because it contains a wealth of fiber and several essential nutrients. It is a very perishable commodity due to its very high respiration rate. To maintain product quality and to satisfy consumer demand as a convenient food, modified atmosphere packaging (MAP), vacuum skin packaging (VSP), and microwaveable containers were used to extend the shelf life of fresh-cut asparagus as a ready-to-eat food product. The objective of this study was to determine the shelf life of fresh-cut asparagus packed in MAP and VSP microwaveable tray systems at commercial storage conditions, 4°C, 80% RH. Weight loss, moisture content, O₂/CO₂ concentration in the package headspace, product pH, microbial growth, and sensory evaluation were used to determine the product quality and shelf life. Moreover, the preference of product appearance and the quality of the cooked asparagus in both microwaveable tray systems at different cooking times and microwave power levels was also sensorially evaluated. During storage for 21 days, there was no significant difference (p > 0.05) in weight loss, moisture content, and pH. Sanitation and packaging techniques also helped to retard the microbial growth. Both techniques, combined with refrigeration, help to maintain the freshness and product shelf life up to 21 days for MAP and 18 days for VSP. On the basis of hedonic scale results, consumers preferred the appearance of both packaging types. Both microwavable tray systems, thus, can help to prolong the shelf life of fresh-cut asparagus and can be eaten directly from the package.     

Electrospinning polymer blend of PLA and PBAT: Electrospinnability–solubility map and effect of polymer solution parameters toward application as antibiotic‐carrier mats

Electrospinning of a biodegradable polymer blend of poly(lactic acid) (PLA) and poly(butylene adipate‐co‐terephthalate) (PBAT) is reported for the first time. Effects of several solution parameters on electrospinning are explored, including types of single and binary solvents, binary solvent mixing ratio, polymer blend concentration, polymer blending ratio, and loading content of tetrabutyl titanate as a compatibilizer. An electrospinnability–solubility map of the PLA/PBAT blend is firstly developed for the facile selection of a suitable binary solvent system, thus simplifying the laborious, time‐consuming, trial‐and‐error process. A particular binary solvent system derived from good and non‐solvent serves as the most suitable medium for the successful preparation of homogeneous bead‐free electrospun PLA/PBAT nanofibers. It is revealed that the compatibilizer acts not only as a diameter size tuner for the PLA/PBAT fibers but also as a mechanical property enhancer for the immiscible PLA/PBAT electrospun mats. Moreover, the antibacterial activity of the drug‐loaded PLA/PBAT fibrous mats suggests their potential application as antibiotic‐carrier mats. Preparation of the composite mats comprising bead‐free fibers with an average size at sub‐micrometer scale is also demonstrated, additionally promoting the possibility of using the PLA/PBAT‐based electrospun mats as a matrix of various additives for a wide range of applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46486.     

Formulation and characterization of compatibilized poly(lactic acid)‐based blends and their nanocomposites with silver‐loaded kaolinite

Biodegradable polymer nanocomposites have been developed in this study as materials for use in the packaging of moisture‐sensitive products. Poly(lactic acid) (PLA) was the main component of the nanocomposites with poly(butylene adipate‐co‐terephthalate) (PBAT) as flexibility enhancer. Tetrabutyl titanate was also added as a compatibilizer to enhance the interfacial affinity between PLA and PBAT by inducing the formation of some PLA/PBAT via transesterification during the melt blending process, thereby improving the mechanical properties of the blends. Silver‐loaded kaolinite synthesized via chemical reduction was also incorporated into the compatibilized blends for further property improvement. Herein, we report a novel biodegradable quaternary nanocomposite system with intercalated‐exfoliated clay dispersion that was uniquely achieved by increasing the interlamellar space between kaolinite layers through silver nanoparticle insertion. The resultant nanocomposites containing as little as 4 phr modified clay reduced the elongation at break from 213.0 ± 5.85% to 53.8 ± 1.81%, enhanced thermal stability (initial decomposition temperature increased from 378 °C to 399 °C) and exhibited a water vapor permeability reduction of 41.85%. On the basis of these properties, the developed nanocomposites are considered to be promising candidates for use in bio‐packaging applications to replace non‐biodegradable and petro‐based plastics. © 2014 Society of Chemical Industry