The study proposes a new green extraction method of producing nano fibrillated cellulose (NFC) from softwood pulp (SWP) by using subcritical water/CO 2 . Subcritical water/CO 2 led to a controlled hydrolysis of SWP and the treated SWP was fibrillated by sonication to produce NFC. Effect of process parameters (time, temperature, and pressure) on the crystallinity and thermal properties of NFC was studied to optimize the process conditions for controlled hydrolysis. The influence of the extraction process on the properties of prepared NFC was studied. Nanocellulosic materials were characterized by using field emission scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, wide-angle X-ray diffraction, and thermo gravimetric analysis. The NFC obtained at optimum process conditions (100 bar, 145 C, and 30 min) showed significantly high crystallinity (66%) and high yield (75-80%) compared to the NFC prepared by conventional mechanical grinding method. The present method of producing NFC uses water and pressurized CO 2, and therefore, eliminate use of acids and chemicals. Plasticized poly vinyl alcohol (p-PVA) based nano composite with NFC shows significant improvement in thermal stability (36%), tensile strength (77%) with reduced water vapor transmission rate as compared to virgin p-PVA indicating their potential as nanofiller for making bio composites.
Responsive packaging systems can adapt to surrounding environments or react to stimuli in the food and/or regulate transport of encapsulated actives/nutrition in presence of external stimuli. It also converts chemical and biochemical signals into optical, electrical, mechanical signals etc. To allow real time food safety and quality monitoring along with extension of shelf-life of food products. These packaging systems are currently an emerging area in food packaging research and playing an increasingly important part in a diverse range of applications, such as nutrition delivery in controlled fashion, 'on demand' active delivery, spoilage indicators etc. This paper gives an overview of recent developments and challenges on the applications of stimuli-responsive materials towards food packaging area. We also highlight the future directions to convert research outcome into commercial products.
An ecofriendly and biodegradable porous structure was prepared from drying aqueous foams based on nano fibrillated cellulose (NFC), extracted from softwood pulp by subcritical water/CO 2 treatment (SC-NFC). The primary aim of this work was to use the modified SC-NFC as stabilizer for a water-based Pickering emulsion which upon drying, yielded porous cellulosic materials, a good dye adsorbent. In order to exploit the carboxymethylated SC-NFC (CMSC-NFC, with a degree of substitution of 0.35 and a charge density of 649 μeqv/g) as a stabilizer for water-based Pickering emulsion in subsequent step, an optimized quantity of octyl amine (30 mg/g of SC-NFC) was added to make them partially hydrophobic. A series of dry foam structures were prepared by varying the concentrations of treated CMSC-NFCs and 4 wt% was found to be the optimum concentration to yield foam with high porosity (99%) and low density (0.038 g/cc) along with high compression strength (0.24 MPa), superior to the conventionally extracted NFC. The foams were applied to capture as high as 98% of methylene blue dyes, making them a potential green candidate for treating industrial effluent. In addition, the dye adsorption kinetics and isotherms were found to be well suited with second order kinetics and Langmuir isotherm models.
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