Cellulose Blended Membranes for High-Salinity Water Pervaporation Desalination

In the current study, cellulose acetate (CA)/cellulose triacetate (CTA) nanocomposite membranes blended with zirconium dioxide (ZrO2) are prepared via phase inversion for pervaporation desalination performance. ZrO2 nanoparticles are added to enhance the hydrophilicity and porosity of the nanocomposite membranes. The fabricated nanocomposite membranes are characterized by SEM, FTIR, TGA, and DSC to study the surface morphology, chemical composition, thermal stability and strength. Nanocomposite membranes’ performance for pervaporation desalination is assessed as a function of feed concentration. Pervaporation results revealed that the nanocomposite membrane consisting of 2% ZrO2 achieved a maximum water flux of 6.5 kg/m2h, whereas the salt rejection was about 99.8%.

Thermal Stability and Crystallization Behavior of Contaminated Recycled Polypropylene for Food Contact

Polypropylene is one of the most widely used polymers, especially in the food packaging industry, which causes negative environmental effects. Recycling is a good option to partially solve this environmental problem. Thus, the polymer was contaminated with a cocktail to simulate the conditions of disposal and recycling following FDA guidelines. The influence of contaminants on recycled PP was analyzed by quiescent and nonquiescent crystallization. It was found that the contaminants alter the crystallization flow since longer induction times were observed for all contaminated samples. Also, the thermal behavior was performed considering that the thermogravimetric (TGA) results indicated an increase in the stability with the presence of contaminants. Therefore, a deep investigation using the induced oxidation time (OIT) and induced oxidation temperature (OITD) was performed. The contaminants play an important role in the crystallization process, as well as, in the degradation of the samples. Furthermore, the use of TGA and DSC as complementary techniques is fundamental to analyze this influence.

A comparative study of greener alternatives for nanocellulose production from sugarcane bagasse

Use of enzyme for extraction of nanocellulose from sugarcane bagasse is greener alternative. Literature indicates that effectiveness of these enzymes can be improved by auxiliary enzymes or mediators. In the current study, extraction of nanocellulose using laccase with these moderators, auxiliary enzyme glucose oxidase and mediator molecule, ABTS [2,2′-azinobis(3-ethylbenzthiazoline-6-sulfonate)] individually was done. Cellulose and lignin content, FT-IR, TGA and DSC analysis, XRD, SEM and PSA were done. Enzyme moderators improved the performance of laccase in lignin degradation. Lignin and cellulose content, crystallinity were used as parameters to optimize the concentrations, which was found to be ABTS (at 1.4 mM) and glucose oxidase (at 0.15 mg ml−1). At the optimal concentration, nanocellulose was extracted. Properties of nanocellulose obtained from both routes were compared. Size analysis revealed 339 nm and 636 nm for nanocellulose obtained with glucose oxidase and ABTS, respectively. Defibrillation was better in the case of the former one as seen from SEM. Graphical Abstract

Cloisite 20A Based Polyaniline Nanocomposites for Nitrogen Dioxide (No2) Gas Sensors

Compacted polyaniline (PANI)/Layered silicate nanocomposites have been successfully prepared by simple in situ, core-shell, and ex situ polymerization routes using AnHCl as a predecessor through chemical oxidation method. The structure, chemical groups, electronic transition and properties were investigated by XRD, SEM, HRTEM, UV Visible, DC electrical conductivity, TGA, and DSC. The XRD results reveals that HCl-treated Cloisite 20A, and PANI-ES/Cloisite 20A nanocomposites are delaminated. Flake-like morphologies were observed in Cloisite 20A and HCl-treated Cloisite 20A, whereas different rate of compacted fibrous morphologies of prepared PANI-ES/Cloisite 20A nanocomposites were observed as evident from SEM images. The Si-O FTIR band position does not change even after HCl treatment of Cloisite 20A, but different FTIR peaks positions of PANI-ES/Cloisite 20A nanocomposites were shifted from pure PANI-ES peaks after using Cloisite 20A nanoclays. UV-Visible spectra indicated the increment of charge carrier within the PANI-ES/Cloisite 20A nanocomposites compared to the pure one. The prepared nanohybrids showed significantly improved thermal property compared to pristine PANI-ES as clear from TGA and DSC analysis. The highest DC electronic conductivity of nanocomposite prepared by core-shell route is found to be 5.12 S/cm using linear four probe techniques. In addition, the charge transport mechanism was understood with and without loading Cloisite 20A in PANI-ES. The conductivity data supported the temperature-dependence relationship σ(T) = σ0.exp[-To/T)1/4] and followed characteristic of three-dimensional variable-range hopping (3D‒VRH) mechanism. In addition, we were discussed the response of Nitrogen dioxide (NO2) gas with polyaniline based sensor materials.

Effect of Silver Nanopowder on Mechanical, Thermal and Antimicrobial Properties of Kenaf/HDPE Composites

This study aims to investigate the effect of AgNPs on the mechanical, thermal and antimicrobial activity of kenaf/HDPE composites. AgNP material was prepared at different contents, from 0, 2, 4, 6, 8 to 10 wt%, by an internal mixer and hot compression at a temperature of 150 °C. Mechanical (tensile, modulus and elongation at break), thermal (TGA and DSC) and antimicrobial tests were performed to analyze behavior and inhibitory effects. The obtained results indicate that the effect of AgNP content displays improved tensile and modulus properties, as well as thermal and antimicrobial properties. The highest tensile stress is 5.07 MPa and was obtained at 10wt, TGA showed 10 wt% and had improved thermal stability and DSC showed improved stability with increased AgNP content. The findings of this study show the potential of incorporating AgNP concentrations as a secondary substitute to improve the performance in terms of mechanical, thermal and antimicrobial properties without treatment. The addition of AgNP content in polymer composite can be used as a secondary filler to improve the properties.

Chain Extension of Poly(Lactic Acid) (PLA)–Based Blends and Composites Containing Bran with Biobased Compounds for Controlling Their Processability and Recyclability

The present work focused on the research, design, and study of innovative chain extender systems of renewable origin for PLA–based biocomposites, reinforced with wheat bran as filler. The majority of employed chain extender compounds belongs to fossil world, affecting the biodegradability property which characterizes biopolymers. The aim of this work was thus to find promising biobased and sustainable alternatives to provide the same enhancements. According to this objective, epoxidized soybean oil (ESO) was chosen as principal component of the chain extender systems, together with a dicarboxylic acid, malic acid (MA), or succinic acid (SA). The reactivity of the modifier systems was previously studied through thermogravimetric analysis (TGA) and IR spectroscopy, to hypothesize the reaction mechanism in bran–filled blends. Hence, small–scale extrusion was carried out to investigate the effects of ESO/MA and ESO/SA on formulations of different composition (both pure PLA blends and composites). The variation of melt fluidity parameters was analyzed to define the optimized concentration of modifier systems. A comparison between the effects on blends of designed biobased systems and the action of fossil–based Joncryl was performed, to understand if the developed green solutions could represent competitive and efficient substitutes. The modified composites were characterized in terms of mechanical tests, degradation and thermal studies (TGA and DSC), and morphological analysis (SEM), to figure out their main features and to understand their potential in possible industrial applications.

Strong Polyamide-6 Nanocomposites with Cellulose Nanofibers Mediated by Green Solvent Mixtures

Cellulose nanofiber (CNF) as a bio-based reinforcement has attracted tremendous interests in engineering polymer composites. This study developed a sustainable approach to reinforce polyamide-6 or nylon-6 (PA6) with CNFs through solvent casting in formic acid/water mixtures. The methodology provides an energy-efficient pathway towards well-dispersed high-CNF content PA6 biocomposites. Nanocomposite formulations up to 50 wt.% of CNFs were prepared, and excellent improvements in the tensile properties were observed, with an increase in the elastic modulus from 1.5 to 4.2 GPa, and in the tensile strength from 46.3 to 124 MPa. The experimental tensile values were compared with the analytical values obtained by micromechanical models. Fractured surfaces were observed using scanning electron microscopy to examine the interface morphology. FTIR revealed strong hydrogen bonding at the interface, and the thermal parameters were determined using TGA and DSC, where the nanocomposites’ crystallinity tended to reduce with the increase in the CNF content. In addition, nanocomposites showed good thermomechanical stability for all formulations. Overall, this work provides a facile fabrication pathway for high-CNF content nanocomposites of PA6 for high-performance and advanced material applications.

Smart Hydrogels: Preparation, Characterization, and Determination of Transition Points of Crosslinked N-Isopropyl Acrylamide/Acrylamide/Carboxylic Acids Polymers

Smart hydrogels (SH) were prepared by thermal free radical polymerization of N-isopropyl acrylamide (NIPAAm), acrylamide (AAm) with acrylic acid (A) or maleic acid (M), and N, N′-methylene bisacrylamide. Spectroscopic and thermal characterizations of SHs were performed using FTIR, TGA, and DSC. To determine the effects of SHs on swelling characteristics, swelling studies were performed in different solvents, solutions, temperatures, pHs, and ionic strengths. In addition, cycle equilibrium swelling studies were carried out at different temperatures and pHs. The temperature and pH transition points of SHs are calculated using a sigmoidal equation. The pH transition points were calculated as 5.2 and 4.2 for SH-M and SH-A, respectively. The NIPAAm/AAm hydrogel exhibits a critical solution temperature (LCST) of 28.35 °C, while the SH-A and SH-M hydrogels exhibit the LCST of 34.215 °C and 28.798 °C, respectively, and the LCST of SH-A is close to the body. temperature. Commercial (CHSA) and blood human serum albumin (BHSA) were used to find the adsorption properties of biopolymers on SHs. SH-M was the most efficient SH, adsorbing 49% of CHSA while absorbing 16% of BHSA. In conclusion, the sigmoidal equation or Gaussian approach can be a useful tool for chemists, chemical engineers, polymer and plastics scientists to find the transition points of smart hydrogels.