Biopolymer Blends Research Articles

Design of biodegradable polymer blend electrolytes with decoupled ion motion for EDLC device Application: Electrical and electrochemical properties

In this work, plasticized polymer blend electrolytes (PBEs) that are flexible and have quasi-solid-state properties have been prepared using the casting technique. Herein, we present the manufacture and characterization of biopolymer blend electrolytes based on chitosan (CS) and polyvinyl alcohol (PVA) with decoupled ion motion for EDLC device applications. Electrochemical impedance spectroscopy (EIS) was utilized to analyze the dielectric and ion conduction properties of the produced PBEs. Lithium nitrate (LiNO3) salt was used as an ion provider for the host polymers. With an increase in glycerol plasticizer concentration, both ion conduction and dielectric properties were significantly enhanced. The Argand diagram established that conductivity relaxation dynamics (pure ionic relaxation) is dominant at higher plasticizer concentrations. The highest ionic conductivity of 1.707×10-4 S/cm was recorded for the host medium plasticized with 40 wt% of glycerol, and it has been used as a mediator in the EDLC fabrication. Linear sweep voltammetry (LSV) was used to validate the eligibility of the PBE in terms of stability, and it was shown that the film was stable up to 2.93 V. The dominancy of ions as the main carrier in the prepared electrolyte was confirmed using transference number measurement (TNM) analysis, with tion = 0.922. The CR2032 coin cell type EDLC with activated carbon electrodes and the most conductive PBE film had a significantly high specific capacitance of ∼ 33F/g through the cyclic voltammetry (CV) technique. The efficiency of the fabricated EDLC was remarkable, with an average of about 85% over 1000 cycles. Due to its high energy and power densities (4.5 Wh/kg and 1100 W/kg, respectively), this PBE system is well-suited for EDLC.

High performance biopolymer blend nanocomposites derived from cashew gum/polyvinyl alcohol/boehmite for flexible electronic devices

AbstractThis work reports on a bio‐based polymer blend comprised of polyvinyl alcohol/cashew gum (PVA/CG) embedded with boehmite nanoparticles to tailor the structural, thermal, mechanical properties, and electrical response. The chemical bonding between boehmite and the PVA/CG blend was confirmed by FTIR. The XRD data showed that the nanocomposite films had distinct peaks of boehmite. The SEM images revealed uniformly dispersed morphology at 5 wt% boehmite. The elemental composition of blend nanocomposites was revealed by the EDX analysis. The thermal stability of the blend increases with increasing boehmite, whereas the glass transition temperature decreases. The highest AC conductivity was achieved for PVA/CG/7 wt% boehmite, which was 4.6 times greater than the pure blend. The frequency and temperature‐dependent dielectric constant, modulus and impedance of all films were examined in conjunction with different nanoparticle loadings. Tensile strength and hardness have improved with the addition of boehmite into the PVA/CG blend whereas the elongation at break slightly decreases. The PVA/CG blend had a tensile strength of 31.17 MPa, which increased to 44.66 MPa when 7 wt% boehmite was added. Therefore, eco‐friendly PVA/CG/boehmite films with good thermal stability, mechanical strength, dielectric constant, and conductivity could be a practical green substitute for flexible electronic, charge storage, and electrochemical devices.

Thermoelectric Freeze-Casting of Biopolymer Blends: Fabrication and Characterization of Large-Size Scaffolds for Nerve Tissue Engineering Applications.

Peripheral nerve injuries (PNIs) are detrimental to the quality of life of affected individuals. Patients are often left with life-long ailments that affect them physically and psychologically. Autologous nerve transplant is still the gold standard treatment for PNIs despite limited donor site and partial recovery of nerve functions. Nerve guidance conduits are used as a nerve graft substitute and are efficient for the repair of small nerve gaps but require further improvement for repairs exceeding 30 mm. Freeze-casting is an interesting fabrication method for the conception of scaffolds meant for nerve tissue engineering since the microstructure obtained comprises highly aligned micro-channels. The present work focuses on the fabrication and characterization of large scaffolds (35 mm length, 5 mm diameter) made of collagen/chitosan blends by freeze-casting via thermoelectric effect instead of traditional freezing solvents. As a freeze-casting microstructure reference, scaffolds made from pure collagen were used for comparison. Scaffolds were covalently crosslinked for better performance under load and laminins were further added to enhance cell interactions. Microstructural features of lamellar pores display an average aspect ratio of 0.67 ± 0.2 for all compositions. Longitudinally aligned micro-channels are reported as well as enhanced mechanical properties in traction under physiological-like conditions (37 °C, pH = 7.4) resulting from crosslinking treatment. Cell viability assays using a rat Schwann cell line derived from sciatic nerve (S16) indicate that scaffold cytocompatibility is similar between scaffolds made from collagen only and scaffolds made from collagen/chitosan blend with high collagen content. These results confirm that freeze-casting via thermoelectric effect is a reliable manufacturing strategy for the fabrication of biopolymer scaffolds for future peripheral nerve repair applications.

Cellulose nanocrystals doped silver nanoparticles immobilized agar gum for efficient photocatalytic degradation of malachite green

The present study involves the synthesis of green functional material based on the silver nanoparticle (Ag NPs) doped cellulose nanocrystals (CNC) immobilized agar gum (AA) biopolymer using chemical coprecipitation method. The stabilization of Ag NPs in cellulose matrix and functionalization of the synthesized material through agar gum was analyzed using various spectroscopic techniques such as Fourier Transform Infrared (FTIR), Scanning electron microscope (SEM), Energy X-Ray diffraction (EDX), Photoelectron X-ray (XPS), Transmission electron microscope (TEM), Selected area energy diffraction (SAED) and ultraviolet visible (UV–Vis) spectroscopy. The XRD results suggested that the synthesized AA-CNC@Ag BNC material is composed of 47 % crystalline and 53 % amorphous nature having distorted hexagonal structure due to capping of Ag NPs by amorphous biopolymer matrix. The Debye-Scherer crystallite sized was calculated as 18 nm which is found in close agreement with TEM analysis (19 nm). The SAED yellow fringes simulates the miller indices values with XRD patterns and supported the surface functionalization of Ag NPs by biopolymer blend of AA-CNC. The XPS data supported the presence of Ag0 as indexed by Ag3d orbital corresponding to Ag3d3/2 at 372.6 eV and Ag3d5/2 at 366.6 eV. The surface morphological results revealed a flaky surface of the resultant material having well distributed Ag NPs in the matrix. The EDX and atomic concentration results given by XPS supported the presence if C, O and Ag in the bionanocomposite material. The UV–Vis results suggested that the material is both UV and visible light active having multiple SPR effects with anisotropy. The material was explored as a photocatalyst for remediation of wastewater contaminated by malachite green (MG) using advance oxidation process (AOP). Photocatalytic experiments were performed in order to optimize various reaction parameters such as irradiation time, pH, catalyst dose and MG concentration. The obtained results showed that almost 98.85 % of MG was degraded by using 20 mg of catalyst at pH 9 for 60 min of irradiation. The trapping experiments revealed that •O2− radicals played primary role in MG degradation. This study will provide new possible strategies for the remediation of wastewater contaminated by MG.

Magnesium ion conducting biopolymer blend-based electrolyte for energy storage application: Electrochemical characteristics

A casting technique was employed to produce plasticized magnesium ion conducting biopolymer blend electrolytes. Chitosan (CS) and polyvinyl alcohol (PVA) were used to deliver polymer blends, and 50 wt.% of magnesium nitrate (Mg(NO3)2) was incorporated as the source for Mg2+ ions supply. The CS:PVA:Mg(NO3)2 system was subjected to different concentrations of glycerol plasticizer to improve its ion conductivity. To assess their suitability as energy storage materials, the electrochemical characteristics of the fabricated films were examined employing broad methodologies. Distinguished improvement in dielectric constant was observed upon increasing plasticizer concentration. The appearance of relaxation peak in tanδ-M'' spectra and their asymmetric shape reveals the non-Debye relaxation process. The biopolymer blend electrolyte, with a plasticizer content of 55 wt.%, exhibited the highest DC conductivity, measuring 7.34 × 10−5 S.cm−1. In terms of potential stability, linear sweep voltammetry (LSV) analysis revealed a value of 2.34 V for this particular electrolyte. A non-Faradaic (capacitive) response to cyclic voltammetry (CV) is displayed, and there is no redox peak. The selected scan rate influenced the shape of the CV curves. When scan rates of 20 mV/s and 100 mV/s were employed, specific capacitance values of 5.41 and 16.46 F/g were determined. The stability of an electrochemical double-layer capacitor, which serves as an energy storage device, was evaluated by employing a charging-discharging technique and the electrode separator made of the most conducting sample. The results show promise for the potential application of the current plasticized magnesium ion-conducting biopolymer blend electrolyte in energy storage devices.

Development and Characterization of Thermoformed Bilayer Trays of Paper and Renewable Succinic Acid Derived Biopolyester Blends and Their Application to Preserve Fresh Pasta.

The present study reports on the development by thermoforming of highly sustainable trays based on a bilayer structure composed of paper substrate and a film made of a blend of partially bio-based poly(butylene succinate) (PBS) and poly(butylene succinate-co-adipate) (PBSA). The incorporation of the renewable succinic acid derived biopolyester blend film slightly improved the thermal resistance and tensile strength of paper, whereas its flexural ductility and puncture resistance were notably enhanced. Furthermore, in terms of barrier properties, the incorporation of this biopolymer blend film reduced the water and aroma vapor permeances of paper by two orders of magnitude, while it endowed the paper structure with intermediate oxygen barrier properties. The resultant thermoformed bilayer trays were, thereafter, originally applied to preserve non-thermally treated Italian artisanal fresh pasta, "fusilli calabresi" type, which was stored under refrigeration conditions for 3 weeks. Shelf-life evaluation showed that the application of the PBS-PBSA film on the paper substrate delayed color changes and mold growth for 1 week, as well as reduced drying of fresh pasta, resulting in acceptable physicochemical quality parameters within 9 days of storage. Lastly, overall migration studies performed with two food simulants demonstrated that the newly developed paper/PBS-PBSA trays are safe since these successfully comply with current legislation on plastic materials and articles intended to come into contact with food.

Effect of gamma irradiation on structural properties and rheological behavior of binary biopolymer blend: A case study on guar gum-sage seed gum blends

In this study, different gum powders (guar gum (GG), sage seed gum (SSG) and guar-sage seed gums (GG-SSG) were irradiated at 0, 5, and 10 kGy. FTIR analysis revealed some small changes in transmittance of gum samples with gamma irradiation. Flow behavior of the gum solutions (1% w/w) revealed shear thinning behavior with a n value lower than 1. The viscosity of gum solutions (1% w/w) decreased significantly with increase of irradiation dose from 0 to 10 kGy which was in consistent with the effect of irradiation dose on the consistency index (k). Herschel–Bulkley and Sisko models with higher values of determination coefficient (R2) were found to be the best models to explain the steady shear properties of non-irradiated and irradiated gum solutions. Irradiation doses (5 and 10 kGy) changed the flow behavior of guar gum solution (1%) from non-Newtonian shear-thinning to Newtonian behavior. G’ and G’’ in GG, SSG, and GG-SSG were observed to decrease in strain sweep test as the irradiation dose was increased from 0 to 10 kGy. In SSG and GG-SSG, G’ was greater than G’’ with no cross over in all the applied frequency range, while guar gum exhibited a solid-like behavior after cross over point. Frequency sweep rheological parameters of gum solutions (1%) including G’, G’’, and (η*) also affected by gamma irradiation and decreased significantly with increasing irradiation dose from 0 to 10 kGy (p<0.05).

Formation of silver particles in [PVA:CS:PEG]-AgNO3 based biopolymer electrolyte membranes: Structural and electric transport properties study

[Chitosan (CS)-poly(vinyl) alcohol (PVA)-polyethylene glycol (PEG-200)]+xwt% silver nitrate (AgNO3) (x = 0, 10, 20, 30, 40) based biopolymer blend electrolytes (BPBEs) were prepared using solution casting method. FTIR results show the interaction of Ag+/NO3− with the constituents of polymers CS/PVA. XRD results reveal that the amorphousness increases with increasing AgNO3 concentration. Optical morphological (OM) images show that the silver, Ag(o) particles are agglomerated on the surface of the membrane. Temperature dependent dc conductivity (σdc) and dielectric relaxation frequency (fr) for BPBEs follow the Arrhenius type behavior and the sample containing 30 wt% salt has optimum dc conductivity, σdc∼1.7×10−4 S/cm at 30oC with lowest activation energy∼ 0.16 eV. The ac conductivity spectra follow the Jonscher's power law (JPL) with power law exponent, s > 1. The scaling of AC conductivity and loss tangent (tanδ) spectra were performed with respect to temperatures/concentrations of salt. The dielectric permittivity study reveals that the electrode polarization effect predominates at low frequencies. The Ionic Transference Number (ITN) measurement was used to determine the nature species of charge carrier, either ionic or electronic. The linear sweep voltammetry (LSV), result shows that 30% AgNO3containing sample has the electrochemical stability window (ESW) ∼+1.5 to -1.5 V.

Effect of food simulants on stability of copper oxide in bionanocomposite food packaging film

AbstractAddition of copper oxide nanoparticles (CuONPs) to poly (butylene‐adipate‐co‐terephthalate) (PBAT)/thermoplastic starch (TPS) biopolymer blend produced bionanocomposite films with improved mechanical and oxygen barrier properties, as well as enhanced other benefits including antimicrobial activity. In this study, the PBAT/TPS‐CuO bionanocomposite films with varying CuONPs contents (0.05%, 0.5%, 1%, and 2%) were challenged by food simulants (10% ethanol represented to aqueous food and 3% acetic acid represented to acidic food) in accordance with European Regulation 10/2011. CuONPs in the bionanocomposite films demonstrated good stability when exposed to 10% ethanol; however, it was dissolved in 3% acetic acid. The X‐ray diffraction and the energy dispersive spectroscopy results showed that CuONPs in the film were completely lost after acid exposure, whereas CuONPs in the films exposed to 10% EtOH were preserved. The maximum overall migration value was 5.0 mg/dm2. Inductively coupled plasma optical emission spectroscopy was used to confirm the presence of Cu in the simulants. The highest soluble Cu value of 12.39 mg/kg was detected from PBAT/TPS‐CuO2%, while migration value decreased as concentration ratio in film decreased. Although both values were within the threshold limits established by current legislation for non‐specific migration limit substances in food contact materials, the properties of bionanocomposite were altered. The mechanical properties of a post‐migrated PBAT‐TPS/CuO films taken from acidic conditions were reduced by 22% in tensile strength and 53% in elongation at break due to holes and microcracks on the film surface observed by scanning electron microscope. The average sealing strength of all bionanocomposite films decreased by about 25% after acid exposure. The oxygen permeability, on the other hand, was significantly improved, with a 16.3% reduction. Because the film had lost all of its active agent, film was unable to inhibit Escherichia coli growth. While 3% acetic acid caused dissolution of CuONPs and significant changes in properties of PBAT/TPS‐CuO film, 10% ethanol caused very minor to no changes in bionanocomposite film properties.

Optimization of Chitosan: Methylcellulose polyblend to obtain highly amorphous polymer matrix useful for ion transportation

Solid biopolymer blend systems consisting of chitosan (CH) and methylcellulose (MC) have been prepared in various compositions through the solution casting method and are characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The XRD data revealed that the blend composed of 30 wt.% of MC is found to be more amorphous. Structural analysis and the extent of interaction between the two polymers, i.e., CH and MC were concluded through FTIR analysis. The dielectric results also show that the blend composed of 70 wt.% of CH shows the highest value of the dielectric constant. The blend system consisting of 70 wt.% of CH and 30 wt.% of MC exhibited good thermal stability and the lowest glass transition temperature ({T}_{g}).Graphical

Enhanced properties of PBAT/TPS biopolymer blend with CuO nanoparticles for promising active packaging

Blending poly(butylene adipate-co-terephthalate) (PBAT) with thermoplastic starch (TPS) has been extensively investigated for cost reduction and better biodegradability. However, film blend showed poor thermal, mechanical and barrier properties. The feasibility of incorporating copper oxide nanoparticles (CuONPs) at concentrations ranging from 0.05% to 2% to reinforce PBAT/TPS (70:30) films was studied. Melt flow index of the blend increased from 3.52 to 7.24 g/10 min as the CuONPs concentration increased, resulting in a decrease in torque during the blown-film extrusion. Scanning electron microscopy with energy-dispersive X-ray analysis and X-ray diffraction indicated that CuONPs were located in the TPS phase without modification of the crystalline structure. CuONP addition improved the thermal stability of PBAT/TPS by shifting the degradation temperature at T10% to a higher zone. During heat sealing, high conductivity of Cu promoted interfacial interactions across the film surfaces, resulting in stronger sealing. At 2% CuONPs, tensile strength increased by 29.1%, while Young’s modulus increased by 9.3% compared to PBAT/TPS. The hydrophilicity of TPS significantly reduced oxygen permeability of pristine PBAT by 28.7%, while low CuONP concentrations promoted the gas diffusion rate. Higher CuONP concentrations created more tortuous paths, increasing the oxygen barrier of the bionanocomposites to PBAT/TPS levels. Inclusion of CuONPs also improved the water vapor barrier property of PBAT/TPS films. The bionanocomposite film showed effective antibacterial activity against Escherichia coli (99.7% reduction). These findings suggest that the PBAT/TPS-CuO bionanocomposite film can be feasibly produced and used in food packaging to preserve the food quality and extend the shelf-life of product.

Electrospun Materials Based on Polymer and Biopolymer Blends-A Review.

This review covers recent developments and progress in polymer and biopolymer blending and material preparation by electrospinning. Electrospinning is a technique that is used to produce nanofibers to improve the quality of membranes. Electrospun nanofibers are highly applicable in biomedical sciences, supercapacitors, and in water treatment following metal ion adsorption. The key affecting factors of electrospinning have been checked in the literature to obtain optimal conditions of the electrospinning process. Future research directions and outlooks have been suggested to think about innovative ideas for research in this field.

Investigation on the structural and ion transport properties of magnesium salt doped HPMC-PVA based polymer blend for energy storage applications

The effects of Mg (NO3)2. 6H2O salt on an eco-friendly biopolymer blend matrix comprising hydroxypropyl methylcellulose (HPMC) and poly (vinyl alcohol) (PVA) is presented in this work which is prepared using the solution casting method. Structural, chemical composition (functional moieties), morphological, and thermal features were investigated by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FE-SEM), Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). FTIR spectrum and XRD pattern confirmed that the magnesium nitrate salt was dissolved, and complexation was observed through a coordination bond and a hydrogen bond with -OH and -CH groups in the host polymer blend. The glass transition temperature (Tg) values of HPMC:PVA composites are greater than those of the pure blend, demonstrating transient cross-linking. For P0, P2, and P3 samples, the pore diameter and % porosity is calculated, and the morphology of the P4 sample is non-porous and shows ionic conductivity of P4 = 3.25 × 10−4 S/cm at 27 °C. Based on the Nyquist plot fitting and FTIR deconvolution methods, it is used to determine the transport characteristics and noticed that the carrier concentration affects the ionic conductivity. The highest conducting electrolyte has been integrated into a primary battery to demonstrate its potential use in energy storage systems.

Effects of primary, secondary and tertiary structures on functional properties of thermoplastic starch biopolymer blend films

To better understand the correlation between structure and properties in thermoplastic starch biopolymer blend films, the effects of amylose content, chain length distribution of amylopectin and molecular orientation of thermoplastic sweet potato starch (TSPS) and thermoplastic pea starch (TPES) on microstructure and functional properties of thermoplastic starch biopolymer blend films were studied. After thermoplastic extrusion, the amylose contents of TSPS and TPES decreased by 16.10 % and 13.13 %, respectively. The proportion of the chains with the degree of polymerization between 9 and 24 of amylopectin in TSPS and TPES increased from 67.61 % to 69.50 %, and from 69.51 % to 71.06 %, respectively. As a result, the degree of crystallinity and molecular orientation of TSPS and TPES films increased as compared to sweet potato starch and pea starch films. The thermoplastic starch biopolymer blend films possessed a more homogeneous and compacter network. The tensile strength and water resistance of thermoplastic starch biopolymer blend films increased significantly, whereas thickness and elongation at break of thermoplastic starch biopolymer blend films decreased significantly.

Full factorial design of experiment-based and response surface methodology approach for evaluating variation in uniaxial compressive mechanical properties, and biocompatibility of photocurable PEGDMA-based scaffolds

The goal of this study is to fabricate biocompatible and minimally invasive bone tissue engineering scaffolds that allow in situ photocuring and further investigate the effect on the mechanical properties of the scaffold due to the prevailing conditions around defect sites, such as the shift in pH from the physiological environment and swelling due to accumulation of fluids during inflammation. A novel approach of incorporating a general full factorial design of experiment (DOE) model to study the effect of the local environment of the tissue defect on the mechanical properties of these injectable and photocurable scaffolds has been formulated. Moreover, the cross-interaction between factors, such as pH and immersion time, was studied as an effect on the response variable. This study encompasses the fabrication and uniaxial mechanical testing of polyethylene glycol dimethacrylate (PEGDMA) scaffolds for injectable tissue engineering applications, along with the loss in weight of the scaffolds over 72 h in a varying pH environment that mimics in vivo conditions around a defect. The DOE model was constructed with three factors: the combination of PEGDMA and nano-hydroxyapatite referred to as biopolymer blend, the pH of the buffer solution used for immersing the scaffolds, and the immersion time of the scaffolds in the buffer solution. The response variables recorded were compressive modulus, compressive strength, and the weight loss of the scaffolds over 72 h of immersion in phosphate-buffered saline at respective pH. The statistical model analysis provided adequate information in explaining a strong interaction of the factors on the response variables. Further, it revealed a significant cross-interaction between the factors. The factors such as the biopolymer blend and pH of the buffer solution significantly affected the response variables, compressive modulus and strength. At the same time, the immersion time had a strong effect on the loss in weight from the scaffolds over 72 h of soaking in the buffer solution. The biocompatibility study done using a set of fluorescent dyes for these tissue scaffolds highlighted an enhancement in the pre-osteoblasts (OB-6) cell attachment over time up to day 14. The representative fluorescent images revealed an increase in cell attachment activity over time. This study has opened a new horizon in optimizing the factors represented in the DOE model for tunable PEGDMA-based injectable scaffold systems with enhanced bioactivity.

Plasticization effect of ionic liquid on structural, thermal and ion transport properties of CS-PVA-NaI based bio-polymer electrolyte membranes

ABSTRACT Plasticized bio-polymer blend electrolytes (BPBEs) based on CS-PVA-NaI-xwt% ionic liquid (IL), 1-ethyl-3-methylimidazolium methyl sulfate [EMIM][MS] were prepared using solution cast method. The prepared samples have been characterized using FTIR (in ATR mode), XRD, TGA, Impedance spectroscopy, ITN, LSV, and CV measurement. XRD result shows the semi-crystalline nature of BPEs films with characteristic peaks centered at 2θ = 21°. The % degree of crystallinity (Xc) for BPBE films were found to decrease up to 15 wt%IL. FTIR analysis shows the interaction of NaI/IL with the constituents of polymer CS/PVA. Thermo-gravimetric analysis (TGA) shows that the BPBE film has multistep decomposition. AC conductivity spectra follow the Joncher’s power law (JPL) with the value of power law exponent >1. The transportation of charge carriers in the BPBE films follows the cage type correlate barrier hoping (CBH) mechanism. The sample, BPBE#15IL, was found to be optimum dc conductivity ~ 1.7x10−4S/cm at 30℃. The electrode polarization and conductivity relaxation in terms of dielectric permittivity and electric modulus have been realized. Ionic transference number (ITN) measurement reveals that the sample BPBE#15IL has the ionic conductivity due to ions only (ITN~ 0.99). LSV measurement shows that the value of electrochemical stability window (ESW) for sample BPBE#15IL ~±2.3 V. CV plot shows the appearance of symmetric oxidation-reduction peaks appeared at ~±1.5 V.

CuO Nanorods Immobilized Agar-Alginate Biopolymer: A Green Functional Material for Photocatalytic Degradation of Amaranth Dye.

The contamination of water is increasing day by day due to the increase of urbanization and population. Textile industries contribute to this by discarding their waste directly into water streams without proper treatment. A recent study explores the treatment potential of copper oxide nanorods (CuO NRs) synthesized on a green basis in the presence of a biopolymer matrix of agar (AA) and alginate (Alg), in terms of cost effectiveness and environmental impact. The synthesized bio nanocomposite (BNC) was characterized by using different instrumental techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), ultra-violet spectroscopy (UV-Vis), scanning electron microscopy-energy dispersive X-ray-elemental analysis (SEM-EDX), transmission electron microscopy (TEM), selected area diffraction pattern (SAED) and X-ray photoelectron spectroscopy (XPS). The optical studies revealed that immobilization of CuO NRs with Alg-Agar biopolymer blend resulted in an increase in light absorption capacity by decreasing the energy bandgap from 2.53 eV to 2.37 eV. The bio nanocomposite was utilized as a photocatalyst for the degradation of amaranth (AN) dye from an aquatic environment under visible light irradiation. A statistical tool known as central composite design (CCD) associated with response surface methodology (RSM) was taken into consideration to evaluate the optimized values of process variables and their synergistic effect on photocatalytic efficiency. The optimized values of process variables were found to be irradiation time (45 min), AN concentration (80 ppm), catalyst dose (20 mg), and pH (4), resulting in 95.69% of dye degradation at 95% confidence level with desirability level 1. The rate of AN degradation was best defined by pseudo-first-order reaction based on the correlation coefficient value (R2 = 0.99) suggesting the establishment of adsorption-desorption equilibrium initially at the catalyst surface then photogenerated •O2- radicals interacting with AN molecule to mineralize them into small non-toxic entities like CO2, H2O. The material used has high efficiency and stability in photocatalytic degradation experiments up to four cycles of reusability.

Tailoring the performance of boehmite nanoparticles reinforced carboxymethyl chitosan/cashew gum blend nanocomposites via green synthesis

The main motivation for this study stemmed from the demand for bio-friendly polymeric materials with enhanced properties in various fields of application. Biopolymer blend nanocomposite films based on carboxymethyl chitosan (CMCS) and cashew gum (CG) with different contents of boehmite nanoparticles were prepared via a purely green method using water as the solvent. The successful inclusion of boehmite nanoparticles in the CMCS/CG blend was verified by Fourier transform infrared (FTIR) analysis. Scanning electron microscopy (SEM) and optical microscopy were used to analyze the surface microstructure of prepared films. SEM and optical images revealed a uniform distribution of nanofillers in the blend because of the strong interactions between nanoparticles and the CMCS/CG blend segments. The thermogravimetric analysis demonstrates that the addition of boehmite nanoparticles increased the thermal stability of the biopolymer blend films. Differential scanning calorimetry (DSC) showed a small shift in the glass transition and melting temperature of pristine blend to higher values with the addition of boehmite. The correlation of AC conductivity with varying frequency and temperature was evaluated. The maximum conductivity was shown by CMCS/CG blend with 7 wt % boehmite, which was further supported by their lowest activation energy value. Nyquist plots were used to illustrate the complex impedance of prepared nanocomposite films. A decrease in the area under the semicircular arc with temperature suggested an increase in conductivity with temperature. The dielectric constant and dielectric loss factor of blend and its nanocomposite films were found to increase with temperature. Boehmite addition increased tensile strength and hardness while lowering elongation at break up to a specific concentration. The synthesized CMCS/CG/boehmite films can be used as environmentally friendly alternatives in the development of flexible organic electronics and charge harvesting devices.

Effect of ionic liquid on plasticized CS-PVP-NaI based bio-polymer blend electrolytes: Structural, thermal, dielectric and ion transport properties study

The effect of imidazolium based ionic liquid (IL), 1-ethyl-3-methylimidazolium methyl sulfate [EMIM][MeSO4] on structural, thermal, dielectric and ion transport properties of Chitosan (CS)-poly(vinyl) pyrrolidone (PVP)-polyethylene glycol (PEG)-sodium iodide (NaI) based bio-polymer blend electrolyte (BPBE) films were studied using XRD, SEM, optical microscopy (OM), ATR-FTIR, TGA and impedance spectroscopic techniques. The BPBE films based on CS-PVP-PEG-NaI-IL (x = 0, 10, 20, 30, 40, 50, 60) have been prepared using solution cast method. The sample 50IL has been found to have maximum ionic conductivity ∼ 6.10 × 10-4 S/cm at 30 °C. The XRD results reveal that the BPBE films are semi-crystalline in nature and amorphousness is optimum for 50IL. ATR-FTIR analysis reveals the interaction between the functional groups of bio-polymer electrolyte with the cations/anions of IL/salt. TGA analysis shows that the BPBE films were decomposed in multi steps. Optical microscopy results show the reduction in surface roughness with increasing IL content. This result also confirmed by SEM analysis. LSV and CV measurements were carried out for knowing the electrochemical stability window (ESW). Ionic transference number (ITN) measurement shows the 50IL sample has ITN ∼ 0.98.

Study of Morphology, Rheology, and Dynamic Properties toward Unveiling the Partial Miscibility in Poly(lactic acid)-Poly(hydroxybutyrate-co-hydroxyvalerate) Blends.

The purpose of the present work was to gain a fundamental understanding of how the composition and physico-chemical properties affect the rheology, morphology, miscibility, and thermal stability of poly(lactic acid) (PLA)-poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) biopolymer blends obtained by melt mixing. First, restricted processing conditions were chosen, due to the inherent thermal degradation of PHBV, as proven by rheological dynamic time sweep (DTS) measurements and size-exclusion chromatography (SEC). Based on this, the composition dependence of the blends was investigated using small-amplitude oscillatory shear rheology (SAOS), and the results were confirmed by scanning electron microscopy (SEM) analysis. Subsequently, the changes in glass transition temperatures (Tgs) from the molten to the solid state, as observed by DMA and DSC, were verified by coupling SAOS to dielectric relaxation spectroscopy (DRS). Herein, the thermo-rheological complexity of PLA/PHBV blends in the melt was revealed, especially for PLA-rich blends. Irregularly structured morphologies, caused by highly mismatched viscoelastic properties, illustrated the degree of partial miscibility. Moreover, the thermo-rheological complexity appeared in the molten state of the asymmetric PLA-rich phases could be correlated to the crystal-amorphous interfacial MWS polarization, because of the locally-induced phase separation and heterogeneity, and owing to the differences in their crystallization properties during cooling. The miscibility also suffered from the lower thermal stability of PLA and the even more unstable PHBV. Nevertheless, the melt-induced degradation process of the PLA/PHBV blends seemed to be responsible for some of the in situ self-compatibilization and plasticization mechanisms. As a result, the miscibility and thermo-rheological simplicity were improved for the intermediate and PHBV-rich compositions at low temperatures, since their properties were, to a large extent, governed by the significant degradation of PHBV. The present findings should increase the understanding of morphological changes in PLA/PHBV blends and help control their micro/nanostructure.