Synthesis of a starch–acrylic acid–chitosan copolymer as flocculant for dye removal

Flocculants prepared with modified natural polymers have recently attracted extensive attention in the field of water treatment. In this work, acrylic acid was successfully grafted onto the backbones of starch and chitosan by free radical polymerization. The synthesis parameters of initiator concentration, reaction temperature, and neutralization degree of acrylic acid were optimized as 0.4 wt %, 50 °C, and 70%, respectively, according to the flocculation performance. The ternary copolymer starch–acrylic acid–chitosan (SAAC) could completely remove Acid Blue 113 from 100 mg/L of simulated wastewater (color removal efficiency 99.7%) at the flocculant dosage of 100 mg/L. The SAAC also had effective flocculation capability in a wide range of flocculant dosages and pH values of wastewater. The ternary copolymer based on two natural polymers has enormous potential as flocculant with its advantages of low price, ecofriendliness, and high performance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47437.     

Biodegradable porous polylactic acid film as a separator for supercapacitors

A porous polylactic acid (PLA) film was investigated as a separator for supercapacitors (SCs) and compared with commercial separators, for example, NKK-MPF30AC and Celgard 2400. The porous PLA film was fabricated via a facile phase inversion method, and the cross-sectional scanning electron microscope images of the PLA separator film exhibited highly porous interconnected morphology for ion diffusion. The surface modification of separators was performed by radio frequency (RF) air plasma to improve wettability. The plasma modification enhanced the water uptake and swelling properties of the separators and decreased the water contact angles of PLA and Celgard 2400 films. The mechanical and dielectric properties of separators were also studied. The ionic conductivities of RF-PLA in 1 M H₂SO₄ and 1 M Na₂SO₄ were found to be 1.1 × 10⁻¹ S/cm and 0.6 × 10⁻² S/cm at room temperature, respectively. The electrochemical impedance spectroscopy of the RF-PLA SCs showed the lowest solution resistance and internal resistance.     

Phenol removal from wastewater using eco-friendly hybrid hydrogels

The intent of this study was to evaluate the ability of low-cost polyacrylamide/starch hybrid hydrogels in removing organic pollutants from wastewater, using phenol as a model compound, besides of investigating the adsorption/desorption behavior as a function of hydrogels composition. The results indicated that the hydrogel with the lowest amount of starch and crosslinking agent exhibited the maximum phenol adsorption capacity, 21 mg g⁻¹. The adsorption isotherm data were described by Langmuir and Freundlich adsorption isotherm models. According to linear regression analysis, the Freundlich isotherm model was the best fit among the isotherm models for the adsorption process. Furthermore, desorption study revealed a minimum of about 60% of phenol release, indicating reusability to wastewater treatment.     

The synthesis of modified alginate flocculants and their properties for removing heavy metal ions of wastewater

A new flocculant was synthesized through the modification of sodium alginate with thiosemicarbazide. In the preparation, amino thiourea groups which had excellent adsorption properties for heavy metal ions were introduced to the flocculant. The structure of the flocculant was confirmed by elemental analysis, Fourier transform infrared, UV spectrophotometry, nuclear magnetic resonance, and thermal analysis. The flocculation behaviors of the flocculant for three heavy metal ions were investigated. The results showed that the removal rates of the flocculant for Pb²⁺, Cd²⁺, and Cu²⁺ reached up to 97.8%, 86.3%, and 80.0%, respectively, and the flocculation capacities were as high as 489, 215, and 160 mg/g, respectively. The excellent adsorption was ascribed to the double effects of electronic interaction and chelation between the flocculant and heavy metal ions. The flocculant had particular flocculation selectivity for Pb²⁺ in the mixed heavy metal ion solutions containing Cd²⁺or Cu²⁺, respectively. The flocculation process corresponded to Langmuir isotherm model, the flocculation kinetics agree with pseudo second order. The flocculant had potential applications for treatment of wastewater. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46577.     

Effect of urea and formamide plasticizers on starch/PVA bioblend sheets

The starch/polyvinyl alcohol (PVA) bioblend sheets containing urea and formamide as plasticizers were prepared through melt processing in presence of water. The experiments indicated that urea and formamide plasticizers could form strong hydrogen bonds with starch/PVA molecules. Urea exhibited better plasticizing effect than formamide. Urea also could greatly destroy the crystal structures of PVA component in the blends, leading to the decreased crystallinity of the blends. Formamide was a good solvent for urea and could prevent urea separating from the blends, resulting in the improved stability of plasticizing systems. The blends exhibited good flexibility. Therefore, the incorporation of both urea and formamide into starch/PVA blends could exhibit synergistic effects to ensure the blends with both good plasticizing effect and the stability of the plasticizing systems. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42311.     

Utilization of ramon seeds (Brosimum alicastrum swarts) as a new source material for thermoplastic starch production

The development and characterization of biodegradable polymers deriving from renewable natural sources has attracted much attention. The aim of this work was to partially characterize a thermoplastic starch obtained from the starch of seeds from the ramon tree (TPS‐RS) as an option to substitute thermoplastic starch from corn (TPS‐CS), in some of its applications. At 55% of relative humidity (RH), TPS‐RS had higher tensile strength and deformation than TPS‐CS. X‐ray diffraction analysis showed similar values in residual crystallinity (percentage of crystallinity that remains after plasticization process) in both TPS. The SEM micrographs showed a few remnant granular structures in the TPS‐RS. The FTIR showed a greater intensity in band at 1016 cm^?1 in the TPS‐CS and TPS‐RS in comparison with their corresponding native starch, indicating an increase in the amorphous region after plasticization. The TGA analysis showed greater thermal stability in TPS‐CS (340 °C) compared with TPS‐RS (327 °C). In addition, the glass transition temperature in both TPS was 24 °C. The results obtained represent a starting point to potentialize the use of TPS‐RS instead of TPS‐CS for the development of new biodegradable materials for practical applications in different areas. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44235.     

Poly(lactic acid)/starch composites: Effect of microstructure and morphology of starch granules on performance

Starches used to develop biodegradable composites belong to different botanical sources that exhibit different microstructures and morphologies. This results in confused relationship and no comparison of data for applications. In this work, the most popular ten different starches were used as model materials to investigate the relationship between starch microstructure and the performance of poly(lactic acid) (PLA)/starch composites. It was found that: (a) composites filled with either well‐sized (small‐sized and non‐agglomerated) starch granules or those containing high amylose content (G‐50 and G‐80) improves the reinforcing ability of PLA, with least reduction in deformation; (b) aggregation tendency of small‐sized starch granules can be controlled using surface modification approach that not only reduces the phase‐separation between starch and PLA but also improves the dispersion; and (c) no discernible relationship exists between the starches, from different botanical sources, and the thermal performance of PLA/starch composites. The results provide practical guidelines to develop starch‐based biodegradable composites for commercial applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45504.     

Biopolymer blended films of poly(butylene succinate)/cyclic olefin copolymer with enhanced mechanical strength for packaging applications

The demand for biodegradable materials is on the rise because humanity is now more concerned about a sustainable lifestyle than ever before. In this regard, we present solution casting synthesized novel biopolymer blended films of poly(butylene succinate)/cyclic olefin copolymer (PBS/COC) for packaging applications. These films were characterized by X-ray diffraction (XRD), Fourier transform infrared microscopy (FTIR), scanning electron microscopy (SEM), universal tensile testing (ASTM D882 standard), and antibacterial Disc diffusion tests using gram-negative Escherichia coli (E.coli) and gram-positive Staphylococcus aureus (S.aureus) bacteria. The XRD and FTIR revealed the type of bonding to be physical in-between the constituent polymers; ensuring the biodegradable nature of their blends, while the thickness of films was found to be <100 μm. The SEM, tensile, and antibacterial testing concluded that 30%PBS with 70%COC by weight blending is the best composition; showing a compact/pin-holes free morphology, the highest strength of 91 MPa, and contact inhibition with E.coli and S.aureus bacteria.     

Polyurethane‐functionalized starch nanoparticles for the purification of biodiesel

Polyurethane‐functionalized starch nanoparticles (PUFSNPs) have been synthesized by chemical modification of polyhydroxylated starch nanocrystals (SNC) with aliphatic and aromatic diisocyanates. The covalent attachment of the diisocyanates to the backbone of SNC for the formation of starch‐derived nanopolyurethane polymers was unambiguously determined by FTIR and NMR spectroscopy. PUFSNPs were entirely obtained from SNC with yields ranging from 41.5 to 86.0 wt % and their size distribution, size, porosity and morphology were determined by dynamic light scattering (DLS), high resolution transmission electron microscopy (HRTEM) and Brunauer–Emmett–Teller (BET) adsorption techniques. The size and surface area of the cyclic aliphatic‐based PUFSNP (NPU4) is 27 nm and 52.64 m² g^?1, respectively, indicating one of the potential and promising biodegradable materials for the adsorption of acid impurities and contaminants that are found in crude biodiesel. The acid content of the biodiesel is remarkably reduced by 32–39% with PUFSNPs while 7–18% with their corresponding bulk materials. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44463.     

Functionalized chitosan with butylammonium ionic liquids for removal of Cr(VI) from aqueous solution

Environmental pollution by heavy metals is currently a problem of great concern for human health. In this context, this study aims to contribute with the synthesis and characterization of chitosan functionalized with three different ionic liquids (n-butylammonium acetate, sec-butylammonium acetate, and tert-butylammonium acetate) followed by its application in hexavalent chromium effluent treatment. The adsorbents synthesized (ChN, ChS, and ChT) were characterized by SEM, EDS, FTIR, BET, RDD, PSD, and XRD techniques. Afterward, the influences of temperature, contact time, and pH on the Cr(VI) adsorption process were evaluated. The solution with pH 3 displayed the highest adsorption capacities (107.31, 104.60, and 107.97 mg.g^-1 for ChN, ChS, and ChT, respectively). The kinetic data were better adjusted to the Weber-Morris kinetic model with an ideal time of 2 h. Furthermore, the influence of temperature was evaluated using the Freundlich and Langmuir isotherms, with maximum capacities of 142.05 (ChN), 131.58 (ChS), and 146.63 mg.g^-1 (ChT). The adsorbent displayed enhanced adsorption properties in comparison with raw chitosan by an intensification of the electrostatic interaction between amino groups and hexavalent chromium. Finally, the reusability was investigated, and significant results were observed (84.33 ± 4.87%) in the adsorption process after 4 cycles.     

Synthesis and characterization of PMMA composites activated with starch for immobilization of L‐asparaginase

Poly (methyl methacrylate) (PMMA)–starch composites were prepared by emulsion polymerization technique for L‐asparaginase (L‐ASNase) immobilization as highly activated support. The hydroxide groups on the prepared composites offer a very simple, mild and firm combination for enzyme immobilization. The pure PMMA and PMMA‐starch composites were characterized as structural, thermal and morphological. PMMA‐starch composites were found to have better thermal stability and more hydrophilic character than pure PMMA. L‐ASNase was immobilized onto PMMA‐starch composites contained the different ratio of starch (1, 3, 5, and 10 wt %). Immobilized L‐ASNase showed better performance as compared to the native enzyme in terms of thermal stability and pH. K_m value of immobilized enzyme decreased approximately eightfold compared with the native enzyme. In addition to, immobilized L‐ASNase was found to retain 60% of activity after 1‐month storage period at 4 °C. Therefore, PMMA‐starch composites can be provided more advantageous in terms of enzymatic affinity, thermal, pH and storage stability as L‐ASNase immobilization matrix. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43421.     

Ultra‐microstructural features of perborate oxidized starch

Ultrafine structures of low, medium, and highly oxidized starches, symbolized as LOS, MOS, and HOS, respectively, were thoroughly investigated. These oxidized starches were obtained by treatment of native starch (NS) with three different concentrations of sodium perborate (SPB). Thus, obtained products were studied with respect to major chemical and fine physical characteristics vis‐a‐vis these of NS (a) acidic and reduced groups creation along with mode of association, (b) significant increase in solubility, and (c) outstanding decrease in apparent viscosity. Thermogravimetric analysis (TGA) revealed thermal stability of the said substrates follows order: HOS > MOS > LOS > NS. Scanning electron micrographs (SEM) showed polygonal or irregular shape with particle size ranging from 2 to 20 μ. After oxidation, the starch surface became rough and the edges lost their definiteness completely. In conclusion, SPB is an efficient oxidant to produce oxidized starches with useful characteristics, which advocate them to wide applications in textile sizing and medicinal domains. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40170.     

Water‐compatible imprinted polymers based on CS@SiO2 particles for selective recognition of naringin

Molecularly imprinted polymers are being proposed for the development of novel biorecognition elements for active components. In this study, an imprinted chitosan coated silica nanoparticles (I‐CS@SiO₂) polymer was prepared by a simple procedure, in which, naringin (NG) with antioxidant activity, acted as a template, silica as a matrix and CS as a functional polymer. The binding properties were discussed by the equilibrium binding experiment method. Experiments show that the adsorption characteristics of I‐CS@SiO₂ are better than that of nonimprinted polymer. It exhibited high selectivity for NG when compared with the nonimprinted polymer, with an imprinting factor α of 1.74. Scatchard analysis of the I‐CS@SiO₂ indicated that there was a class of binding sites during the I‐CS@SiO₂ recognizing NG: The dissociation constant of K_D is 0.016 mmol L^?1, the maximum apparent binding capacity of B_max is 6.56 μmol g^?1. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40491.     

Improvement of antifouling performance of poly(l‐lactic acid) membranes through incorporating polyaniline nanoparticles

Poly(l ‐lactic acid) (PLLA) composite membranes were fabricated by nonsolvent induced phase separation method using polyaniline (PANI) as an additive. Membrane structure was characterized by attenuated total reflectance Fourier transform‐infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, porosity, and pore size analysis. Membrane performance was assessed by goniometer, pure water flux, molecular weight cut‐off, static adsorption and dynamic filtration. The incorporation of PANI significantly improved the hydrophilicity and permeability of PLLA composite membrane, and eventually enhanced the antifouling performance of composite membrane compared with pure PLLA membrane. It was demonstrated that PLLA composite membrane with 1 wt % PANI had better separation and antifouling performance compared with other composite membranes. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44452.     

Preparation of cationic modified collagen extracted from leather wastes and their application in dye flocculation

A series of novel cationic flocculants are designed and synthesized successfully by grafting two monomers onto the collagen backbone, namely acrylamide (AM) and 2‐methacryloyloxyethyltrimethyl ammonium chloride (DMC). Apparently, these effective grafting modifications are well demonstrated by adopting FTIR and H¹ NMR measurements, which could be used to estimate grafting ratios of corresponding monomers approximately. Additionally, significant improvements in positive charge densities and amorphous aggregation structures are also definitely confirmed by Zeta and XRD measurements, respectively. Moreover, thermogravimetric analysis clearly proves the formation of cationic branched chain architectures, whose maximum thermal degradation temperature would significantly decrease with the introduction of AM. In addition, much more porous and rougher surface structures could be visibly observed after successful grafting modifications. Furthermore, when the feeding weight ratio between collagen and DMC is controlled at 1:3, or the equal amounts of AM and DMC are introduced meanwhile the mass ratio between collagen and mixed monomers (DMC + AM) is fixed at 1:4, the samples acquired could both perform the best in decolorizing the model wastewater containing methyl orange (MO) dyes in their groups, and hereby, a corresponding flocculation mechanism is also proposed based on the structural analysis of the formed flocs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45363.     

Polyhydroxyalkanoate coatings restrict moisture uptake and associated loss of barrier properties of thermoplastic starch films

This work investigates the use of polyhydroxyalkanoate (PHA) films as moisture barriers for thermoplastic starch (TPS) films, to produce biodegradable, multi‐layer materials with high gas barrier properties. This is a necessary extension to the limited work available on this topic and confirms that PHAs are suitable coating materials for TPS films intended for use in food packaging. Under storage conditions of up to 75% relative humidity (RH) for 2 weeks, a PHA coating maintained the moisture content (MC) of the TPS below the point at which its barrier properties were detrimentally affected. Furthermore, for PHBV coating thicknesses of 91–115 μm, the MC of the TPS remains significantly lower than uncoated TPS for the duration of the experiment (>25 days). The flux of water into the coated TPS fit to a model based on Fick's law. However, when the multi‐layered films were stored at 95% RH delamination occurred within 24 h. Preliminary investigation into possible material design improvements showed that the addition of a small amount of PHA to the TPS layer prolonged the time to delamination. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46379.     

Effects of sorbitol and formamide plasticizers on molecular motion in corn starch studied using NMR and DMTA

Mechanical and thermal properties of composite polymer materials strongly depend on their local structure and molecular dynamics which can be effectively studied by the solid-state nuclear magnetic resonance (NMR) techniques. In the present paper, the influence of formamide (F) and sorbitol (S) plasticizers on molecular motion in thermoplastic starch (TPS) was studied using solid-state NMR spectroscopy and dynamic mechanical thermal analysis (DMTA). DMTA measurements carried out for formamide- (F-TPS) and sorbitol-plasticized (S-TPS) corn starches indicated heterogeneous plasticizer distribution of plasticizer-rich and starch-rich phases within the samples. The single pulse and cross-polarization ¹³C NMR spectra measured for both plasticized starches confirmed the amorphous character of their structure and distinctly different chain mobility supported by the values of ¹³C spin–lattice relaxation times. The results of the analysis of broad line and magic angle spinning ¹H NMR spectra are in accordance with the results of DMTA measurements, revealing lower mobility of starch chains within S-TPS in comparison to F-TPS. Crosslinking of the starch chains with sorbitol molecules was suggested as being responsible for the lower mobility of the starch chains in S-TPS. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48964.     

Fully bio‐based polyesters derived from 2,5‐furandicarboxylic acid (2,5‐FDCA) and dodecanedioic acid (DDCA): From semicrystalline thermoplastic to amorphous elastomer

A serials of fully bio‐based poly(ethylene dodecanedioate‐2,5‐furandicarboxylate) (PEDF) were synthesized from Dodecanedioic acid (DDCA), 2,5‐Furandicarboxylic acid (2,5‐FDCA), and ethylene glycol through a two‐step procedure consisted of transesterification and polycondensation. After their chemical structures were confirmed by Nuclear Magnetic Resonance and Fourier Transform Infrared Spectroscopy, their thermal, mechanical, and biodegradation properties were investigated in detail. Results showed that the chemical composition of PEDFs could be easily controlled by the feeding mole ratio of DDCA to FDCA and they possessed the characteristic of random copolyester with the intrinsic viscosity ranged from 0.82 to 1.2 dL/g. With the varied mole ratio of DDCA to FDCA, PEDFs could be changed from semicrystalline thermoplastic to the completely amorphous elastomer, indicated by the elongation at break ranged from 4 for poly(ethylene 2,5‐furandicarboxylate) to 1500% for amorphous PEDF‐40. The amorphous PEDF‐30 and PEDF‐40 showed satisfactory shape recovery after cyclic tensile test, which was the typical behavior for elastomer. Enzymatic degradation test indicated that all the PEDFs were biodegradable and the degradation rate was heavily affected by their chemical compositions. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46076.     

A magnetic mesoporous chitosan based core‐shells biopolymer for anionic dye adsorption: Kinetic and isothermal study and application of ANN

In this study, Chitosan/Al₂O₃/Fe₃O₄ core‐shell composite microsphere (CAMF) was used as an effective sorbent with high adsorption capacity for the removal of anionic azo dye model from aqueous solution. The obtained composite was characterized by XRD, SEM, EDX, and BET analysis. The results showed the high methyl orange (MO) adsorption in a wide pH range of 4–10 and the optimum adsorbent dosage was obtained 0.6 g L^?1. It is indicated that the equilibrium data followed the Langmuir isotherm model and the adsorption kinetic was well fitted with pseudo‐second‐order kinetic model. Also, the adsorption kinetic was controlled by the film diffusion and intra‐particle diffusion, simultaneously. It is revealed that by increasing the particle size from <0.1 μm to ～0.4 μm, the adsorption capacity did not change, significantly. The adsorption capacity of MO on CAMF was predicted by multilayer perceptron (MLP) neural network at different initial MO concentration, in which the predictions of MLP model had very good agreement with experimental data. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43466.     

Impact of the starch source on the physicochemical properties and biodegradability of different starch‐based films

Concern about environmental issues has motivated research into the development of biodegradable packaging from renewable sources. Natural polymers such as starch constitute a good alternative for diminishing the use of nonbiodegradable and nonrenewable components in the packaging industry. However, depending on the botanical source, films with different properties are formed. The aim of this study was to evaluate the film‐forming capacity of different starch sources (cassava, corn, potato, and wheat) by casting with starch contents from 2 to 6%. Principal component analysis methodology was used to evaluate the correlation between the formulations and their physicochemical and mechanical properties. It was not possible to produce continuous films based on potato starch, probably because of its very low amylose content (10%). The corn‐, cassava‐, and wheat‐starch‐based films were characterized by their thicknesses (0.06–0.22 mm), moisture contents (19–26%), water solubilities (13.7–26.5%), water‐vapor permeabilities (WVPs; 0.19–0.48 g mm h^?1 m^?2 kPa^?1), wettabilities (35–106°), biodegradabilities in soil, and thermal and mechanical properties (tensile strength = 1.9–6.7 MPa, elongation = 41–166%, and Young's modulus = 8–127 MPa). The wheat starch films presented higher WVPs and lower mechanical properties. The cassava starch films presented lower wettabilities and good mechanical properties; this suggested that their use in packaging for products, such as fruits and vegetables, with higher water activities could be feasible. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46564.