The 50 most-cited articles in Journal of Applied Polymer Science, 2017

ABSTRACT The majority of materials used for short‐term and disposable packaging application are non‐biodegradable which are not satisfying the demands in environmental safety and sustainability. Biodegradable polymers are an alternative for these non‐biodegradable materials. The biodegradable polymeric materials can degrade in a reasonable time period without causing environmental problems. However, biodegradable polymers possess some limitations such as comparatively high cost, insufficient mechanical performances, and inferior thermal stability to extend their widespread application in packaging industry. To overcome these limitations, one of the most commonly used strategies is melt blending of dissimilar biodegradable polymers. Unfortunately, most of the biodegradable polymer blends exhibit insufficient performance because they are thermodynamically immiscible as well as exhibit poor compatibility between the blended components. It has been established that the compatibilization is a well‐known strategy to improve the performances of the immiscible biodegradable polymer blends…

ABSTRACT Parts produced by extrusion‐based additive manufacturing experience the disadvantage of consisting of many weld‐lines, which consequently downgrade their mechanical properties. This work aims at maximizing the strength of printed parts by considering and improving the intra‐ and inter‐layer cohesion between adjacent strands. Therefore, printed poly(lactic acid) specimens were characterized by means of a particular tensile test setup, and the inter‐layer cohesion of printed specimens was evaluated by means of the double cantilever beam test. A detailed parametric statistical evaluation, which included printing temperatures, layer thicknesses, and layer‐designs, was complemented by the material's viscosity data and the analysis of the specimens' fracture surfaces and cross‐sections. An optimal layer‐design was found to be a key parameter in the optimization of strength with regard to different loading directions. Additionally, the maximization of the cohesion leads to a tremendous improvement in the mechanical performance of the printed parts, resulting in strengths of…

ABSTRACT Lignin, produced as a byproduct of pulp and paper and bioethanol industries, is a polyphenolic compound that has excellent potential to be used as phenol replacement in phenolic adhesive formulation. In this study, the phenol portion of phenol formaldehyde (PF) resin has been replaced by an agricultural‐based lignin, which was produced as a byproduct of a cellulosic bioethanol process through dilute‐acid pretreatment and enzymatic hydrolysis from corn stover. The PF resol resin was formulated using isolated lignin under alkaline condition. Chemical, physical, and thermal properties of the isolated lignin, PF resin and adhesive were measured using advanced analytical techniques such as Fourier transformed infrared spectroscopy (FTIR), size exclusion chromatography (SEC), phosphorous nuclear magnetic resonance spectroscopy (31P NMR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The developed 100% lignin‐based adhesive and a commercially formulated phenol resorcinol formaldehyde (PRF, as reference) were used to prepare single‐lap‐joint samples…

ABSTRACT The administration of active compounds by the oral mucosa is an efficient method for the delivery of drugs and nutrients. This work aimed to develop and characterize orally disintegrating films (ODFs) based on starch and gelatin as carriers of vitamin C. The ODFs were produced using a casting technique by varying the concentrations of starch and gelatin (0, 20, 40, 60, 80, and 100 g of starch/100 g of polymer) and were characterized in relation to contact angle, opacity, surface pH, infrared spectroscopy, mechanical properties, morphology, and disintegration time (in vitro and in vivo). Additionally, the stability of vitamin C in the ODFs was evaluated by the incorporation of the dry extract of acerola (4 g/100 g of filmogenic solution). Generally, the ODFs presented hydrophilic characteristics with a neutral surface pH near the mouth, and films with higher starch concentrations showed greater rigidity. In vitro and in vivo tests indicated that ODFs may be classified as rapidly disintegrating. The ODFs produced with higher concentrations of starch showed a higher stability…

ABSTRACT MXene, a recently‐discovered family of two‐dimensional (2D) transition metal carbides and/or nitrides, have attracted much interest because of their unique electrical, thermal, and mechanical properties. In this study, poly(acrylic acid), poly(ethylene oxide) (PEO), poly(vinyl alcohol) (PVA), and alginate/PEO were electrospun with delaminated Ti3C2 (MXene) flakes. The effect of small additions of delaminated Ti3C2 (1% w/w) on the structure and properties of the nanofibers were investigated and compared with those of the neat polymer nanofibers using scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, and Fourier transform infrared spectroscopy. Ti3C2 had an effect on the solution properties of the polymer and a greater effect on the average fiber diameter. The Ti3C2Tx/PEO solution exhibited the largest change in viscosity and conductivity with an 11% and 73.6% increase over the base polymer, respectively. X‐ray diffractograms demonstrated a high degree of crystallization for Ti3C2/PEO and a slight decrease in crystallinity for Ti3C2/PVA. ©…

ABSTRACT Crosslinked polyhydroxyurethane (PHU) networks synthesized from difunctional six‐membered cyclic carbonates and triamines are reprocessable at elevated temperatures through transcarbamoylation reactions. Here we study the structural effects on reprocessability and stress relaxation in crosslinked PHUs. Crosslinked PHUs derived from bis(five‐membered cyclic carbonates) are shown to decompose at temperatures needed for reprocessing, likely via initial reversion of the PHU linkage and subsequent side reactions of the liberated amine and cyclic carbonate. Therefore, several six‐membered cyclic carbonate‐based PHUs with varying polymer backbones and crosslink densities were synthesized. These networks show large differences in the Arrhenius activation energy of stress relaxation (from 99 to 136 kJ/mol) that depend on the network structure, suggesting that transcarbamoylation reactions may be highly affected by both chemical and mechanical effects. Furthermore, all crosslinked PHUs derived from six‐membered cyclic carbonates show mechanical properties typical of thermoset…

ABSTRACT The printable polyamide 12 (PA12) nanocomposite filaments with 6 wt % graphene nanoplatelets (GNPs) for fused deposition modeling (FDM) were prepared by melting compounding and smoothly printed via a commercial FDM three‐dimensional (3D) printer. The thermal conductivity (λ) and elastic modulus (E) of 3D printed PA12/GNPs parts along to the printing direction had an increase by 51.4% and 7% than that of compression molded parts, which is due to the GNPs preferentially aligning along to the printing direction. Along with these improved properties, ultimate tensile strength of 3D printed PA12/GNPs parts was well maintained. These results indicate that FDM is a new way to achieve PA12/GNPs parts with enhanced λ over compression moulding, which could contribute to realize efficient and flexible heat management for a wide range of applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45332.

ABSTRACT Multifunctional nanocomposites can be achieved by addition of modified layered nanoclays to impart to the final materials a designed set of properties. The easy reproducible preparation of copper modified montmorillonite has been reported here together with its spectroscopic characterization, including 29Si NMR in the solid state. Epoxy‐nanocomposites and glass fiber reinforced laminates containing 1% wt and 3% wt of Cu2+‐MMT have been prepared and characterized. Thermal and mechanical properties have been evaluated. The experiments carried out to evaluate the antibacterial activity showed that the epoxy‐resin nanocomposites with 3% wt of Cu2+‐MMT exhibited an inhibition action higher than 96% against Escherichia coli and Staphylococcus aureus. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44733.

ABSTRACT In this study, the influence of temperature and relative humidity on the plasticity controlled failure of polyamide 6 was investigated. Uniaxial tensile tests were performed at several temperatures, strain rates, and relative humidity; creep tests were performed at different relative humidity and applied load. In order to describe and predict the yield kinetics, the Ree–Eyring equation was employed and modified to include the effect of relative humidity. Subsequently, by the introduction of the concept of critical amount of accumulated plastic strain, the yield kinetics were successfully translated to predictions of time‐to‐failure. A good agreement between predictions and experimental results is obtained, showing that the model is a suitable and versatile tool to evaluate mechanical performance of a temperature and moisture sensitive material such as polyamide 6. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45942.

ABSTRACT In this article, a novel approach is presented for the preparation of small band‐gap polymer composites. The intensity of the surface plasmon resonance (SPR) peak increased from 0.64 to 3.2 for the chitosan–silver nitrate sample containing 1 wt % titanium dioxide (TiO 2 ). In the cases of 3 and 5 wt % added TiO 2 particles, the SPR peak disappeared. A wide shift of the absorption coefficient from 4.36 to 0.93 eV was observed. The smallest optical band gap of about 0.98 eV was achieved for the sample containing 3 wt % TiO 2 filler. The wide shift in the optical band gap was interpreted on the bases of the formation of metal‐induced gap states between the metallic silver particles and the TiO 2 structure. A novel approach was achieved that was an alternative method to Tauc's semi‐empirical model for band‐gap estimation. The optical dielectric loss parameter for the band‐gap study was easily calculated and analyzed, whereas it unfolded a deep knowledge from the physics point of view. The established quantum mechanical expression revealed a strong relationship between the…

ABSTRACT Lignin nanoparticles (nanolignin, NL) were prepared in this work by ultrasonic treatment of softwood kraft lignin to obtain lignin‐water dispersions with excellent colloidal stability. A thorough characterization of the chemical, physical, and morphological properties of the new NL particles allowed for direct comparisons with the untreated parent material. Such NL particles were incorporated into a waterborne thermoplastic polyurethane matrix at different concentrations to yield bio‐based nanocomposite materials. The effect of the bio‐filler type (NL vs. untreated lignin) and loading on the chemical, physical, thermal, and morphological characteristics of the resulting nanocomposites was extensively investigated. In addition, tensile tests carried out on these systems highlighted the superior mechanical properties of NL‐based nanocomposites compared to composite materials incorporating untreated lignin. The results of this study provide a direct demonstration of an easy and environmentally friendly approach to obtain waterborne polyurethane‐based nanocomposites reinforced…

ABSTRACT Rubber is one of the most versatile materials having myriad of applications—from niche rubber band and eraser to highly engineered spacecraft seal. Of late, the glittering concept of “sustainability” has been able to infiltrate within the domain of elastomer science and technology to a significant extent ‐ in both academia and industry. This fervent context thus necessitates a systematic documentation of brief history, present research scenario and future perspective of sustainable developments in this field. The present review aims to portray a panoramic sketch of various sustainable rubbers and functional rubber additives in this field and intends to provide a direction to their plausible future developments. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2018,135, 45701.

ABSTRACT In this study, carbon fiber–epoxy composites are interleaved with electrospun polyamide‐6,6 (PA 66) nanofibers to improve their Mode‐I fracture toughness. These nanofibers are directly deposited onto carbon fabrics before composite manufacturing via vacuum infusion. Three‐point bending, tensile, compression, interlaminar shear strength, Charpy impact, and double cantilever beam tests are performed on the reference and PA 66 interleaved specimens to evaluate the effects of PA 66 nanofibers on the mechanical properties of composites. To investigate the effect of nanofiber areal weight density (AWD), nanointerlayers with various AWD are prepared by changing the electrospinning duration. It is found that the electrospun PA 66 nanofibers are very effective in improving Mode‐I toughness and impact resistance, compressive strength, flexural modulus, and strength of the composites. However, these nanofibers cause a decrease in the tensile strength of the composites. The glass‐transition temperature of the composites is not affected by the addition of PA 66 nanofibers. © 2017 Wiley…

ABSTRACT The waste problem of the rebar inhibitors is very serious due to that it is a long time before they can exert their best effect in the concrete and they are kept losing all the time. However, there is still no effective solution to alleviate such situation. Meanwhile, drug delivery control technology based on environmental sensitive polymers has been successfully applied in biomedical fields. Thus, poly(acrylic acid)–acrylamide was synthesized as smart carrier for controlling rebar inhibitors delivery in concrete. Dipotassium hydrogen phosphate as model drug was encapsulated inside the polymeric particles via a self‐assembly process. The pH‐responsive activities of the polymeric particles were estimated by monitoring their swelling performances in solutions of different pH values and the drug delivery control characteristics were studied in simulated concrete pore solutions. The results indicate the polymeric particles deserve network structures with high porosity and exhibit excellent pH‐responsive activities, which can perform as perfect intelligent carriers whereas the…

Considerable effort has been made to improve ion‐exchange membrane (IEM) properties in order to achieve better performance of IEM‐based processes in various applications. Surface modification is one of the effective ways to improve IEM properties. Various methods have been used to modify IEM surfaces, for example, plasma treatment, polymerization, solution casting, electrodeposition, and ion implantation. These methods are able to produce a thin and fine distributed layer and also to modify the chemical structure of the surface. The new layer can be adsorbed, deposited, or chemically bonded on a membrane surface. By using these methods, IEM properties are improved, and the desired or specific characteristics such as high monovalent ion permselectivity, low fuel crossover, and anti‐organic‐fouling property can be obtained. In this paper, methods for surface modification of IEMs are reviewed. Moreover, the effects of modification on IEM properties and performance are discussed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45540.

ABSTRACT We investigated the dynamics of phase separation in a bisphenol A diglycidyl ether (BADGE)–poly(trimethylene terephthalate) (PTT) blend in this study, along with its effects on the long‐term mechanical properties of the blend. BADGE–PTT blends with 4,4′‐diaminodiphenyl sulfone were prepared by a conventional melt‐mixing technique followed by curing at 180 °C for 4 h. PTT is a rapidly crystallizing polymer because of its unique stereochemistry. The crystalline fraction of PTT is incompatible with BADGE, whereas the amorphous fractions are miscible. Similarly, the blend of BADGE and PTT represented a system with a strong dynamic asymmetry. We examined the effect of the curing (crosslinking) of BADGE in the system discussed previously, with a special emphasis on the viscoelastic properties and long‐term mechanical properties because they are extremely important in tuning these materials for various high‐performance applications in the aerospace industry. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45059.

ABSTRACT Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) was blended with poly(lactic acid) (PLA) with various reactive processing agents to decrease its brittleness and enhance its processability. Three diisocyanates, namely, hexamethylene diisocyanate, poly(hexamethylene diisocyanate), and 1,4‐phenylene diisocyanate, were used as compatibilizing agents. The morphology, thermomechanical properties, and rheological behavior were investigated with scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, tensile testing, dynamomechanical thermal analysis in torsion mode (dynamic mechanical analysis), and oscillatory rheometry with a parallel‐plate setup. The presence of the diisocyanates resulted in an enhanced polymer blend compatibility; this led to an improvement in the overall mechanical performance but did not affect the thermal stability of the system. A slight reduction in the PHBV crystallinity was observed with the incorporation of the diisocyanates. The addition of diisocyanates to the PHBV–PLA blend resulted in a notable increase in…

ABSTRACT The past few decades have seen extraordinary gain in interest for bio‐based products, driven by the intensifying call of the society for petrochemical material replacement and developing materials with next‐to‐no environmental impact. Cellulose, which is an abundantly available “green” material, can be derived from plant fibers and tailored for a plethora of possible uses where it can be used as a substrate or as a filler material. However, emerging technologies and product advancements necessitate the search for materials that are small, biodegradable, lightweight, and strong. Nanocellulose, which can be obtained through as mechanical and chemical production methods with tensile strength and Young's modulus of up to 0.5 and 130 GPa, respectively, proves to be the answer that they were looking for. However, the inherent hydrophilic nature of nanocellulose limited its potential widespread application. Surface modifications of nanocellulose to alter and diminish its hydrophilicity were done to address the aforementioned issues. In this article, we had reviewed on different…

ABSTRACT Active biodegradable poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) melt mixed nanocomposites and bilayer structures containing copper oxide (CuO) nanoparticles were developed and characterized. The bilayer structures consisted of a bottom layer of compression molded PHBV3 (3% mol valerate) coated with an active electrospun fibers mat made with CuO nanoparticles and PHBV18 (18% valerate) derived from microbial mixed cultures and cheese whey. The results showed that the water vapor permeability increased with the CuO addition while the oxygen barrier properties were slightly enhanced by the addition of 0.05 wt % CuO nanoparticles to nanocomposite films but a negligible effect was registered for the bilayer structures. However, the mechanical properties were modified by the addition of CuO nanoparticles. Interestingly, by incorporating highly dispersed and distributed CuO nanoparticles in a coating by electrospinning, a lower metal oxide loading was required to exhibit significant bactericidal and virucidal performance against the food‐borne pathogens Salmonella…

ABSTRACT A new polymer electrolyte based on the biopolymer Agar‐Agar doped with ammonium thiocyanate (NH4SCN) has been prepared and characterized by FTIR analysis, X‐ray diffraction measurements, AC impedance spectroscopy, transference number measurements, and DSC analysis. The Fourier transform infrared analysis confirms the complex formation between agar and NH4SCN. The amorphous nature of the polymer electrolyte has been revealed from X‐ray diffraction analysis. The highest ionic conductivity has been observed for the sample of composition 1:1 between Agar and NH4SCN. As a function of temperature, the ionic conductivity of this sample exhibits Arrhenius behavior increasing from 1.03 × 10−3 S cm−1 at ambient temperature to 3.16 × 10−3 S cm−1 at 343 K. The transference number has been estimated by the dc polarization method, and it has been proven that the conducting species are predominantly cations. Using the highest conductivity polymer electrolyte, solid state electrochemical cell has been fabricated and cell parameters are reported. © 2017 Wiley Periodicals, Inc. J. Appl.…

ABSTRACT Development of injectable, long‐lasting, contraceptive drug delivery formulations, and implants are highly desired to avoid unplanned pregnancies while improving patient compliance and reducing adverse side effects and treatment costs. The present study reports on the fabrication and characterization of two levonorgestrel (LNG) microsphere injectable formulations. Poly(ɛ‐caprolactone) (PCL) with 12.5% and 24% (w/w) LNG were fabricated into microspheres, measuring 300 ± 125 µm, via the oil‐in‐water (o/w) emulsion solvent evaporation technique. Formulations showed sustained drug release up to 120 days. FTIR, XRD, DSC, and TGA confirmed the absence of LNG chemical interaction with PCL as well as its molecular level distribution. The in vitro release of LNG was calculated to be Fickian diffusion controlled and properly characterized. The inclusion of multiple elevated release temperatures allowed for the application of the Arrhenius model to calculate drug release constants and representative sampling intervals, demonstrating the use of elevated temperatures for…

ABSTRACT The widespread application of poly(3‐hydroxybutyrate) (PHB) in the food packaging and biomedical fields has been hindered by its high brittleness, slow crystallization, poor thermal stability, and narrow processing window. To overcome these limitations, a mixture of biodegradable and biocompatible plasticizers was used to modify PHB. Epoxidized soybean oil (ESO), acetyl tributyl citrate, poly(ethylene glycol) 4000 (PEG4000), and poly(ethylene glycol) 6000 (PEG6000) were tested to improve PHB melt processing and to achieve balanced thermal and mechanical properties. These plasticizers increased the flexibility and decreased the melt viscosity, improving the processability. The tensile strength was maintained within the limit of experimental error for ESO and decreased slightly (6–7%) for the other plasticizers. PEG6000 and ESO delayed the decomposition process of PHB. The plasticizers did not hinder the crystallization, and poly(ethylene glycol)s increased the crystallinity. The change in the interplanar distance and crystallite size, correlated with lamellar stack…

ABSTRACT Technologies for energy harvesting from objects in motion are gaining a continuously increasing interest to directly power wearable electronics, sensors, and wireless transmitters. New networks where things will be uniquely identified and interconnected will require key enabling technologies, particularly cheap, flexible generators of renewable energy, conformable to any solid surface, to power independently individual objects and data transmission. Polymer‐based nanogenerators (PNGs), capable of converting mechanical energy into electricity, have exact features to fulfill these requirements. This article highlights advances in PNGs with focus on material chemistries and geometrical features, device design strategies, and performances. Representative examples of applications which show large‐scale capability are reported. Concluding sections summarize the key challenges and the commercialization perspectives of PNGs for use in real life applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45674.

ABSTRACT This study explores the plasticizing effect of coconut oil (CO) on PLA for evaluating its suitability for flexible packaging. Changes in morphological, mechanical, thermal, rheological, barrier and optical properties of melt compounded Poly(lactic acid)–Coconut oil (PLA–CO) blend were investigated by varying the mixing ratio. Water vapor permeability of blends decreased by 58% at 7 wt % plasticizer content. The tensile strength showed a decreasing trend with increasing plasticizer percentage while the % elongation showed an increasing trend. At 7 wt % plasticizer content tensile strength decreased from 60 to 41 MPa and % elongation increased from 12% to 54%. Molecular weight (Mn) and onset of degradation (Tonset), upon 1 wt % plasticizer addition showed a reduction of 6% and 0.6%, respectively, which were well within permissible limits required for polymer processing. The melt flow properties of the blends were slightly improved (∼16%) upon 5 wt % addition of CO. Transparency of the PLA films was improved by addition of plasticizer. FTIR spectra of PLA‐CO sample confirmed…

ABSTRACT Light (0.089–0.12 g cm−3), superabsorbent (84–99 g water/1 g aerogel), and highly flame retardant non‐crosslinked cellulose aerogel (CA) and crosslinked cellulose aerogel (CL‐CA) have been successfully produced from pruning waste of blueberry tree. The prepared aerogels with three dimensional porous structure have a remarkably thermal stability and flame retardant performance, which totally burned after 136–200 s. Besides, CA and CL‐CA have an important Brunauer–Emmet–Teller surface area, which are 348 and 275 m2 g−1, respectively. The concepts of this study are simple and bio‐wastes are easily available and sustainable at low cost, and therefore, the current process is appropriate for industrial scale production and has a significant potential in the future of green materials. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45315.

ABSTRACT In this study, activated carbon (AC) was synthesized by chemical activation process from rice husk, with the BET surface area of 2180 m2/g. Chitosan/poly(ethylene oxide) (PEO)/AC nanofibrous membrane (CPANM) was synthesized by electrospinning process. The average fiber diameter was found to be 83 ± 12.5 nm. Incorporation of AC lead to increase in the surface area of CPANM than chitosan/PEO fiber (CPF) by 371 m2/g. X‐ray photoelectron spectroscopy survey and narrow scan analysis further proved the presence of AC in the membrane. CPANM showed higher adsorption capability than CPF. Analysis of the mechanism of heavy metals adsorption by CPANM and CPF hypothesized that, (NH2) is the only active group in CPF, whereas both (NH2) and (COOH) contributed in adsorption for CPANM. Maximum adsorption capacity of CPANM for Cr(VI), Fe(III), Cu(II), Zn(II), and Pb(II) ion was found to be 261.1, 217.4, 195.3, 186.2, and 176.9 mg g−1 respectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45851.

ABSTRACT This article presents research results showing that the property of fused deposition modeling (FDM) products is obtained jointly by careful control of processing parameters, structure of products, and the composition of material. In this manuscript, poly(lactic acid) (PLA) was incorporated with graphene or carbon nanotube (CNT) through repeated melt blending. Filament of the PLA/graphitic nano‐filler was prepared and used in FDM. Rheological and thermal analysis were conducted to assess the suitability of the composite as FDM feedstock, and mechanical and electrical property were tested subsequently. Research results demonstrate that filament diameter‐regarded as processing‐related parameter‐was positively correlated with mechanical stiffness and strength of FDM products. Tensile elongation at break of FDM products exhibited significant increase at a raster angle of 45° compared with the filament before FDM, showing in certain cases, material property depends more on the structure than the composition. And when incorporated with graphene or CNT, the electrical conductivity…

ABSTRACT Flexible and wearable smart fabrics are becoming increasingly popular in healthcare and motion monitoring because of their potential applications in flexible and stretchable electronics. The integration of ordinary fabric with conductive fillers provides the fabric with new and intriguing functions, such as sensation. In this study, a low‐cost and efficient manner was used to fabricate a highly reliable conductive composite on fabric as an effective sensing material for gesture recognition. A strain sensor was fabricated by the incorporation of the highly conductive polyaniline (PANI) polymer, graphene nanoplatelets (GNPs), and a handful of silicon rubber (SR) onto elastic Lycra fabric via a spin‐coating method. We demonstrated that the fabric strain sensor was able to detect and monitor the bending angle of a human finger. By means of the covered structure of the PANI and GNPs, the composite fabric could bear a 40% maximum strain and possess the pleasant characteristic of stretching and bending. The gauge factor of the fabric strain sensor reached 67.3; this was an…

ABSTRACT Poly(hydroxyurethane)s (PHUs) are desired to replace PolyUrethanes (PUs) which are synthesized using harmful isocyanates. Nevertheless, the synthesis of PHUs starting from cyclocarbonates and amines displays two major drawbacks: the low reactivity observed during the opening of (poly)cyclocarbonates by (poly)amines and the low molar masses of polymers obtained. Currently, intensive work is carried out in order to increase the efficiency of the aminolysis of cyclocarbonates reaction but very few is dedicated to explaining the limitations of molar masses of PHUs. This article aims at demonstrating that the low molar masses can be explained by the existence of side reactions and the incomplete conversion of monomers during the polymerization. These conclusions were obtained after complete DSC and NMR studies that evidence that the incomplete conversion of monomers and therefore the low molar masses are caused mainly by hydrogen bonding and partly by the formation of urea. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 44958.

ABSTRACT Effective dissolution of cellulosic macromolecules is the first predominant step to prepare functional bio‐based materials with desirable properties. In this study, we developed an improved dissolution process using a freeze‐drying pretreatment to promote the dissolution of cellulose. Rheological measurements of cellulose solutions and physicochemical characterization of regenerated cellulose films (scanning electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, and thermogravimetric analysis) were performed. Cellulose solution prepared from 5% microcrystalline cellulose (w:v) in the solvent exhibits a Newtonian fluid character while cellulose solutions at higher concentrations show a pseudo‐plastic fluid behavior. Results from physicochemical characterization indicate that a freeze‐drying pretreatment step of cellulose leads to a complete dissolution at 5% concentration while only part of cellulose is dissolved at 10% and 15% concentrations. The results obtained indicated that the use of a freeze‐drying pretreatment step under mild conditions lead…

ABSTRACT The aim of this study was to analyze how corona dosages above recommended levels affect film surface energy and hydrophobic recovery of such treated film surfaces as well as laminate bond strength of laminates made of these films. The adhesive for lamination was a polyurethane‐adhesive with a dry film thickness of ∼5 µm. Polar and dispersive parts of the surface energy were measured frequently according to DIN 55660‐2 (Owens–Wendt–Rabel‐and‐Kaelble method) for up to 140 days after corona treatment. The corona dosage had a value of up to 280 W min/m2. Laminate bond strength was measured according to DIN 55543‐5. The effect of corona treatment was highest for low‐density polyethylene (PE‐LD) films, mean for biaxial‐oriented polypropylene (PP‐BO) films, and lowest for biaxial‐oriented poly(ethylene terephthalate) (PET‐BO) films. With increasing storage time, surface energy decreased, as expected. The higher the effect of corona treatment, the faster the polar part of surface energy decreased. At PE‐LD, laminate bond strength increased with a higher corona dosage from 0.05 to…

ABSTRACT Soy proteins are gaining more and more attention because of its multifunction and biodegradability. Silver nanoparticles (AgNPs) are introduced into the nanofibers to prevent growth of microorganisms over the filter media. In the present study, the multifunctional and antimicrobial nanofibrous membranes were prepared by electrospinning the soy protein isolate (SPI)/polymide‐6 (PA6)‐silver nitrate system followed by ultraviolet reduction. The morphology of SPI/PA6 nanofibrous membranes was characterized by scanning electron microscopy. Antibacterial property of nanofibrous membranes were investigated against Escherichia coli and Bacillus subtilis. The optimized fiber membrane exhibited over 95% filtration efficiency of PM0.3 (particulate matter size less than 0.3 μm). The successful synthesis of SPI/PA6‐AgNPs nanofibrous membranes would make it to be the potential candidate for novel antibacterial and high‐performance air filter. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45766.

ABSTRACT Dual components of a self‐healing epoxy system comprising a low viscosity epoxy resin, along with its amine based curing agent, were separately encapsulated in a polyacrylonitrile shell via coaxial electrospinning. These nanofiber layers were then incorporated between sheets of carbon fiber fabric during the wet layup process followed by vacuum‐assisted resin transfer molding to fabricate self‐healing carbon fiber composites. Mechanical analysis of the nanofiber toughened composites demonstrated an 11% improvement in tensile strength, 19% increase in short beam shear strength, 14% greater flexural strength, and a 4% gain in impact energy absorption compared to the control composite without nanofibers. Three point bending tests affirmed the spontaneous, room temperature healing characteristics of the nanofiber containing composites, with a 96% recovery in flexural strength observed 24 h after the initial bending fracture, and a 102% recovery recorded 24 h after the successive bending fracture. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44956.

ABSTRACT Varying amounts of exfoliated graphene oxide (GO) are systematically incorporated into nanoscale polyacrylonitrile (PAN) fibers via an electrospinning method. Subsequent treatment of the PAN–GO composite nanofibers under a moderate temperature and high pressure leads to the formation of membrane sheets with enhanced mechanical properties. scanning electron microscope, Fourier transform infrared spectroscopy, and contact angle measurements confirm the successful incorporation of the GO into the PAN nanofiber membranes whose diameter, porosity, and pore size are notably influenced by the amount of the GO content. These composite membranes also exhibit a gradual reduction in the water contact angle as a function of the hydrophilic GO content, resulting in a beneficial property for water purification. In addition, the proper integration of GO into the PAN nanofibers improves the protein rejection rate and water flux during the filtration process, which indicates the possibility of utilizing these types of composite membranes in water treatment systems. © 2017 Wiley Periodicals,…

ABSTRACT Boehmite is an aluminum oxyhydroxide [AlO(OH)] which is preferentially used as precursor for the production of (transition) aluminum oxides. Boehmite alumina (BA) nanoparticles are available in various morphologies due to versatile synthesis routes, which are briefly introduced. The peripheral hydroxyl groups of BA offer manifold functionalization possibilities for tailoring the dispersion and filler/matrix adhesion properties. The incorporation of BA nanofillers, with and without surface treatments, may yield improved mechanical and novel functional properties in polymers. BA can be introduced in polymers and polymer composites through different methods. This comprehensive overview covers the basic results reported on polymer/BA nanocomposites in the open literature. In this review, polymer matrices are grouped into thermoplastics, thermosets, and rubbers. Using literature results and our own findings, we have identified promising R&D trends with polymer/BA nanocomposites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45573.

ABSTRACT Biodegradable films, with starch as a matrix, were developed and reinforced with wheat and corn hulls. The effect of the particle size of the filler on the microstructure and mechanical and barrier properties of starch‐based films was investigated. We observed that the addition of hulls enhanced the modulus, tensile strength, and impact strength of the starch matrix at the expense of its elongation. The water‐vapor transmission rate results show that corn starch was more efficient in reducing the water‐vapor permeability than wheat hulls. Scanning electron microscopy observations indicated that the compatibility of both fillers with the matrix was quite good; this was expected because all of the components used in this study were hydrophilic and exhibited polar behavior. Optical microscopy and X‐ray diffraction observations indicated that the processing conditions did not affect the crystalline and geometric structures of the hulls. Because all of the components used in this study were from food resources, the films could also be used for edible packaging. © 2017 Wiley…

ABSTRACT α‐Tocopherol (α‐TC) and α‐TC/cyclodextrin (CD)–inclusion complex (IC) incorporated electrospun poly(lactic acid) (PLA) nanofibers (NF) were developed via electrospinning (PLA/α‐TC–NF and PLA/α‐TC/γ‐CD–IC–NF). The release of α‐TC into 95% ethanol (fatty food simulant) was much greater from PLA/α‐TC/γ‐CD–IC–NF than from PLA/α‐TC–NF because of the solubility increase in α‐TC; this was confirmed by a phase‐solubility diagram. 2,2‐Diphenyl‐1‐picrylhydrazyl radical‐scavenging assay shows that PLA/α‐TC–NF and PLA/α‐TC/γ‐CD–IC–NF had 97% antioxidant activities; this value was expected to be high enough to inhibit lipid oxidation. PLA/α‐TC–NF and PLA/α‐TC/γ‐CD–IC–NF were tested directly on beef with the thiobarbituric acid reactive substance (TBARS) method, and the nanofibers displayed a lower TBARS content than the unpackaged meat sample. Thus, active packaging significantly enhanced the oxidative stability of the meat samples at 4 °C. In conclusion, PLA/α‐TC/γ‐CD–IC–NF was shown to be promising as an active food‐packaging material for prolonging the shelf life of foods. © 2017…

ABSTRACT A multi‐functional epoxide oligomer, Joncryl ADR‐4368 (ADR), is used as a modifier to prepare foamable poly(ethylene terephthalate) (PET) by reactive extrusion and compared with common tetra‐functional modifier pyromellitic anhydride (PMDA) as a reference. Torque evolution reveals that ADR has a faster reaction with PET than PMDA. The reactions generate long‐chain branches and gel structures, which are confirmed by rheological methods. Shear rheological studies show that PET modified with both ADR and PMDA display higher complex viscosity and lower loss tangent than unmodified sample. In particular, at a given viscosity level, ADR leads to a lower loss tangent than PMDA. Moreover, compared to PMDA, the addition of ADR results in a higher die pressure during extrusion and a more pronounced strain hardening during uniaxial elongation. These results indicate that ADR‐modified PET is less viscous but more elastic than PMDA‐modified PET. Owing to the higher elastic properties, ADR‐modified PET presents better foaming performance in batch foaming process with CO2 as a blowing…

ABSTRACT Graphene‐nanoplateles (Gr) and multiwalled carbon nanotubes (CNTs) reinforced epoxy based composites were fabricated using ultrasonication, a strong tool for effective dispersion of Gr/CNTs in epoxy. The effect of individual addition of two different nanofillers (Gr and CNT) in epoxy matrix, for a range of nanofiller content (0.1–1 wt %), has been investigated in this study. This study compares mechanical and thermomechanical behavior of Gr and CNT reinforced epoxy. Gr reinforcement offers higher improvement in strength, Young's modulus, and hardness than CNT, at ≤0.2 wt %. However, mode‐I fracture toughness shows different trend. The maximum improvement in fracture toughness observed for epoxy‐Gr composite was 102% (with 0.3 wt % loading of Gr) and the same for epoxy‐CNT composite was 152% (with 0.5 wt % loading of CNT). Thorough microstructural studies are performed to evaluate dispersion, strengthening, and toughening mechanisms, active with different nanofillers. The results obtained from all the studies are thoroughly analyzed to comprehend the effect of nanofillers,…

ABSTRACT Six fillers from forestry wastes (wood, bark, cones and needles from young pine trees, kraft lignin, and recycled paper sludge from industry wastes) were incorporated into polyurethane (PU)‐based foams prepared via free‐rise pouring method. Variable filler contents (1, 5, and 10 wt %) and NCO/OH ratios (0.6, 0.9, and 1.2) were investigated. A simple mixture (1:3) of castor oil and crude glycerin (byproduct from biodiesel production) was used as biobased polyol. The foam composites were investigated through spectroscopy, morphological, mechanical, and hygroscopic analyses. The addition of fillers decreased water uptake and yielded rigid PU systems with more homogenous cell structure. The 1% and 5% reinforcement wood were the most effective among the studied compositions, with better mechanical and hygroscopic performance, probably due the higher compatibility of the wood with the PU system, which promote urethanic bonds between filler and isocyanate, as indicated by wet chemical results and micrographs. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45684.

ABSTRACT Several expandable graphites (EGs), differing in expansion volume but with the same mean size, are compared as flame retardants in polyurethane (PUR) foams. Not only common sulfur‐intercalated graphites are investigated but also a new one intercalated with phosphorus. The main aim of this article is to understand which properties of EG are important for its flame retardancy effectiveness in PUR foams. Thermal stability, flammability, and fire behavior are analyzed through limiting oxygen index and cone calorimeter tests. Detailed characterization of the phosphorus‐intercalated graphite is also provided as well as physical–mechanical characterization. The results show that the well‐known sulfur‐intercalated graphites and the one with phosphorus both enhance the residue yield, induce a protective layer, and thus efficiently flame‐retard PUR foams. While the expansion volume of the EGs had a surprisingly limited influence on the performance of the foams, at least in the range tested, the most important feature controlling the effectiveness of EG in terms of flame retardant PUR…

ABSTRACT Amine‐terminated hyperbranched polymer (HBP‐NH2), as an inhibitor in water‐based drilling fluid, is prepared by the polycondensation of diamine AB2 monomers. The primary amine and secondary amide structures are confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy. Through time of flight mass spectrometry, the molecular weight of HBP‐NH2 is mainly distributed in the range of 200–1400. Also, the quasi‐spherical shape and the high temperature resistance (200 °C) performance of HBP‐NH2 are, respectively, certified through the environmental scanning electron microscope and the thermogravimetric analysis. In the inhibition performance test, the linear expansion rate of sodium bentonite in 3 wt % HBP‐NH2 aqueous solution is only 11.42%, which is lower than other inhibitors (KCl, FA‐367, and HPAM). Zeta potential analysis shows that HBP‐NH2 has a strong ability to inhibit the hydration and dispersion of sodium bentonite by protonated primary amine groups. Compared with the base slurry, the absolute value of zeta potential is…

ABSTRACT Miscanthus fibers reinforced biodegradable poly(butylene adipate‐co‐terephthalate) (PBAT) matrix‐based biocomposites were produced by melt processing. The performances of the produced PBAT/miscanthus composites were evaluated by means of mechanical, thermal, and morphological analysis. Compared to neat PBAT, the flexural strength, flexural modulus, storage modulus, and tensile modulus were increased after the addition of miscanthus fibers into the PBAT matrix. These improvements were attributed to the strong reinforcing effect of miscanthus fibers. The polarity difference between the PBAT matrix and the miscanthus fibers leads to weak interaction between the phases in the resulting composites. This weak interaction was evidenced in the impact strength and tensile strength of the uncompatibilized PBAT composites. Therefore, maleic anhydride (MAH)‐grafted PBAT was prepared as compatibilizer by melt free radical grafting reaction. The MAH grafting on the PBAT was confirmed by Fourier transform infrared spectroscopy. The interfacial bonding between the miscanthus fibers and…

ABSTRACT Liquid resins‐based three‐dimensional (3D) printing techniques such as stereolithography and digital light processing (DLP) show higher resolution and accuracy than other printing techniques, but their applications have been impeded by the limited materials selection and lack of functions. We here reported the preparation of luminescent resins for DLP‐based 3D printing. Homogeneous dispersion of the fluorescent dyes was achieved by small acrylate molecules screening, and the cure depth studies was used to optimize both resin composition and printing parameters setting. In addition, we showed that the optical analysis of absorption and emission spectra is an important tool to reduce the complex mutual‐interference of the light absorption of dye, photoinitiator and photo‐absorber in the printable resin. We also developed the mater batch technique to tune the emitting colors in the whole visible range, together with white emitting. By using the developed resins, different 3D structures with different emitting colors were successfully printed by DLP technique. These results…

ABSTRACT Electrospun poly[(vinylidene fluoride)‐co‐hexafluoropropylene]/silica (PVdF‐HFP/SiO2) nanocomposite polymer membranes (esCPMs) were prepared by incorporating different weight percentages of SiO2 nanoparticles onto electrospun PVdF‐HFP by electrospinning technique. The surface morphology of electrospun PVdF‐HFP nanocomposite membranes was characterized by scanning electron microscopy. The effect of SiO2 nanoparticles incorporation onto electrospun PVdF‐HFP polymer membranes (esPMs) has been studied by XRD, DSC, TGA, and tensile analysis. The electrospun PVdF‐HFP/SiO2 based nanocomposite membrane electrolytes (esCPMEs) were prepared by soaking the corresponding esCPMs into 1 M LiPF6 in EC:DMC (1:1 vol/vol %). The ionic conductivity of the esCPMEs was studied by AC‐impedance studies and it was found that the incorporation of SiO2 nanoparticles into PVdF‐HFP membrane has improved the ionic conductivity from 1.320 × 10−3 S cm−1 to 2.259 × 10−3 S cm−1. The electrochemical stability of the esCPME was studied by linear sweep voltammetry studies and it was found to be 2.87 V.…

ABSTRACT Fused deposition molding (FDM) is the most popular technology in the fields of three‐dimensional printing, but it is hard to use a variety of plastic materials due to the limitation of filament form of material. Using plastic pellets as printing materials gives advantages in cost, processing speed, and available materials. In this work, a large‐scale double‐screw FDM three‐dimensional printer based on plastic pellets has been designed. It is capable of printing large plastic products at a low cost and high speed. Using ABS + 10%GF as printing material, this work is first focused on the effects of the pressure and speed of the metering screw on the flowrate of melt. The equation for the relationship of these three parameters was established as well. Based on this equation, the effects of melt flow, printing speed, and layer thickness on the width of fused filament were investigated with experiments. Furthermore, the effects of printing spacing between fused filaments on surface accuracy and bonding strength were also explored. By printing models, it was revealed that the…

ABSTRACT In this study, graphite oxide (GO) is synthesized from natural graphite flakes by the modified Hummers method. Characterization by Fourier transform infrared, X‐ray photoelectron, Raman and ultraviolet‐visible spectroscopies, X‐ray diffraction, and thermogravimetric analysis is conducted on GO to confirm the oxidation of graphite. Unplasticized and glycerol plasticized chitosan/graphene oxide (CS/GO) nanosheets nanocomposites with different GO loadings are prepared by solution casting. The combined effect of GO and glycerol on structure, thermal and mechanical properties of nanocomposite films is studied. GO nanosheets are well dispersed throughout the CS matrix due to the hydrogen bonding and electrostatic interactions between CS and GO nanosheets. The incorporation of GO within the CS matrix results in a decrease of the crystallinity, an improvement of thermal stability, and a significant enhancement of the stiffness and tensile strength that is emphasized by the glycerol. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45092.

ABSTRACT In the challenging prospect of developing new materials by mixing different polymers to reach a synergetic performance, the present research focuses on the study of the miscibility of two polymers: The acrylonitrile butadiene styrene (ABS) composed of a dispersed elastomeric (polybutadiene rubber) polymer embedded in a SAN thermoplastic matrix, and the polycarbonate (PC). It shall be noted that obtaining miscible polymer blends is often a difficult task because of the large size of their molecular chains and the high interfacial tension between the polymer phases. Until now, the most numerous researches developed in this field involve polymer blends obtained by compatibilization techniques in order to improve the interfacial adhesion between initial polymers. The aim of this work is to study the miscibility between ABS and PC. First, two different methods were used to mix the polymers: the twin‐screw extrusion and the dissolution in a common solvent tetrahydrofuran (THF). Then, physicochemical, microscopic observation and rheological characterization were performed on…

ABSTRACT Traditional lignin pyrolysis generates a bio‐oil with a complex mixture of alkyl‐functionalized guaiacol and syringol monomers that have limited utility to completely replace phenol in resins. In this work, formate assisted fast pyrolysis (FAsP) of lignin yielded a bio‐oil consisting of alkylated phenol compounds, due to deoxyhydrogenation, that was used to synthesize phenol/formaldehyde resins. A solvent extraction method was developed to concentrate the phenolics in the extract to yield a phenol rich monomer mixture. Phenolic resins were synthesized using phenol (phenol resin), FAsP bio‐oil (oil resin), and an extract mimic (mimic resin) that was prepared to resemble the extract after further purification. All three phenolic sources could synthesize novolac resins with reactive sites remaining for subsequent resin curing. Differential scanning calorimetry and thermogravimetric analysis of the three resins revealed similar thermal and decomposition behavior of phenol and the mimic resins, while the oil resin was less stable. Resins were cured with hexamethylenetetramine…

ABSTRACT A semi‐interpenetrating network system [(GG‐g‐PAAm)‐PVA] was made by microwave irradiation of aqueous mixture of gellan gum (GG), acrylamide (AAm), and poly(vinyl alcohol) (PVA) containing N,N′‐methylene‐bis‐acrylamide as crosslinking agent. The gel was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, X‐ray diffraction, and scanning electron microscopy techniques. The swelling behavior was studied under different pH conditions. A pH‐dependent swelling with maximum swelling under neutral pH was observed. The swelling process is found to follow second‐order kinetics and the mechanism of water transport is found to be Fickian type of diffusion. The (GG‐g‐PAAm)‐PVA was evaluated for removal of dye from aqueous solution, using crystal violet, a cationic dye. The maximum adsorption capacity of the gel was found to be 45.45 mg/g. The kinetic studies revealed a second‐order adsorption process which fits well into Langmuir model. The evaluation of thermodynamic parameters indicated the adsorption process to be exothermic and spontaneous at lower…