Showing papers in "Journal of Applied Polymer Science in 2016"

Recent advances in bio‐based epoxy resins and bio‐based epoxy curing agents

Abstract: The combination of awareness of harmful industrial processes and environmental issues and depleting petroleum-based resources has spurred much research in developing materials from renewable sources. Epoxy resins are common pre-polymers used in a variety of industries, such as adhesives, coatings, insulations, and high performance composites. To transform epoxy resins into crosslinked networks with desirable thermal and mechanical properties, the resins must be cured with a curing agent. This review encompasses recent developments using bio-based epoxy resins and bio-based epoxy curing agents. Resins and curing agents synthesized from modified plant oils, sugars, polyphenols, terpenes, rosin, natural rubber, and lignin are highlighted and their thermal and mechanical properties reviewed. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44103.

Laccase‐catalyzed synthesis of conducting polyaniline‐lignosulfonate composite

Abstract: This work was financially supported by National Natural Science Foundation of China (21274055, 51173071), Program for New Century Excellent Talents in University (NCET-12-0883), the Fundamental Research Funds for the Central Universities (JUSRP51312B), China Scholarship Council and the Graduate Student Innovation project (KYLX_1140).

Active edible films: Current state and future trends

Abstract: Active edible films represent one of the current and future trends in the development of new polymers for selected applications, particularly food packaging. Some biopolymers show excellent performance as carriers for active compounds extracted from natural sources and are able to be released at a controlled rate to packaged food. In this review we aim to present, in a comprehensive way, the most recent advances and updates in this subject, where much research is currently ongoing and new studies are reported very often. This review focuses on innovative biopolymer matrices, their processing to obtain edible active films, and present and future applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42631.

Electrospun biodegradable nanofibers scaffolds for bone tissue engineering

Abstract: Many polymeric materials have been developed and introduced for bone regeneration. Especially, their nanofibrous forms are mostly applied for artificial extracellular matrices. Polymeric materials in their nanofibrous form show some potent properties such as high surface-to-volume ratio, tunable porosity, and ease of surface functionalization. Benefiting from the properties of their main polymer and additives, they can provide new opportunities for cell seeding, proliferation, and new 3D-tissue formation. This article focuses on most cited polymeric nanofibrous scaffolds fabricated by electrospinning and recent achievements. They were divided into two main categories: natural (collagen, silk, keratin, gelatin, chitosan, and alginate) and synthetic (e.g., polycaprolactone, polylactic acid, and polyglycolic acid) polymers. The role of several additives like hydroxyapatite, bone morphogenetic proteins (BMPs), tricalcium phosphate, and collagen type I in improving the adhesion, differentiation, and tissue formation of stem cells were discussed. Finally, the osteogenic capacity and ability of nanofibrous scaffolds to support the growth of clinically relevant bone tissue were briefly studied. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42883.

Recent advances in carbon fibers derived from biobased precursors

Abstract: High-performance carbon fibers (CFs) are currently produced primarily from polyacrylonitrile (PAN). However, the high cost of such CFs and the environmental concerns during its manufacturing (from PAN) are stimulating research on alternative bio-based precursors and environmentally friendly processing routes. This review summarizes the recent research studies on the pathways for converting cellulose and lignin (most abundant and renewable biomass) into suitable precursor fibers and CFs. The role of various bio-based precursors, fiber spinning routes, and process conditions on the final properties of CFs is discussed. Although bio-based CFs reported in the current research studies have limited strength and modulus to be considered for high-performance aerospace applications, further progress in precursor purification and optimized fiber processing may lead to their application in less demanding structural applications such as automotive and industrial. Even in their current state, a lack of graphitic crystallinity results in a lower conductivity for the resulting CFs and makes them suitable for ultrahigh temperature insulative applications. Furthermore, the noncrystalline form of carbon obtained from bio-based precursors clearly indicates a significant potential of carbon nanofibers, mats, and activated CFs in nonstructural applications that require a large specific surface area, such as electrochemical energy storage and purification. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43794.

A novel approach for extracting cellulose nanofibers from lignocellulosic biomass by ball milling combined with chemical treatment

Abstract: Cellulose nanofibers (CNFs) were isolated from kenaf fibers and wheat straw by formic acid (FA)/acetic acid (AA), peroxyformic acid (PFA)/peroxyacetic acid (PAA), hydrogen peroxide (H2O2) treatment; and subsequently through ball milling treatment. Characterization of extracted cellulose and cellulose nanofibers was carried out through Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). TEM images showed that extracted cellulose nanofibers had diameter in the range of 8–100 nm. FTIR and XRD results implied that hemicellulose and lignin were mostly removed from lignocellulosic biomass with an increase in crystallinity, and isolation of cellulose nanofibers was successful. The TGA results showed that decomposition temperature of cellulose nanofibers increased by about 27°C when compared with that of untreated lignocellulosic biomass. No significant change was observed in the decomposition temperature of bleached celluloses after ball milling. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42990.

Effects of polyethyleneimine molecular weight and proportion on the membrane hydrophilization by codepositing with dopamine

Abstract: Mussel-inspired chemistry has attracted widespread interest in the surface modification of polymer membranes. We have previously demonstrated a dopamine (DA) assisted codeposition process of polyethyleneimine onto polypropylene microfiltration membranes (PPMMs) for surface hydrophilization. In this work, we further investigate the effects of PEI molecular weight and DA/PEI mass ratio on the codeposition process and membrane performance. The results indicate that only low-molecular-weight PEI bring a distinct promotion in both surface wettability and water permeation flux for PPMMs. On the other hand, either excess DA or PEI is detrimental to the surface hydrophilicity of the studied membranes. The optimized PEI molecular weight is 600 Da and the corresponding mass ratio is 1:1 for the surface hydrophilization of PPMMs. These results are beneficial to understand those codeposition processes of dopamine with other polymers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43792.

Electrospun poly(hydroxybutyrate)/chitosan blend fibrous scaffolds for cartilage tissue engineering

Abstract: In this study, polyhydroxybutyrate (PHB) was blended with chitosan (CTS), and electrospun in order to produce more hydrophilic fibrous scaffolds with higher mass loss rates for cartilage tissue engineering application. First, the effects of diverse factors on the average and distribution of fiber's diameter of PHB scaffolds were systematically evaluated by experimental design. Then, PHB 9 wt % solutions were blended with various ratios of CTS (5%, 10%, 15%, and 20%) using trifluoroacetic acid as a co-solvent, and electrospun. The addition of CTS could decrease both water droplet contact angle from ∼74° to, ∼67° and tensile strength from, ∼87 MPa to ∼31 MPa. According to the results, the scaffolds containing 15% and 20% CTS were selected as optimized scaffolds for further investigations. Mass loss percentage of these scaffolds was directly proportional to the amount of CTS. Chondrocytes attached well to the surfaces of these scaffolds. The findings suggested that PHB/CTS blend fibrous scaffolds have tremendous potentials for further investigations for the intended application. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44171.

Fabrication of PCL/β-TCP scaffolds by 3D mini-screw extrusion printing

Abstract: Scaffolds of polycaprolactone (PCL) and PCL composites reinforced with β-tricalcium phosphate (β-TCP) were manufactured aiming potential tissue engineering applications. They were fabricated using a three-dimensional (3D) mini-screw extrusion printing, a novel additive manufacturing process, which consists in an extrusion head coupled to a 3D printer based on the Fab@Home equipment. Thermal properties were obtained by differential scanning calorimetry and thermogravimetric analyses. Scaffolds morphology were observed using scanning electron microscopy and computed microtomography; also, reinforcement presence was observed by X-ray diffraction and the polymer chemical structure by Fourier transform infrared spectroscopy. Mechanical properties under compression were obtained by using a universal testing machine and hydrophilic properties were studied by measuring the contact angle of water drops. Finally, scaffolds with 55% of porosity and a pore size of 450 μm have shown promising mechanical properties; the β-TCP reinforcement improved mechanical and hydrophilic behavior in comparison with PCL scaffolds. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43031.

Structural and antibacterial properties of a γ-radiation-assisted, in situ prepared silver–polycarbonate matrix

Abstract: A silver–polycarbonate (Ag–PC) matrix was prepared by a g-radiation-assisted diffusion method, and its antibacterial properties were studied. Rutherford backscattering spectroscopy, X-ray diffraction, and transmission electron microscopy results showed the diffusion of good, crystalline-structured (face-centered cubic) silver nanoparticles (AgNPs) inside polycarbonate (PC) after irradiation. Ultraviolet–visible spectroscopic results indicated a blueshift in the surface plasmon resonance of the AgNPs; this revealed a particle size decrease with increasing g-radiation dose. This was also supported by the scanning electron microscopy results. The microstructure of the pristine PC and silver-doped PC was monitored with positron annihilation spectroscopy, and it showed decreases in the free-volume hole size and fractional free-volume for Ag–PC and g-ray-irradiated PC. This corroborated the Doppler broadening spectroscopy results. The thermal degradation temperature of PC was increased because of the diffusion of AgNPs in PC. The antibacterial activity of the synthesized Ag–PC matrix was evaluated by the zone of inhibition, and the results demonstrated its bacterial growth inhibition ability. The results indicate the potential to produce an Ag–PC matrix for various applications in medical and food industries. VC 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43729.

Surface-modified MgO nanoparticle enhances the mechanical and direct-current electrical characteristics of polypropylene/polyolefin elastomer nanodielectrics

Abstract: Polypropylene (PP)/polyolefin elastomer (POE) blends and MgO/PP/POE nanocomposites were fabricated by melt blending. The morphology, mechanical, and electrical properties of the nanocomposites were investigated. Scanning electron microscopy showed that the surface-modified MgO nanoparticles were well dispersed in the polymer matrix at low loadings of less than 3 phr. X-ray diffraction demonstrated that the crystalline phases of PP in the composites were changed and that the β phase significantly increased. An examination of the electrical properties revealed that the direct-current (dc) electric breakdown strength and space-charge suppression effect were remarkably improved by the introduction of the surface-modified MgO nanoparticles. In addition, obvious enhancements in the tensile modulus and strength were obtained as a result of the synergistic toughening of the POE and MgO nanoparticles. Thus, MgO/PP/POE nanocomposites with enhanced mechanical and electrical properties have great potential to be used as recyclable insulation materials for high-voltage dc cables with large transmission capacities and high operating temperatures. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 132, 42863.

Hybrid carrageenan‐based formulations for edible film preparation: Benchmarking with kappa carrageenan

Abstract: An intense search for new renewable sources to produce natural polymers for edible and biodegradable packaging is observed as they offer lower environmental costs. The objective of this work is to investigate the use of hybrid carrageenan, extracted from Mastocarpus stellatus seaweeds, as an alternative to commercial kappa carrageenan in new edible film formulations. To this end, the production and characterization of biodegradable films obtained with mixtures of rice starch and hybrid carrageenan or commercial kappa carrageenan were carried out. Thin, flexible, and transparent films with attractive functional properties were obtained from rice starch–carrageenan mixtures. Films forming solutions produced with hybrid carrageenan showed rheological properties comparable to commercial kappa carrageenan-based solutions. Films formulated with hybrid carrageenan show significantly enhanced UV barrier, oxygen barrier, and hydrophobic properties. Thus, hybrid carrageenan proved to be a promising material for the production of edible coatings and biodegradable films and a good alternative to kappa carrageenan for such application. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42263.

Preparation and characterization of poly(ethylene glycol) stabilized nano silver particles by a mechanochemical assisted ball mill process

Abstract: Nano silver particles with an average mean crystallite size of between 10 and 12 nm were synthesized from different molecular weights of poly(ethylene glycol) as a stabilizing agents, through solid state oxidation of silver nitrate using a higher energy planetary ball mill. Ultraviolet-Visible spectra were used to confirm the synthesis of nano silver particles. The surface plasmon resonance bands were observed around 410 nm. Fourier transformed infrared spectrum, X-ray diffraction, and transmission electronic microscopy techniques were used to characterize the nano silver particles synthesized. Thermal stability was determined using thermogravimetic analysis and the elemental composition of the sample was determined by energy dispersive X-ray analysis. The nano silver particles synthesized, exhibited very good antibacterial activity against Gram-positive bacteria (Bacillus) and Gram-negative bacteria (Pseudomonas aeruginosa). Based on the obtained results, it was additionally explored that the size and the stabilization of the nano silver particles synthesized, strongly depend on the molecular weight of poly(ethylene glycol). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43027.

Evaluation of some eco-friendly plasticizers for PLA films processing

Abstract: This study was conducted as a first step in order to obtain green materials for food packaging by using an eco-friendly bioplastic, polylactic acid (PLA), and nontoxic plasticizers. Different types of nontoxic biocompatible plasticizers/lubricants, both obtained in the laboratory, as well as commercial ones, were employed to modulate physical and mechanical properties of PLA. Melt compounding by means of a Brabender mixer led to obtaining of homogeneous materials. The incorporation of PLA oligomer, l-lactide, poly(ethylene glycol), and epoxidized soybean oil (USE) improved the melt flow and processability, increasing the hydrophilicity of the resulted plasticized PLA systems. USE significantly increased the elongation at break, reduced the glass transition temperature, and increased the PLA chain mobility. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43223.

Synergistic effect of lactic acid oligomers and laminar graphene sheets on the barrier properties of polylactide nanocomposites obtained by the in situ polymerization pre‐incorporation method

Abstract: J. Ambrosio-Martin would like to thank the Spanish Ministry ofEconomy and Competitiveness for the FPI grant BES-2010–038203. M.J. Fabra is recipient of a “Juan de la Cierva” contractfrom the Spanish Ministry of Economy and Competitiveness. Theauthors acknowledge financial support from the MINECO(MAT2012–38947-C02-01 project) and from the FP7 ECOBIO-CAP project.

Interfacial mechanical behavior of 3D printed ABS

Abstract: We describe an experimental approach for characterizing the local mechanical behavior of acrylonitrile butadiene styrene (ABS) structures processed through fused deposition modeling. ABS test specimens processed in various build orientations were subject to multiscale mechanical tests as well as local morphology and chemical analyses. Instrumented indentation, local dynamic mechanical analysis, and atomic force microscopy tests were used to explore the mechanical behavior and morphology of build surfaces and weld interfaces. An interfacial stiffening effect was found for the majority of the specimens tested, with up to a 40% increase in the indentation elastic modulus measured with respect to the build surfaces. Raman spectroscopy mapping of the interfacial areas revealed ∼30% less butadiene/styrene and butadiene/acrylonitrile ratios with respect to analysis of the build surfaces. The results provide insight into the multiscale behavior of additive manufactured structures and offer the potential to guide processing–structure–property understanding of these materials. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43671.

A comparison of partially acetylated nanocellulose, nanocrystalline cellulose, and nanoclay as fillers for high‐performance polylactide nanocomposites

Abstract: Partially acetylated cellulose nanofibers (CNF) were chemically extracted from sisal fibers and the performance of those CNF as nanofillers for polylactide (PLA) for food packaging applications was evaluated. Three PLA nanocomposites; PLA/CNF (cellulose nanofibers), PLA/CNC (nanocrystalline cellulose), and PLA/C30B (CloisiteTM 30B, an organically modified montmorillonite clay) were prepared and their properties were evaluated. It was found that CNF reinforced composites showed a larger decrease on oxygen transmission rate (OTR) than the clay-based composites; (PLA/CNF 1% nanocomposite showed a 63% of reduction at 23°C and 50% RH while PLA/C30B 1% showed a 26% decrease) and similar behavior on terms of water vapor barrier properties with 46 and 43%, respectively of decrease on water vapor transmission rate at 23°C and 50% RH (relative humidity). In terms of mechanical and thermomechanical properties, CNF-based nanocomposites showed better performance than clay-based composites without affecting significantly the optical transparency. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43257.

Influence of citric acid on the properties and stability of starch‐polycaprolactone based films

Abstract: The influence of citric acid (CA) on structural and physicochemical properties of blend films based on corn starch and polycaprolactone (PCL) was studied. Films were obtained by melt blending of starch and PCL and compression molding. Phase separation of polymers observed by scanning electron microscope and atomic force microscope was reduced by CA incorporation. CA affected both starch and PCL crystallization as deduced from the X-ray diffraction patterns and values of melting enthalpy. Glass transition of starch was reduced by PCL incorporation, while this occurred to a greater extent in films containing CA. Obtained results point to enhanced interactions between PCL and starch chains in films with CA, although this only quantitatively benefits the film properties at a low PCL ratio. Compounding starch with small amounts of PCL, using glycerol and CA, can supply films with better functional properties than net starch films. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42220.

Solution blowing of thermoplastic polyurethane nanofibers: A facile method to produce flexible porous materials

Abstract: Solution blowing (SB) is a promising and scalable approach for the production of nanofibers. Air pressure, solution flow-rate, and nozzle-collector distance were determined as effective process parameters, while solution concentration was also reported as a material parameter. Here we performed a parametric study on thermoplastic polyurethane/dimethyl formamide (TPU/DMF) solutions to examine the effect of such parameters on the resultant properties such as fiber diameter, diameter distribution, porosity, and air permeability of the nanofibrous webs. The obtained solution blown thermoplastic polyurethane (TPU) nanofibers had average diameter down to 170 ± 112 nm, which is similar to that observed in electrospinning. However, the production rate per nozzle can be 20 times larger, which is primarily dependent on air pressure and solution flow rate (20 mL/h). Moreover, it was even possible to produce nanofibers polymer concentrations of 20%; however, this increased the average nanofiber diameter. The fibers produced from the TPU/DMF solutions at concentrations of 20% and 10% had average diameters of 671 ± 136 nm and 170 ± 112 nm, respectively. SB can potentially be used for the industrial-scale production of products such as nanofibrous filters, protective textiles, scaffolds, wound dressings, and battery components. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43025.

Morphology and dynamical mechanical properties of poly ether ketone ketone (PEKK) with meta phenyl links

Abstract: Poly ether ketone ketone (PEKK) with different proportion of meta phenyl links were investigated by combining differential scanning calorimetry and dynamic mechanical analysis. The influence of the Terephthalyl/Isophthalyl isomers (T/I) ratio on the vitreous phase is mild, the shift of the glass transition is limited to a few degrees and the vitreous G0 is only sensitive to the content of the crystalline phase. Contrarily, the increase of meta isomers is responsible for a significant decrease of the melting temperature (Tm) by 60 8C, which considerably facilitates processing. The modification of interchain interactions in the crystalline phase might be implied. A series of thermal protocols evidenced that the difference of crystallization behavior is also dependent upon the T/I isomer ratio. A time and temperature dependence of annealing on the double melting behavior of PEKK was observed. Regarding the mechanical behavior, the observed reinforcing effect due to the crystalline phase was more prominent in the rubbery state than in the glassy state.

Poly(l‐lactide)/zno nanocomposites as efficient UV‐shielding coatings for packaging applications

Abstract: Poly(l-lactide) (PLLA)/ZnO nanocomposites have been developed as efficient UV-shielding coatings for packaging applications. ZnO have been selected as the most suitable UV-shielding material over 10 different metallic nanoparticles. Results reveal a nucleating effect of ZnO in which PLLA crystallization half time is reduced from 7.4 to 4.7 min with only 0.05 wt % ZnO. UV–vis spectroscopy confirms the UV-shielding effect in PLLA/ZnO nanocomposites, where the ultraviolet spectrum is blocked by 61.2% for a concentration as low as 0.45 vol %, while the 95.9% of the visible radiation passes through the material. A schematic representation explaining obtained UV-shielding effect is constructed based on the photon mean free path reduction as ZnO concentration increases. Water contact angle increased from 81° up to 91° for the 5 wt % nanocomposite, which would result beneficial in view to develop materials for packaging applications. Dynamic mechanical analysis exhibits a Tg increase with nanoparticle loading arising from the chain confinement caused by the presence of ZnO interacting surfaces. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42426.

Characterization and properties of LDPE film with gallic‐acid‐based oxygen scavenging system useful as a functional packaging material

Abstract: We prepared and characterized active, oxygen-scavenging, low density polyethylene (LDPE) films from a non-metallic-based oxygen scavenging system (OSS) containing 1, 3, 5, 10, and 20% of gallic acid (GA) and potassium chloride (PC). We compared the surface morphology and mechanical, permeability, and optical properties of the oxygen-scavenging LDPE film with those of pure LDPE film. The surface morphology, gas barrier, and thermal properties indicate that the OSS was well incorporated into the LDPE film structure. The surface roughness of the film increased with the amount of oxygen scavenging material. The oxygen and water vapor permeability of the developed film also increased with the amount of oxygen scavenging material, though its elongation decreased. The oxygen scavenging capability of the prepared film was analyzed at different temperatures. The initial oxygen content (%) in the vial headspace, 20.90%, decreased to 16.6% at 4 °C, 14.6% at 23 °C, and 12.7% at 50 °C after 7 days of storage with the film containing 20% OSS. The film impregnated with 20% organic oxygen scavenging material showed an effective oxygen scavenging capacity of 0.709 mL/cm2 at 23 °C. Relative humidity triggered the oxygen scavenging reaction. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44138.

Production of bacterial nanocellulose from wine industry residues: Importance of fermentation time on pellicle characteristics

Abstract: Fil: Cerrutti, Patricia. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Houssay. Instituto de Tecnologia En Polimeros y Nanotecnologia. Universidad de Buenos Aires. Facultad de Ingenieria. Instituto de Tecnologia En Polimeros y Nanotecnologia; Argentina

Interfacial evaluation of epoxy/carbon nanofiber nanocomposite reinforced with glycidyl methacrylate treated UHMWPE fiber

Abstract: Interface interactions of fiber–matrix play a crucial role in final performance of polymer composites. Herein, in situ polymerization of glycidyl methacrylate (GMA) on the ultrahigh molecular weight polyethylene (UHMWPE) fibers surface was proposed for improving the surface activity and adhesion property of UHMWPE fibers towards carbon nanofibers (CNF)-epoxy nanocomposites. Chemical treatment of UHMWPE fibers was characterized by FTIR, XPS analysis, SEM, and microdroplet tests, confirming that the grafting of poly (GMA) chains on the surface alongside a significant synergy in the interfacial properties. SEM evaluations also exhibited cohesive type of failure for the samples when both GMA-treated UHMWPE fiber and CNF were used to reinforce epoxy matrix. Compared with unmodified composite, a ∼319% increase in interfacial shear strength was observed for the samples reinforced with both 5 wt % GMA-grafted UHMWPE and 0.5 wt % of CNF. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43751.

Inkjet printing of polyimide insulators for the 3D printing of dielectric materials for microelectronic applications

Abstract: In this article, we report the first continuous fabrication of inkjet-printed polyimide films, which were used as insulating layers for the production of capacitors. The polyimide ink was prepared from its precursor poly(amic) acid, and directly printed on to a hot substrate (at around 160 °C) to initialize a rapid thermal imidization. By carefully adjusting the substrate temperature, droplet spacing, droplet velocity, and other printing parameters, polyimide films with good surface morphologies were printed between two conducting layers to fabricate capacitors. In this work, the highest capacitance value, 2.82 ± 0.64 nF, was achieved by capacitors (10 mm × 10 mm) with polyimide insulating layers thinner than 1 μm, suggesting that the polyimide inkjet printing approach is an efficient way for producing dielectric components of microelectronic devices. © 2016 The Authors Journal of Applied Polymer Science Published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43361.

ForceSpinning of polyacrylonitrile for mass production of lithium‐ion battery separators

Abstract: We present results on the Forcespinning® (FS) of Polyacrylonitrile (PAN) for mass production of polymer nanofiber membranes as separators for Lithium-ion batteries (LIBs). Our results presented here show that uniform, highly fibrous mats from PAN produced using Forcespinning®, exhibit improved electrochemical properties such as electrolyte uptake, low interfacial resistance, high oxidation limit, high ionic conductivity, and good cycling performance when used in lithium ion batteries compared to commercial PP separator materials. This article introduces ForceSpinning®, a cost effective technique capable of mass producing high quality fibrous mats, which is completely different technology than the commonly used in-house centrifugal method. This Forcespinning® technology is thus the beginning of the nano/micro fiber revolution in large scale production for battery separator application. This is the first time to report results on the cycle performance of LIB-based polymer nanofiber separators made by Forcespinning® technology. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 132, 42847.

Producing high-quality precursor polymer and fibers to achieve theoretical strength in carbon fibers: A review

Abstract: The precursor fiber quality has a large impact on carbon fiber processing in terms of its performance, production yield, and cost. Polyacrylonitrile precursor fibers have been used commercially to produce strong carbon fibers with average tensile strength of 6.6 GPa. There is a scope to improve the average tensile strength of carbon fibers, since only 10% of their theoretical strength has been achieved thus far. Most attempts to increase the tensile strength of carbon fibers have been made during the conversion of precursor fiber to carbon fiber. This review highlights the potential opportunities to enhance the quality of the polyacrylonitrile-based precursor fiber during polymer synthesis, spinning, and postspinning. These high-quality precursor fibers can lead to new generation carbon fibers with improved tensile strength for high-performance applications. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43963.

Influence of fiber orientation and fiber content on properties of sisal‐jute‐glass fiber‐reinforced polyester composites

Abstract: The incorporation of natural fibers with polymer matrix composites (PMCs) has increasing applications in many fields of engineering due to the growing concerns regarding the environmental impact and energy crisis. The objective of this work is to examine the effect of fiber orientation and fiber content on properties of sisal-jute-glass fiber-reinforced polyester composites. In this experimental study, sisal-jute-glass fiber-reinforced polyester composites are prepared with fiber orientations of 0° and 90° and fiber volume of sisal-jute-glass fibers are in the ratio of 40:0:60, 0:40:60, and 20:20:60 respectively, and the experiments were conducted. The results indicated that the hybrid composites had shown better performance and the fiber orientation and fiber content play major role in strength and water absorption properties. The morphological properties, internal structure, cracks, and fiber pull out of the fractured specimen during testing are also investigated by using scanning electron microscopy (SEM) analysis. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42968.