pinecone/core-2020-05-10-deduplication huggingface dataset:
Development of nanofiber-reinforced hydrogel scaffolds for nucleus pulposus regeneration by a combination of electrospinning and spraying technique

In this work a new method is presented to efficiently produce hydrogel scaffolds reinforced with nanofibers to show
enhanced mechanical properties and improved structural integrity. The method is based on a combination of air brush spraying of a
hydrogel and electrospinning of nanofibers. With air brush spraying the controllability is enhanced and the potential for scale-up
increased. The developed method was used to successfully reinforce gellan gum hydrogels with electrospun polycaprolactone nanofibers.
Optical and rheological evaluations were performed and showed that parameters such as the amount of incorporated nanofibers,
gellan gum concentration and calcium chloride (crosslinker) concentrations could be used to modulate material properties. Incorporation
of a small amount of nanofibers had a reinforcing effect and resulted in a hydrogel with rheological properties similar to the
human nucleus pulposus (NP). The method is flexible and carries potential for designing scaffolds for e.g. NP tissue regeneration.The authors gratefully acknowledge funding from the Disc Regeneration Project (grant agreement number: NMP-LA-2008-213904) from the European Community. Also, they acknowledge RISE Research Institutes of Sweden Holding AB for financial support of this study
Functionalization of wool fabric with phase-change materials microcapsules after plasma surface modification

The use of microcapsules has increased in several different areas, namely, textile applications. They have been used as a possible means of introducing new properties, namely, in medical care by antibiotics, skin moisturizers, and other drugs and for thermal comfort. In this study, we examined the influence of dielectric barrier discharge (DBD) plasma treatment on the adhesion of phase-change material (PCM) microcapsules on wool fabric. Several experimental techniques were used to evaluate the wool surface modification after plasma treatment and the influence of the microcapsules' resistance to washing conditions, namely, the determination of the static and dynamic contact angles, surface energy, and adhesion work; X-ray photoelectron spectroscopy; Fourier transform infrared spectroscopy; differential scanning calorimetry; and scanning electron microscopy. Chemical and physical characterization of the wool fiber in the fabric confirmed significant surface modification. The plasma treatment greatly increased the hydrophilicity, surface energy, and adhesion work of the wool fabric; this proved that more microcapsules were adsorbed on the fabric and more microcapsules remained on the fabric surface after the washing procedures.Fundação para a Ciência e a Tecnologia (FCT
Synthesis and characterization of organic/inorganic epoxy nanocomposites from poly(aminopropyl/phenyl)silsesquioxanes

Organic/inorganic epoxy nanocomposites containing diglycidyl ether of bisphenol A (DGEBA), 4‐methylhexahydrophthalic anhydride (MHHPA) and poly(aminopropyl/phenyl) silsesquioxanes (PAPPS) were prepared and characterized. PAPPS were synthesized via fluoride‐catalyzed cage formation from random‐structured poly(phenyl)silsesquioxane (PPS) and 3‐aminopropyltriethoxysilane (APTES) in tetrahydrofuran (THF) using tetrabutylammonium fluoride (TBAF) catalyst containing substantial water. The PPS/APTES stoichiometric ratios were varied. The FTIR,  1 H, solid‐state  29 Si‐NMR studies show that PAPPS probably consists of cages, partial cages, and some linear structures containing phenyl and aminopropyl functional groups. The amine content was determined by back titration and elemental analysis. In comparison with neat epoxy, incorporation of these materials can improve the resultant thermal stabilities, raise glass transition temperatures ( T  g s), and reduce coefficients of thermal expansion (CTEs) of epoxy nanocomposites as confirmed by TG/DTA, DMA and TMA tests, respectively. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 201
Chitosan gel film bandages: correlating structure, composition, and antimicrobial properties

Chitosan gel films were successfully obtained by evaporation cast from chitosan solutions in aqueous acidic solutions of organic acids (lactic and acetic acid) as gel film bandages, with a range of additives that directly influence film morphology and porosity. We show that the structure and composition of a wide range of 128 thin gel films, is correlated to the antimicrobial properties, their biocompatibility and resistance to biodegradation. Infrared spectroscopy and solid-state 13C nuclear magnetic resonance spectroscopy was used to correlate film molecular structure and composition to good antimicrobial properties against 10 of the most prevalent Gram positive and Gram negative bacteria. Chitosan gel films reduce the number of colonies after 24 h of incubation by factors of ∼105–107 CFU/mL, compared with controls. For each of these films, the structure and preparation condition has a direct relationship to antimicrobial activity and effectiveness. These gel film bandages also show excellent stability against biodegradation with lysozyme under physiological conditions (5% weight loss over a period of 1 month, 2% in the first week), allowing use during the entire healing process. These chitosan thin films and subsequent derivatives hold potential as low-cost, dissolvable bandages, or second skin, with antimicrobial properties that prohibit the most relevant intrahospital bacteria that infest burn injuries
Enhanced adhesion of polypyrrole/PW12O40 3- hybrid coatings on polyester fabrics

Polyester fabrics have been treated with plasma to increase polypyrrole/PW12O40 3- (hybrid material) adhesion to its surface. With the plasma treatment, the roughness of the fibers increases as it has been observed by means of atomic force microscopy (AFM). Polar functional groups are also created on the surface of polyester fabrics as X-ray photoelectron spectroscopy (XPS) measurements have shown. These polar groups contribute to the adhesion of polypyrrole to the fibers. Coatings obtained on plasma treated fabrics were more resistant to washing and rubbing fastness tests. The use of an inorganic counter ion (PW12O 403-) that contains an element with a high atomic number (W) helps to locate zones where the coating is missed; this is achieved by means of micrographs obtained by backscattered electrons (BSE). The electrical resistance of the fabrics was also measured by electrochemical impedance spectroscopy (EIS), obtaining also better results with the plasma treated fabrics. Copyright © 2012 Wiley Periodicals, Inc.Authors thank to the Spanish Ministerio de Ciencia e Innovación (contracts CTM2010-18842-C02-02 and CTM2011-23583) and Universitat Politècnica de València (Primeros Proyectos de Investigación (PAID-06-10)) for the financial support. J. Molina is grateful to the Conselleria d'Educació (Generalitat Valenciana) for the FPI fellowship
Microencapsulation of imidazole curing agent by solvent evaporation method using W/O/W emulsion

The epoxy–imidazole resin system is used to form the anisotropic conducting film. The latent character of the system is very significant. In this study, imidazole (Im) or 2‐methylimidazole (2MI) was encapsulated for the latent curing system to use in the reaction of epoxy resin. Polycaprolactone was used as a wall material, and the solvent evaporation method was used to form the microcapsule using W/O/W emulsion. The shelf life of the microcapsules was studied for the epoxy resin, and the curing behavior of the microcapsules for epoxy resin was examined using a differential scanning calorimeter. The curing times at 150 and 180°C were estimated using an indentation method. The microcapsules of Im or 2MI exhibited a long shelf life for epoxy resin. When comparing the results of the previous methods with the results of this study using the W/O/W emulsion, finer microcapsules were formed and the microcapsule has longer shelf life. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 201
Mechanical behavior, microstructure and thermooxidation properties of sequentially crosslinked ultrahigh molecular weight polyethylenes

The aim of this study was to explore the impact of the sequential irradiation and annealing process on the microstructure, thermooxidation behavior and mechanical properties of GUR 1050 ultrahigh molecular weight polyethylene (UHMWPE) with respect to the postirradiation annealed material. For this purpose, the effects of a variety of irradiation and annealing conditions on microstructure and mechanical properties were investigated. Differential scanning calorimetry was performed to characterize melting temperature, crystalline content and crystal thickness, whereas transmission electron microscopy provided additional insights into crystal morphology. Thermogravimetric experiments in air served to assess thermooxidation resistance and changes associated to radiation-induced crosslinking. Fatigue properties were studied from three different approaches, namely short-term cyclic stress–strain tests, long-term fatigue experiments and crack propagation behavior. Likewise, three experimental techniques (uniaxial tensile test, impact experiments, and load to fracture of compact tension specimens) allowed evaluation of the fracture resistance. The present findings confirm sequentially crosslinked UHMWPE exhibited improved thermooxidation resistance and thermal stability compared to post-irradiation annealed UHMWPE. Also, the mechanical behavior, including the fatigue and fracture resistance, of these materials was generally comparable regardless of the annealing strategy. Therefore, the sequential irradiation and annealing process might provide higher oxidation resistance, but not a significant improvement in mechanical properties compared to the single radiation dose and subsequent annealing procedure.Research funded by the Comisi on Interministerial de Ciencia y Tecnología (CICYT), Spain. Project: MAT 2006-12603-C02-01.Peer reviewe
Essential work of fracture of poly(ϵ-caprolactone)/boehmite alumina nanocomposites: Effect of surface coating

The essential work of fracture (EWF) approach has been adopted to reveal the effect of nanofillers on the\ud
toughness of poly(ε-caprolactone)/boehmite alumina (PCL/BA) nanocomposites. Synthetic BA particles\ud
of different surface treatments were dispersed in the PCL matrix by extrusion melt compounding. The\ud
morphology of composites was studied by scanning electron microscopy. Differential scanning\ud
calorimetry and wide angle X-ray scattering were used to detect changes in the crystalline structure of\ud
PCL. Besides the mode I type EWF tests, dynamic mechanical analysis (DMA) and quasi-static tensile\ud
tests were applied to study the effect of BA nanofillers on the mechanical properties. BA was\ud
homogenously dispersed and acted as heterogeneous crystallization nucleant and non-reinforcing filler in\ud
PCL. The tensile modulus and yield strength slightly increased, whereas the yield strain decreased with\ud
increasing BA content (up to 10 wt%). Effect of the BA surface treatment with octylsilane (OS) was\ud
negligible by contrast to alkylbenzene sulphonic acid (OS2). Like the tensile mechanical data, the\ud
essential and non-essential work of fracture parameters did not change significantly, either. Improved\ud
PCL/BA adhesion in case of OS2 treatment excluded the usual EWF treatise. This was circumvented by\ud
making use of energy partitioning between yielding and necking. The yielding related essential work of\ud
fracture decreased while the non-essential one increased with BA content and with better interfacial\ud
adhesion. This was attributed to the effect of matrix/filler debonding
Crystallization behavior of poly(lactide)/poly(β-hydroxybutyrate)/talc composites.

The authors thank Dr. Patrice Lefrançois (CNAM) for SEM observations. They are also grateful to Pr. Jack R. Plimmer USDA, Agricultural Research Service, USA for his discussions during this work.The morphology and miscibility of commercial poly(lactide) (PLA)/poly(b-hydroxybutyrate) (PHB, from 5 to 20 wt %) blends prepared by melt extrusion method, were investigated using differential scanning calorimetry (DSC) and Fourier transform infra-red spectroscopy (FTIR) observations. The results show that for all the studied blend contents, PLA/PHB blends are immiscible. The effects of PHB and talc on the nonisothermal cold crystallization kinetics of PLA were examined using a differential scanning calorimetry (DSC) at different heating rates. PHB acted as a nucleating agent on PLA and the addition of talc to the blend yielded further improve-ment, since significant increase in the enthalpy peak was observed for samples containing 10 wt % PHB and talc (from 0.5 to 5 phr). The crystallization kinetics were then examined using the Avrami–Jeziorny and Liu–Mo approach. The simultaneous presence of PHB and talc induced a decrease of the crystallization half time. The evolution of activation energies determined with Kissinger’s equation suggests that blending with PHB and incorporating talc promote nonisothermal cold crystallization of PLA. The synergistic nucleating effect of PHB and talc was also observed on isothermal crystallization of PLA from the melt
The water vapor sorption behavior of a galactomannan cellulose nanocomposite film analyzed using parallel exponential kinetics and the Kelvin–Voigt viscoelastic model

Nanocomposite films have been developed where a galactomannan (guar) matrix was reinforced with cellulose nanowhiskers and plasticized using sorbitol. The properties of these films were compared with films made from guar only. The films were examined using scanning electron microscopy and dynamic vapor sorption. The sorption kinetics properties were analyzed using parallel exponential kinetics (PEK) and this data interpreted using the Kelvin-Voigt (K-V) viscoelastic model. Substantial differences in sorption behavior were noted between the guar and cellulose reinforced guar films. Addition of cellulose nanowhiskers (CNWs) to the guar resulted in a change in the shape of the isotherm, as well as a reduced equilibrium moisture content throughout the hygroscopic range. With the guar film, hysteresis between the adsorption and desorption branches of the isotherm occurred up to 75% RH, where it collapsed. Dynamic mechanical analysis showed that the collapse of the hysteresis loop occurred at the glass transition temperature of the guar film. However, addition of CNWs to the guar produced a film where sorption hysteresis was found to occur throughout the hygroscopic range. The applicability of the K-V interpretation of the sorption kinetics is discussed
Isothermal crystallization kinetics and mechanical properties of polycaprolactone composites with zinc oxide, oleic acid, and glycerol monooleate

The isothermal crystallization and mechanical behavior of polycaprolactone (PCL) with zinc oxide (ZnO) with oleic acid and glycerol monooleate (GMO) were studied. Theoretical melting points calculated by the Flory-Huggins and Thompson-Gibbs models were thoroughly compared with differential scanning calorimetry experimental observations. The isothermal crystallization kinetic parameters by Avrami analysis showed that crystallization was controlled by nucleation, crystal growth was spherical, and the nucleation type changed between thermal and athermal nucleation. X-ray diffraction showed that when the additives were used together both the crystal thickness and the degree of crystallinity increased. A multiple-response regression analysis was made with the ZnO, oleic acid, and GMO concentrations as variables and the crystallinity as output. Interaction parameters by the Pukanzky model were calculated from the tensile strength at the yield point and indicated that the addition of oleic acid or GMO improved the interface between the ZnO particles and PCL.TUBITAK-110M157; Ege University Scientific Research Project Fund (BAP 09/MUH/093
Water, salt water and alkaline solution uptake in epoxy thin films

As a means of characterizing the diffusion parameters of fiber reinforced polymer (FRP) composites within a relatively short time frame, the potential use of short term tests on epoxy films to predict the long-term behavior is investigated. Reference is made to the literature to assess the effectiveness of Fickian and anomalous diffusion models to describe solution uptake in epoxies. The influence of differing exposure conditions on the diffusion in epoxies, in particular the effect of solution type and temperature, are explored. Experimental results, where the solution uptake in desiccated (D) or undesiccated (U) thin films of a commercially available epoxy matrix subjected to water (W), salt water (SW), or alkali concrete pore solution (CPS) at either 20 or 60°C, are also presented. It was found that the type of solution did not significantly influence the diffusion behavior at 20°C and that the mass uptake profile was anomalous. Exposure to 60°C accelerated the initial diffusion behavior and appeared to raise the level of saturation. In spite of the accelerated approach, conclusive values of uptake at saturation remained elusive even at an exposure period of 5 years. This finding questions the viability of using short-term thin film results to predict the long-term mechanical performance of FRP materialsThe first author was funded through an Engingeering and Physical Science Research Council Doctoral Training Award.This is the peer reviewed version of Scott, P. and Lees, J.M. (2013) Water, salt water and alkaline solution uptake in epoxy thin films, Journal of Applied Polymer Science, v. 130 (3) pp. 1898-1908 which has been published on: http://dx.doi.org/10.1002/app.39331. © 2013 Wiley Periodicals, Inc
Effects of particle size and electrical resistivity of filler on mechanical, electrical, and thermal properties of linear low density polyethylene-zinc oxide composites

The effects of particle size and electrical resistivity of zinc oxide (ZnO) on mechanical properties, electrical and thermal conductivities of composites made with linear low density polyethylene (LLDPE) were investigated. Micron sized (mZnO), submicron sized (sZnO), and nano sized (nZnO) powders having resistivities of 1.5 × 106, 1.5 × 109, and 1.7 × 108 were used to prepare composites with 5-20 vol % filler. The tensile strength was lowered and the modulus of elasticity of the composites was increased with ZnO addition. Rather than the particle size of the ZnO, its initial resistivity and aspect ratio affected the resistivity of composites. The resistivity of the LLDPE was lowered from 2.3 × 1016 Ω cm down to 1.4 × 1010 Ω cm with mZnO addition. Thermal conductivity of the composites was increased with ZnO addition 2.5-3 times of the polymer matrix. The composites can be used for electrostatically dissipating and heat sink applications due to their decreased electrical resistivity and increased thermal conductivity.IYTE BAP 2006 IYTE 2
Effect of molecular architecture on the crystalline structure and stiffness of iPP homopolymers: modeling based on annealing experiments

Five PP homopolymers were selected and their molecular structure was thoroughly characterized to determine the effect of molecular architecture on their annealing behavior and on the ultimate stiffness achieved by heat treatment. Molecular mass and its distribution were characterized by rheological measurements, while chain regularity was determined by calorimetry, by the stepwise isothermal segregation technique (SIST). The samples were annealed in two different ways. Tensile bars were treated in an oven at 165 °C for increasing times to determine changes in stiffness. Various defects developed during the annealing of tensile specimens that did not allow the reliable determination of modulus by direct measurement. On the other hand, the second approach, the annealing of small samples in a DSC cell clearly showed the changes occurring in crystalline structure and also the effect of nucleation and molecular architecture on them. The large molecular weight fraction used to facilitate nucleation hinders crystal perfection, while the presence of a heterogeneous nucleating agent increases overall crystallinity, but does not influence recrystallization during annealing. Melting traces were transformed into lamella thickness distributions, from which average lamella thickness was derived. Lamella thickness and crystallinity, the independent variables of the empirical equation used for the calculation of modulus, were extrapolated to infinite annealing time to predict maximum stiffness. The value obtained, 3.5 GPa, is very far from the theoretically predicted 40 GPa of oriented crystals, which cannot be achieved under practical conditions
PLA/Lignocellulosic fiber composites: particle characteristics, interfacial adhesion and failure mechanism.

PLA composites were prepared using six lignocellulosic fibers with widely varying particle characteristics. The composites were characterized by tensile testing, scanning electron (SEM) and polarization optical (POM) microscopy. Micromechanical deformation processes during loading were followed by acoustic emission measurements. Interfacial adhesion was estimated by three independent methods. Contrary to most claims published in the literature, interfacial adhesion between PLA and natural fibers was found to be rather strong, a result confirmed by the quantitative estimation of adhesion strength, acoustic emission measurements and SEM study. Strong interfacial adhesion results in weak dependence of the extent of reinforcement on the particle characteristics of the reinforcing fibers. Both acoustic emission measurements and microscopy indicated that the dominating micromechanical deformation process is the fracture of the fibers and close correlation was found between the initiation stress of fiber fracture, reinforcement and the ultimate strength of the composites
A new method to predict optimum cure time of rubber compound using dynamic mechanical analysis

The degree of vulcanization of a rubber compound has a big influence on the properties of the final product. Therefore, precisely defining the curing process including optimum cure time is important to ensure the production of final products having high performance. Typically, vulcanization is represented using vulcanization curves. The main types of equipment used for producing vulcanization curves are the oscillating disc rheometer (ODR) and the moving die rheometer (MDR). These can be used to plot graphs of torque versus time at a constant temperature to show how cure is proceeding. Based on the results obtained, optimum cure time (t₉₀) is calculated as the time required for the torque to reach 90% of the maximum achievable torque. In this study, the use of Dynamic Mechanical Analysis (DMA) for assessment of t₉₀ was assessed. DMA was carried out using shear mode isothermal tests to measure the changes in material properties caused by vulcanization. The results revealed that the shear storage modulus (G′), shear loss modulus (G′′), and tan δ all reflect the vulcanization process, however, tan δ gave the best representation of level of vulcanization. Indeed, the curve of tan δ was able to be used to derive the t₉₀ for rubber compounds and showed good agreement with the results from an MDR