pinecone/core-2020-05-10-deduplication huggingface dataset:
Preparation and properties of polyamide-6-based thermoplastic laminate composites by a novel in-mold polymerization technique

In this work, a method for preparation of polyamide-6 (PA6) based laminates reinforced by glass fiber- (GFL) or
polyamide-66 (PA66) textile structures (PL) via reactive injection molding is disclosed. It is based on in-mold anionic polymerization of eps-caprolactam carried out at 165º C in the presence of the respective reinforcements performed in newly developed prototype equipment whose design concept and operation are described. Both composite types were produced for reaction times of 20 min, with conversion degrees of 97–99%. Initial mechanical tests in tension of GFL samples displayed almost twofold increase of the Young’s modulus and stress at break values when compared with the neat anionic PA6. The improvement was proportional to the
volume fraction Vf of glass fiber fabric that was varied in the 0.16–0.25 range. A 300% growth of the impact strength was registered in PL composites with Vf of PA66 textile of 0.1. Removing the surface finish of the latter was found to be a factor for improving the adhesion at the matrix–fiber interface. The mechanical behavior of GFL and PL composites was discussed in conjunction with the morphology of the samples studied by optical and electron microscopy and the matrix crystalline structure as revealed by synchrotron X-ray diffraction.Fundação para a Ciência e Tecnologia; German Synchrotron Radiation Source - DESY, Hambur
Investigations on Rheological Properties and Gelation of Tasar Regenerated Silk Fibroin Solution

Tasar silk is a variety of non-mulberry silk indigenous to the Indian subcontinent. We present the measured frequency-dependent viscoelastic moduli of Tasar regenerated silk fibroin (RSF) solution using optical tweezers at two concentrations (0.16% and 0.25% w/v) and extend these measurements to the low frequency regime using a video microscopy technique. We extend the investigation on the rheological behavior of Tasar RSF for four more RSF concentrations, viz., 0.50%, 1.00%, 2.50% and 5.00% using video microscopy. In all the RSF samples, both storage and loss moduli are found to increase with frequency. At lower frequencies the loss modulus is more than the storage modulus and exhibit similar behavior until a crossover frequency beyond which the storage modulus exceeds the loss modulus at all frequencies. The relaxation time which is inversely related to the crossover frequency is found to rise sharply at 5% w/v, indicating the onset of gelation in the sample. These results are examined in relation to the viscoelastic parameters of mulberry silk, wherein the larger crossover frequencies at the same higher concentrations indicate relaxation times that are an order of magnitude smaller than those measured for Tasar RSF. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 4010
Negative differential conductance materials for flexible electronics

The need for electronics that is compatible with life is driving the search for electronically active materials that may be used for transferring integrated circuits onto flexible substrates. One route is to build transistors, which modulate the conductivity of organic thin films with a lateral gate. However, as is well known in the case of graphene, the in-plane conductivity cannot easily be switched off. Another route is to use negative differential resistance (NDR) phenomena. Until recently, NDR was only obtained from band engineered semiconductors. This article reviews the recent development of flexible materials that specifically make use of transport perpendicular to graphite planes to obtain NDR. These materials include h-boron-nitride/graphene multilayers and graphite-silicone composites. We report on the dependence of their current-voltage curves on deformation, changes in structural and experimental parameters. We also describe device implementations in the form of flexible oscillators, amplifiers and memories
Microneedles from fish scale biopolymer

This article was published in the serial Journal of Applied Polymer Science [© Wiley Periodicals, Inc.]. The definitive version is available at: http://dx.doi.org/10.1002/app.40377This article reports on microneedles produced from biopolymer films extracted from fish scales of tilapia (Oreochromiss sp.) using micromolding technique. Evaluation of the properties of polypeptide films prepared from the fish scales gave refractive index (1.34), protein concentration (78%), ash content (1.6%) at (22%) moisture content. The microneedles successfully inserted into artificial skin models and imaging using digital camera showed microneedles remained intact when inserted and when removed from the skin model. Microneedles also successfully inserted into porcine skin and were shown to dissolve gradually at 0 s, 60 s, 120 s, and 180 s after insertion. Microneedles containing methylene blue as model drug were also produced and successfully pierced porcine skin. 3D finite element (FEM) simulations were performed using the measured mechanical properties of the biopolymer films (Young's modulus 0.23 N/mm2 and tensile strength 1.8105 N/mm2) to evaluate the stress distribution on various dimensions of the fish scale derived microneedles and hence, their ability to withstand force necessary to pierce the skin without fracture. Results from mechanical analysis using FEM showed that microneedles with tip radius between 10 and 100 μm could withstand up to 0.12 N of force per microneedle without fracture, which is indicated when the stress at the tip of the microneedle exceeds the ultimate stress of the material of fabrication. Using skin insertion tests and finite element simulations, this study provides evidence that microneedles fabricated from fish scale biopolymer can effectively pierce and degrade into skin and therefore are good candidate for transdermal applications
Fracture behavior of boehmite-filled polypropylene block copolymer nanocomposites as assessed by the essential work of fracture concept

The essential work of fracture (EWF) method was adapted to determine the fracture toughness of poly(propylene-block-ethylene) (EPBC) based nanocomposites with different amounts (from 0 up to 5 wt.%) of synthetic boehmite alumina (BA). The dispersion of BA in the matrix was studied by transmission and scanning electron microscopies. Agglomerated micronscale along with well dispersed nanoscale BA particles were present in the EPBC matrix. By contrast to the neat EPBC, all nanocomposites failed by unstable necking. Therefore the energy partitioning concept of the EWF was adapted and attention paid to the yielding-related term. Both specific yielding-related essential and non-essential work of fracture parameters increased linearly with the product of the yield stress and elongation at yield derived from static tensile tests
Polyethylene flame retarded with expandable graphite and a novel intumescent additive

A novel intumescent additive was synthesized by neutralizing 3,5-diaminobenzoic acid hydrochloride
salt with ammonium dihydrogen phosphate. This compound, which melts at 257 °C, decomposes
concurrently to release carbon dioxide gas. The flame retardant performance of this compound as a
primary fire retardant and in combination with expandable graphite was evaluated by cone calorimetry.
Cone calorimeter results revealed that addition of 10 wt.% expandable graphite alone lowers peak heat
release rate of carbon black-pigmented polyethylene from 710 ± 109 kW m-2 to 342 ± 15 kW m-2, while
addition of 27 wt.% of the novel intumescent lowered it to 400 ± 16 kW m-2. Combinations of these two
additives were able to decrease the peak heat release rate even further. Furthermore, the novel
intumescent additive reduced the flame out time from 773 ± 307 s to 537 ± 69 s although all other
expandable graphite containing samples increased it.South African Research Chairs Initiative of the Department of Science and Technology (DST) and the National Research Foundation (NRF)http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1097-46282015-07-31hb201
Elastic biodegradable starch/ethylene-co-vinyl alcohol fibre-mesh scaffolds for tissue engineering applications

The fabrication of a biomaterial scaffold, with adequate physical and structural properties for tissue engineering applications, is reported. A blend of starch with ethylene-vinyl alcohol (50/50 w/w, SEVA-C) is used to produce 3D fibre-mesh scaffolds by wet-spinning. The scaffolds are characterized in terms of morphology, porosity, interconnectivity, and pore size, using scanning electron microscopy (SEM) and microcomputed tomography (Î¼CT). The degradation behavior, as well as the mechanical properties of the scaffolds, is investigated in presence of alpha-amylase enzyme at physiological concentration. Scaffolds with porosities ranging from 43 to 52%, interconnectivity of â\u88¼70.5% and pore size between 118 and 159 Î¼m, can be fabricated using the proposed methodology. The scaffolds exhibit an elastic behavior in the wet state with a compressive modulus of 7.96Â±0.32 MPa. Degradation studies show that SEVA-C scaffolds are susceptible to enzymatic degradation by alpha-amylase, confirmed by the increase of weight loss (40% of weight loss after 12 weeks) and presence of degradation products (reducing sugars) in solution. The diameter of SEVA-C scaffolds decreases with degradation time, increasing the overall porosity, interconnectivity and pore size. In vitro cell studies with human osteosarcoma cell line (SaOs-2) showed a nontoxic and cytocompatible behavior of the developed fibre mesh scaffolds. The positive cellular response, together with structural and degradable properties, suggests that 3D SEVA-C fibre-meshes may be good candidates as tissue engineering scaffolds. Â© 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40504. Copyright Â© 2014 Wiley Periodicals, Inc
New biomaterial based on cotton with incorporated biomolecules

The aim of this study was to investigate a method of embedding l-cysteine (l-cys), an antimicrobial agent, between layers of chitosan (CH) and sodium alginate (ALG) onto cotton samples obtained via a layer-by-layer electrostatic deposition technique via several embedding methods. The results show that the best way to incorporate l-cys into the layers was the one that used the property of gelling ALG. To monitor the l-cys embedding into the CH/ALG multilayer film, different methods were used: energy-dispersive X-ray spectrometry analysis to assess the presence of sulfur on the sample, Ellman's reagent method to analyze l-cys release from the sample, and attenuated total reflectance (ATR) Fourier transform infrared spectroscopy (FTIR) to compare the ATR–FTIR spectra of the pure l-cys and l-cys embedded in the CH/ALG multilayer film to study the interaction between the l-cys and the CH/ALG multilayer films. Functionalized CH/ALG cotton samples were also investigated for their antibacterial properties toward Staphylococcus aureus andKlebsiella pneumonia with the Japanese Industrial Standard method JIS L 1902:2002, and the results show an enhancement of the antibacterial effect due to the presence of l-cys.The authors thank Fundação para a Ciência e Tecnologia for the
funding granted concerning the project PTDC/EBB-BIO/113671/
2009 (FCOMP-01-0124-FEDER-014752). Also, they thank Fundo
Europeu de Desenvolvimento Regional through COMPETE—Programa
Operacional Factores de Competitividade for cofunding
Evaluating UV/H 2 O 2  exposure as a DEHP degradation treatment for plasticized PVC

Millions of tons of plasticized poly(vinyl chloride) (PVC) materials are disposed every year. A biologically sustainable and green method for removal of toxic plasticizers from polymer systems after disposal is highly desired since plasticizers can leach out into the environment over decades. Here we compare the surface and bulk structural changes of DEHP‐plasticized PVC after two treatments intended to degrade bis‐2‐ethylhexyl phthalate (DEHP) in PVC plastic: short wave (254 nm) UV with and without the addition of 35 wt % H 2 O 2.  Sum frequency generation vibrational spectroscopy (SFG) reveals the addition of aqueous H 2 O 2  decreases CH 3  signals on the surface of the films up to 8 h, due to increased molecular disorder and the removal of alkyl chains. Secondary ion mass spectrometry demonstrates that the degradation of DEHP after 8 h of reaction is similar with and without the use of H 2 O 2 . However, FTIR results reveal that the introduction of H 2 O 2  reduces bulk DEHP degradation and leads to competing radical chain scission reactions with PVC. Therefore, simple short wave UV exposure may be an effective means to degrade DEHP within and on PVC plastic and the addition of H 2 O 2  is only beneficial if additional degradation of PVC is needed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci.  2014 ,  131 , 40649
Piezoelectric co-axial filaments produced by co-extrusion of poly(vinylidene fluoride) and electrically conductive inner and outer layers

Article first published online: 3 APR 2014 : http://onlinelibrary.wiley.com/doi/10.1002/app.40710/abstract. DOI 10.1002/app.40710.The development of new thermoplastic polymer-based piezoelectric sensors with filament geometry is described. These filaments are appropriate for integration into textiles and provide new possibilities in the design and development of low cost flexible sensors produced at high rates. The developed three-layered piezoelectric monofilaments have been produced by co-extrusion using poly(vinylidene fluoride) and two different polypropylene-based electrically conductive polymers. Filaments with about 800 µm diameter, producing electrical signals proportional to the mechanical deformation applied, were obtained. The signal output has been found adequate for straightforward use with conventional piezoelectric signal conditioning systems. One of the conductive polymers tested allowed better filament geometry and process stability. This paper describes the co-extrusion production process and the results obtained in the electromechanical tests performed.This work was supported by FEDER through the COMPETE Program and by the Portuguese Foundation for Science and Technology (FCT) by project PTDC/CTM/108801/2008 | FCOMP-01-0124-FEDER-009480 and in the framework of the Strategic Project PEst-C/FIS/UI607/20112011, PEst-C/CTM/LA0025/2013 (Strategic Project - LA 25 - 2013-2014) and PEst-C/CTM/UI0264/2011. Authors also thank the project Matepro –Optimizing Materials and Processes”, ref. NORTE-07-0124-FEDER-000037”, co-funded by the “Programa Operacional Regional do Norte” (ON.2 – O Novo Norte), under the “Quadro de Referência Estratégico Nacional” (QREN), through the “Fundo Europeu de Desenvolvimento Regional” (FEDER
Improving heat ageing and thermal properties of silicone rubber using montmorillonite clay

This is the peer reviewed version of the article, which has been published in final form at . This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.Heat ageing and thermal stability of a silicone rubber (SR) filled with montmorillonite clay (MMT) was investigated.\ud
Three types of rubber nanocomposites were prepared with hig hly exfoliated Cloisite 30B (SR/C30B), intercalated/exfoliated Cloisite\ud
Na\ud
1\ud
(SR/Na\ud
1\ud
MMT), and highly intercalated Cloisite 20A (SR/C20A). This study showed that the SR/C30B nanocomposite exhibited\ud
excellent heat resistance in comparison to the other two nanocomposites and neat SR as revealed by higher retention strength. The\ud
thermal stability of the rubber in air was strongly dependent on the clay morphology and increased in the following order: highly\ud
intercalated/exfoliated SR/Na\ud
1\ud
MMT < highly intercalated SR/C20A < highly exfoliated SR/C30B. The thermogravimetric analyses of the SR/C30B nanocomposite showed a substantial increase in the final residue in comparison with the neat SR. This indicated a\ud
major improvement in the thermal stability of the rubber containing the exfoliated clay, which was also supported by the higher activation energy of decomposition measured for the nanocomposite
Impact of the coating process on the molecular structure of starch-based barrier coatings

Molecular analysis of starch structure can be used to explain and predict changes in physical properties, such as water vapor and oxygen barrier properties in packaging materials. Solution casting is a widely used technique to create films from starch formulations. This study compared the molecular properties of these standard films with those of experimental coatings applied to paper in laboratory-scale and pilot-scale trials, with all three techniques using the same starch formulation. The results revealed large differences in molecular structure, i.e., cross-linking and hydrolysis, between films and coatings. The main differences were due to the shorter drying time allowed to laboratory-scale coatings and the accelerated drying process in pilot trials owing to the high energy output of infrared dryers. Furthermore, surface morphology was highly affected by the coating technique used, with a rougher surface and many pinholes occurring in pilot-scale coatings, giving lower water vapor permeability than laboratory-scale coatings
Ultra-high enhancement in the toughness of polyethylene by exfoliated natural clay nanosheets

This is the peer reviewed version of the following article: CAI, D. and SONG, M., 2015. Ultra-high enhancement in the toughness of polyethylene by exfoliated natural clay nanosheets. Journal of Applied Polymer Science, 132 (1), 41314, which has been published in final form at http://dx.doi.org/10.1002/app.41314. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.The full exfoliation of inorganic natural clay was engineered in a nonpolar polyethylene following a novel method without the involvement of any chemical modification to the surface of silicate layers. Tensile results showed that the toughening effect was dependent of strain rates, and the toughness of polyethylene was substantially improved by nearly five times with 0.5 wt % natural clay nanosheets at a strain rate of 0.15 s−1. Toughening mechanism was also discussed based on this new exfoliated syste
Olive leaf extract as a crosslinking agent for the preparation of electrospun zein fibers

Incorporating active agents, reinforcing structure by crosslinking, thus changing release properties, can be listed as possible modifications in preparation methods of biopolymer fibers. This study introduces oleuropein, major component of olive leaf extract (OLE), as a natural functional crosslinker for electrospun zein fibers, owing to its antioxidant and antimicrobial properties. Incorporation of OLE causes morphological and structural changes indicated by a decrease in fiber diameter up to 27%, an increase in intensity of NH bending region due to interaction with -OH groups and observation of characteristic oleuropein bands. Extract addition also enhances thermal stability. Zein fibers without OLE is fully degraded at 600C, whereas 10% of OLE loaded zein fibers is left undegraded. Fifty percent of initial phenolic content loaded into fibers is released which indicate the effect of OLE incorporation as accumulation of oleuropein. OLE-incorporated fibers immersed in PBS are less fused than pure zein fibers, due to the crosslinking effect
Cure efficiency of dodecyl succinic anhydride as a cross-linking agent for elastomer blends based on epoxidized natural rubber

This is the peer reviewed version of the article, which has been published in final form at http://dx.doi.org/10.1002/app.41448. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.Blends of a highly epoxidized natural rubber (ENR50) with unmodified natural rubber (NR) and ethylene propylene elastomers (EPDM) were produced to evaluate the mixing and curing characteristics. Dodecyl succinic anhydride was used to cross-link the ENR50 component and the reactivity was assessed by monitoring the evolution of the torque in an oscillatory co-axial cylinder rheometer, as well as by DSC thermal analysis. A physical model was used to obtain a single parameter for the reactivity of the system, which corresponds to the rate constant for first order curing reactions. Although the blends were thermodynamically immiscible, displaying no significant change in Tg, the components were well dispersed at microscopic level. Better mechanical properties were obtained for blends with EPD
Flame retarding effect of graphite in rotationally molded polyethlene/graphite composites

Linear low density polyethylene (LLDPE) compounds containing 10 wt.% graphite fillers were
rotationally molded into flat sheets. Flame retardancy was studied using cone calorimeter tests
conducted at a radiative heat flux of 35 kW m2. Only the expandable graphite, an established flame
retardant for polyethylene, significantly reduced the peak heat release rate. Compared to the neat
polyethylene, it was easier to ignite the LLDPE composites containing carbon black, expandable
graphite and exfoliated graphite. However, rather unexpectedly, the inclusion of flake graphite
increased the time to ignition by up to 80%. Simulations conducted with the ThermaKin numerical
pyrolysis software suggest that increased reflectivity was mainly responsible for this effect.The South African Research Chairs Initiative of
the Department of Science and Technology (DST) and the National Research Foundation
(NRF) as well as Xyris Technology CC.http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1097-46282016-02-20hb201
Dynamic Properties of Magnetorheological Elastomers Based on Iron Sand and Natural Rubber

In this study, magnetorheological elastomers (MREs) based on iron sand and natural rubber were prepared. The Taguchi method was employed to investigate the effect of a number of factors, namely, the iron sand content, iron sand particle size, and applied magnetic field during curing on the loss tangent (tan δ) and energy dissipated during cyclic loading. Tan δ was measured through dynamic mechanical analysis over a range of frequency (0.01–130 Hz), strain amplitude (0.1–4.5%), and temperature (−100 to 50°C). The energy dissipated was measured with a universal tester under cyclic tensile loading. The data were then statistically analyzed to predict the optimal combination of factors, and finally, experiments were conducted for verification. It was found that the iron sand content had the greatest influence on tan δ when measured over a range of frequency, and the energy dissipated during hysteresis tests. However, none of the factors showed a significant influence on tan δ when measured over a range of strain amplitude. Furthermore, the iron sand content and magnetic field were also found to influence the width of the peak in tan δ as a function of the temperature. The morphological characteristics of the MREs were also examined with scanning electron microscopy