Surface and bulk properties improvement of HDPE by a batch plasma treatment

High‐density polyethylene (HDPE) pellets were modified via atmospheric plasma treatment using nitrogen flushing. The new application of plasma treatment was introduced in this work, namely a batch treatment on plastic pellets just prior to its feeding to the extrusion process in comparison with the conventional surface treatment of the plastic sheet. The effect of treatment time (15–120 s) on wettability, chemical, thermal, and mechanical properties of the modified HDPE were investigated and compared with the typical surface‐treated HDPE and untreated HDPE. The pellet treatment distributed well the hydrophilicity groups so that both surface and bulk properties were improved. It showed an enhancement of wettability similar to surface treatment at short treatment time (15 s). Attenuated total reflection‐Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy revealed the presence of new chemical groups (nitrogen and oxygen up to 5 and 42 at %, respectively). In addition, crosslinked structure was also disclosed by solvent extraction (gel content of 3.5–5.5 wt % increased with treatment time) and significantly affected to decrease the crystallinity from 76% in the untreated sample to 63%. The decomposition process of the pellet treatment samples was delayed. Lastly, pellet treatment yielded advantages in remaining hydrophilicity during aging and improving mechanical properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43011.     

Some metal compounds in the phase of crosslinked ionic polymer—precursors for new sorbents and catalysts

A commercial crosslinked ionic polymer AV‐17 containing ? N(CH₃)₃Cl groups was used. The common compounds of Bi(III) and Al(III); Bi(III) and Cr(III); Bi(III) and Fe(III); Bi(III) and FeOOH and of three components—Bi(III), Fe(III), and Cr(III); Bi(III), FeOOH, and Cr(III) were obtained in the AV‐17 polymer phase and investigated using scanning electron microscopy, powder X‐ray diffraction, thermogravimetric analysis, and Fourier‐transform infrared spectroscopy. It was shown that metal‐containing compounds were concentrated on the surface of the polymer granules. The compounds were in the crystalline (BiOCl) or amorphous (jarosites and oxihydroxides) state. The morphology and composition of the metal‐containing ultra dispersed particles were different on the surface and in the volume of the polymer granule. Most of the metal‐containing compounds were in the form of pseudo spherical particles, but compounds containing Bi(III) and FeOOH in the volume of AV‐17 granule, were in the form of clew of nanometer fibers. Thermogravimetric analysis (in an N₂ atmosphere) in the range 24–1000°C of the metallic compounds containing polymer was also carried out. The metal‐containing polymer samples were stable up to 120°C. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Effect of different compatibilisers on nanoclay dispersion,thermal stability,and burning behavior of polypropylene–nanoclay blends

The dispersion of nanoclays in nonpolar polypropylene (PP) is difficult without the use of a small fraction (1–3%) of modified grafted PP as a compatibiliser. This work reports the effect of different graft‐modified polypropylenes on the dispersion of nanoclays in PP, and thermal stability and flammability of the blends. PP has been compounded in a Brabender compounder with a selection of modified PP polymers as compatibilisers. The grafts include maleic anhydride, N‐ethylmaleimide, diethylmaleate, diethyl‐p‐vinylbenzyl phosphonate, and acrylic acid‐2‐[(diethoxyphosphoryl)methylamino] ethyl ester. Films were cast from the blends by compression molding and the nanocomposite structures assessed using X‐ray diffraction. Thermal characterization was performed using DSC and TGA, the burning behavior was observed using limiting oxygen index measurements, and cone calorimetry where samples were exposed to 35 kW/m² external heat flux. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Three‐dimensional mapping of crystalline ceramic waste form materials

This work demonstrates the use of synchrotron‐based, transmission X‐ray microscopy (TXM) and scanning electron microscopy to image the 3‐D morphologies and spatial distributions of Ga‐doped phases within model, single‐ and two‐phase waste form material systems. Gallium doping levels consistent with those commonly used for nuclear waste immobilization (e.g., Ba_1.04Cs_0.24Ga_2.32Ti_5.68O₁₆) could be readily imaged. The analysis suggests that a minority phase with different stoichiometry/composition from the primary hollandite phase can be formed by the solid‐state ceramic processing route with varying morphology (globular vs. cylindrical) as a function of Cs content. The results presented in this work represent a crucial step in developing the tools necessary to gain an improved understanding of the microstructural and chemical properties of waste form materials that influence their resistance to aqueous corrosion. This understanding will aid in the future design of higher durability waste form materials.     

Graft copolymerization of acrylamide onto carboxymethylcellulose with the xanthate method

Acrylamide was grafted to an xanthate mixture of carboxymethylcellulose with a sodium bisulfate/ammonium persulfate redox initiator system in water, sodium hydroxide, potassium hydroxide, and dioxane at 40, 50, 60, 70, and 80°C during a reaction period of 2 h. The grafted polymer and homopolymer were isolated with diethyl ether from the reaction mixture, dried, and weighed. The grafted polymer was characterized with IR and mass spectrometry methods, and the microscopic morphology was detected with electron scanning microscopy. The graft level percentage distinctly increased with the use of sodium hydroxide, potassium hydroxide, and dioxane over that of a reaction carried out completely in an aqueous medium. Also, the graft level decreased as the reaction temperature increased. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 271–278, 2004     

Effect of working conditions on the morphology of electrosynthesized polyfuran

The influence of electrolyte and deposition potential on polyfurane doped/undoped electrogenerated films was analyzed by potentiodynamic profiles and current–time transients. The films were formed on platinum electrodes from the monomer and tetrabutylammonium hexafluorophosphate, tetrabutylammonium tetrafluoroborate, or tetraethylammonium perchlorate in acetonitrile. Results were also discussed with the aid of X‐ray photoelectron spectroscopy (XPS), electron probe microanalysis (EPMA), and primarily by scanning electron microscopy (SEM). It was shown that there is some oxygen contamination not only after ClO₄ doping. However, it was shown by XPS and EPMA that C? O? C bonds are present in the films, which confirmed that there was no destruction of the furan ring during electropolymerization. SEM study showed film morphology evolution with monomer concentration, and with the electrolyte or the dopant used. The undoping effect was also visualized, showing that doped polyfuran was more homogeneous than the respective undoped deposits. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1346–1354, 2004     

Synthesis and characterization of a copolymer: Poly(aniline‐co‐fluoroaniline)

In the present article, we report the chemical synthesis and characterization of poly(aniline‐co‐fluoroaniline) [poly(An‐FAn)]. The copolymerization of aniline and 2‐fluoroaniline was carried out by chemical method in acidic medium. The characterization of poly(aniline‐co‐fluoroaniline) was done using FTIR, UV‐visible spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), scanning electron micrography (SEM), and a four‐points‐probe conductivity method. X‐ray diffraction (XRD) and SEM characterization reveal crystalline nature of doped copolymer compared to undoped copolymer. The observed decrease in the conductivity of the copolymer relative to polyaniline is attributed to the incorporation of the fluoro moieties into the polyaniline chain. The chemically synthesized copolymer shows good solubility in common organic solvents, and is, therefore, technological useful. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1460–1466, 2001     

Graft copolymerization of methoxyacrylethyl phosphate onto expanded poly(tetrafluoroethylene) facial membranes

Expanded poly(tetrafluoroethylene) (ePTFE) membranes were modified by graft copolymerization with methoxyacrylethyl phosphate (MOEP) in methyl ethyl ketone (MEK) solutions at ambient temperature using gamma irradiation. The effect of monomer concentration (3–30%) was studied and the modified membranes were characterized by weight increase, x‐ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), contact angle measurements, and differential scanning calorimetry (DSC). Results show that the ePTFE membrane had a degree of crystallinity of 59% and that this did not significantly change after grafting indicating that grafting occurs in the amorphous regions. SEM images showed a globular surface morphology for the grafted membranes. XPS was used to evaluate the chemical structure of the graft copolymer and to determine the XPS grafting extent using the C‐F (ePTFE membrane) and the C‐C (MOEP graft copolymer) peaks. The graft yield as well as grafting extent was found to increase with increasing monomer concentration. Concomitantly, the contact angle was found to decrease with increasing monomer concentration. No direct correlation was found between XPS grafting extent and the advancing water contact angle illustrating that the former does not adequately give an indication of the copolymer surface coverage of the first molecular layer. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

High‐temperature oxidation of aniline to highly ordered polyaniline–sulfate salt with a nanofiber morphology and its use as electrode materials in symmetric supercapacitors

In this study, for the first time, aniline was oxidized by ammonium persulfate (APS) at higher temperatures without any protic acid, and APS acted as an oxidizing agent and a protonating agent. During the oxidation of aniline by APS, sulfuric acid formation occurred, and the sulfuric acid was incorporated into polyaniline (PANI) as a dopant. PANI–sulfate samples were characterized by IR spectroscopy, X‐ray diffraction, and scanning electron microscopy techniques. In this methodology, a highly ordered PANI–sulfate salt (H₂SO₄) with a nanofiber morphology was synthesized. Interestingly, a PANI base was also obtained with a highly ordered structure with an agglomerated netlike nanofiber morphology. PANI–H₂SO₄ was used as an electrode material in a symmetric supercapacitor cell. Electrochemical characterization, including cyclic voltammetry (CV), charge–discharge (CD), and impedance analysis, was carried out on the supercapacitor cells. In this study, the maximum specific capacitance obtained was found to be 273 F/g at 1 mV/s. Scan rate from cyclic voltammetry and 103 F/g at 1 mA discharge current from CD measurement. Impedance measurement was carried out at 0.6 V, and it showed a specific capacitance of 73.2 F/g. The value of the specific capacitance and energy and power densities for the PANI–H₂SO₄ system were calculated from CD studies at a 5‐mA discharge rate and were found to be 43 F/g, 9.3 W h/kg, and 500 W/kg, respectively, with 98–100% coulombic efficiency. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Rubber–clay nanocomposite by solution blending

Ethylene vinyl acetate rubber (45% vinyl acetate content, EVA‐45) and organomodified clay (12Me‐MMT) composites were prepared by solution blending of the rubber and the clay. A combination of X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy studies showed that the composites obtained are on the nanometer scale. The measurements of the dynamic mechanical properties for different compositions over a temperature range (?100 to +100°C) showed that the storage moduli of these rubber–clay nanocomposites are higher above the glass to rubber transition temperature compared to the neat rubber. The tensile strength of the nanocomposites is about 1.6 times higher than that of the EVA‐45. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2216–2220, 2003     

Enhancing magnetic levitation and guidance force and weight efficiency of high-temperature superconducting maglev systems by using sliced bulk YBCO

We aimed to enhance the magnetic force efficiency of Maglev systems without increasing total weight. For this aim, we divided YBCO bulks into three slices horizontally to utilize the YBCO-permanent magnetic guideway (PMG) interaction surface as much as possible. We used whole YBCO above PMGs with different magnetic pole directions (PMG-A and PMG-B) in two lying positions of transversal and longitudinal and investigated levitation and guidance force performances. It is determined that levitation and guidance forces by using YBCO in transversal lying mode are bigger compared to the longitudinal mode. For sliced YBCO, the maximum levitation force increased by 69% and 78%, while the guidance force enhancements are determined as 212% and 91%, compared to the whole YBCO above PMG-A and PMG-B, respectively. The levitation and guidance force density with respect to the total mass of unit a set of slices YBCO increased by 92% and 106%, respectively, compared to the whole YBCO above PMG-B in transversal mode. Since the higher levitation force and the lower total weight of the onboard unit are important parameters in point of the energy efficiency in Maglev and other levitation applications, the result of this study supplies useful data for the engineers and industrial partners.     

Elaboration and thermal analysis of nanocomposites based on poly(methyl methacrylate‐co‐4‐vinylpyridine) and Maghnia bentonite

Nanocomposites based on an organically modified bentonite, from Maghnia Algeria (OBT) and a copolymer of methyl methacrylate with 4‐vinylpyridine (PMM4VP) synthesized in dioxan at room temperature using a neutral Ni(II)α‐benzoinoxime complex as a single component initiator, were elaborated via solution intercalation method and characterized by several techniques. X‐ray diffraction and transmission electron microscopy investigations indicate that mainly exfoliated and intercalated PMM4VP/OBT nanocomposites were elaborated and that the degree of exfoliation decreases with an increase of the OBT loading. Thermal analyses of these nanocomposites compared with their virgin copolymer confirmed a significant improvement of their thermal stability as evidenced by an increase of 28°C in their onset degradation temperatures. In addition, differential scanning calorimetry displayed an increase in the range of 12–18°C in their glass transition temperatures relative to their virgin copolymer. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Self‐welding 1‐butene/ethylene copolymers from metallocene catalysts: Structure,morphology, and mechanical properties

Samples of random copolymers consisting of 1‐butene modified with a low ethylene content (4, 5, 8% by weight) produced with metallocene catalysts were studied to elucidate the polymorphic behavior of this new class of materials and to characterize them from a structural, morphological, and mechanical point of view. The samples cooled down from the melt are in amorphous phase and crystallize in a mixture of form I and I′ or in pure form I′ with aging time, according to the C2 content. Infrared and nuclear magnetic resonance spectroscopy, X‐ray diffraction and microscopic techniques were used to follow the changes of the material with aging time and to correlate the structural and morphological behavior with the peculiar mechanical properties that differentiate the samples with increasing C2 content. The presence, in the aged samples with higher C2 content, of the pure form I′ induces the peculiar ability to self‐welding and these copolymers combine high flexibility with good elasticity and ductility and can be processed directly or used as modifying agents in polymers. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40119.     

Thermal,mechanical, and water vapor barrier behavior of polypropylene composite containing modified kaolinite

Polypropylene composites containing modified kaolinite were prepared using melt processing and the morphological, thermal, mechanical and their water barrier properties were analyzed. To improve compatibility with polypropylene, kaolinite was modified with silane as a coupling agent. Characterization techniques (X‐ray diffraction, Fourier transform infrared spectroscopy, and X‐ray photoelectron spectroscopy) confirmed the effective grafting of these compounds on the surface and edges of the kaolinite with no functionalization on the inner surface. The differential scanning calorimetry and X‐ray diffraction techniques demonstrated that the addition of grafted kaolinite affected the iPP crystallinity. The thermogravimetric analysis helped to determine the thermal stability of the composites, being this, dependent on the amount of kaolinite and silane. The stress–strain tests demonstrated an increase in Young's modulus and obtained a 70% reduction in water vapor permeation. These improvements were mainly related to the increased compatibility between the iPP/Kaol interfaces promoted by the silane. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45785.     

Computation of sintering stress and bulk viscosity from microtomographic images in viscous sintering of glass particles

Sintering stress and bulk viscosity were derived as functions of relative density from microtomographic images in viscous sintering of glass particles. Three methods were proposed to estimate the sintering stress from relative density, specific surface area, and average of curvature on pore surface, which were directly measured by X‐ray microtomography. The surface energy method gave valid value in the final stage of sintering, while the mixed method gave better estimation in the intermediate stage. For the initial stage of sintering, the sintering stress was calculated from the average contact radius and the average coordination number observed by X‐ray microtomography. The sintering stress at the final stage increased in free sintering, but it decreased in constrained sintering due to pore coarsening. The bulk viscosity was calculated from the shrinkage rate and the sintering stress.     

Preparation,structural development,and mechanical properties of microfibrillar composite materials based on polyethylene/polyamide 6 oriented blends

The preparation of microfibrillar composites (MFCs) based on oriented blends of polyamide 6 (PA6) and high‐density polyethylene (HDPE) is described. By means of conventional processing techniques, the PA6 phase was transformed in situ into fibrils with diameters in the upper nanometer range embedded in an isotropic HDPE matrix. Three different composite materials were prepared through the variation of the HDPE/PA6 ratio with and without a compatibilizer: MFCs reinforced by long PA6 fibrils arranged as a unidirectional ply; MFCs containing middle‐length, randomly distributed reinforcing PA6 bristles; and a nonoriented PA6‐reinforced material in which the PA6 phase was globular. The evolution of the morphology in the reinforcing phase (e.g., its visible diameter, length, and aspect ratio) was followed during the various processing stages as a function of the blend composition by means of scanning electron microscopy. Synchrotron X‐ray scattering was used to characterize selected unidirectional ply composites. The presence of transcrystalline HDPE was demonstrated in the shell of the reinforcing PA6 fibrils of the final MFCs. The impact of the compatibilizer content on the average diameter and length of the fibrils was assessed. The influence of the reinforcing phase on the tensile strength and Young's modulus of the various composites was also evaluated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Microstructural changes of phenolic resin during pyrolysis

After curing, phenol‐formaldehyde resins were postcured at 230°C in air for 32 h and then carbonized and graphitized from 300 to 2400°C. Thermal fragmentation and condensation of the polymer structure occurred above 300°C. The crystal size of the cured phenolic resins decreased with the temperature increase. Above 600°C the original resin structures disappeared completely. Below 1000°C the stack size (L_c) and crystal size (L_a) were small. Above 1000°C the L_c increased with the increasing treatment temperature. The carbonized and graphitized resins were characterized using Raman spectroscopy. Below 400°C there were no carbon structures in the Raman spectra analysis. Above 500°C the G and D bands appeared. The frequency of the G band of all carbonized and graphitized samples shifted to 1600 cm^?1 from the 1582 cm^?1 of graphite. The D band shifted to 1330 cm^?1 from the 1357 cm^?1 of the imperfect carbon. The carbonized and graphitized phenolic resins could not be considered as truly glassy or amorphous carbon materials because they had some degree of order in the basal plane. However, the crystal size was very small even at 2400°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1084–1089, 2001     

Study of various interventions in the façades of a historical building—Methodology proposal,chromatic and material analysis

Visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), and energy dispersive X‐ray spectroscopy (EDS) in addition to scanning electron microscopy (SEM) have been used for determining the color and chemical composition of the architectural elements of the façades of a historical building, which today is the seat of the Diputación Provincial of Cadiz. It dates from 1770 and was built as Custom Headquarters. It is near the port and is almost encircled by the walls of the city. The determination of the color and chemical composition of the materials that provoke this color and the determination of the layers found in the extracted samples from significant zones allow to define the various interventions over the façade and to localize the time in which they were made. This is possible by comparing with graphical registries and historical documentation. The objective is a study of the color of the different façades that the building has had in order to know the history of the building and to choose materials and colors that should be used in a restoration intervention of this historical building. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 382–390, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.     

The effect of sulfonation treatment on the structure and properties of isotactic polypropylene fibers prior to the carbonization stage

The effect of sulfonation treatment was investigated on the molecular structure and mechanical properties of isotactic polypropylene fibers extruded at a take up speed of 2500 m/min. It was found that at extensive sulfonation times, the sulfonated structure showed the characteristic features of carbonized structure as indicated by the results of the density and the X‐ray diffraction measurements. Mechanical properties of the sulfonated samples were found to be adversely affected by the sulfonation conditions. Scanning electron microscopy observations showed surface irregularities at low sulfonation times and fiber fractures at high sulfonation times. Polarized infrared spectroscopy measurements analysed by curve fitting procedure showed increasing molecular orientation of long helical chain segments represented by the IR band at 841 cm^?1 whereas amorphous structure represented by the IR band at 2723 cm^?1 showed gradual loss of orientation with the progress of sulfonation. IR bands assigned to the sulfonic acid groups formed during sulfonation treatment showed perpendicular polarization and low molecular orientation characteristics indicating the initiation and the development of crosslinking process being perpendicular to the fiber axis direction. Analysis of the equatorial X‐ray diffraction traces showed the loss of crystallinity where the paracrystalline phase disappeared faster than the crystalline α‐monoclinic phase. During the sulfonation treatment, content of amorphous phase showed gradual increase in line with decreasing crystallinity. In accordance with the loss of crystallinity, apparent crystallite sizes corresponding to the 110, 040 and 130 planes of the α‐monoclinic phase also decreased gradually with increasing sulfonation time. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012