Cationization of cellulose/polyamide on UV protection,bio‐activity,and electro‐conductivity of graphene oxide‐treated fabric

In this work, cationized cotton/nylon fabric was treated with reduced graphene oxide (rGO) to produce highly conductive fabric. The fabric was cationized with 3‐chloro‐2‐hydroxy propyl trimethyl ammonium chloride to attract more anionic GO. The fabric was then treated with GO followed by reduction with sodium dithionite. The results of energy‐dispersive X‐ray spectroscopy, X‐ray diffraction, and X‐ray photoelectron spectroscopy indicated entire coverage of the fabric surface with rGO. The color of fabrics changed to gray‐black and the electrical resistance decreased to 0.6 × 103 Ω sq^?1. The washing fastness was measured according to ISO 105‐CO5 for color change and also electrical resistance of the samples demonstrated well stability of rGO on the fabric surface. The antibacterial activities of the treated fabrics improved against Gram‐negative bacteria including Escherichia coli (84.8%) and Pseudomonas aeruginosa (96.4%) and also Gram‐positive bacteria consisting Staphylococcus aureus (100%) and Enterococcus faecalis (98.4%). Further, the treated fabrics indicated an excellent UV reflectance of 100%. Finally heating of the cationized rGO fabric at 220 °C displayed a lower electrical resistance of 0.5 × 103 Ω sq^?1. The thermogravimetric analysis showed that heating has a slight effect on the dimensional thermal stability of the treated fabric as shrunk 2.43%. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45493.     

Texture and morphology of biaxially stretched poly(ethylene naphthalene‐2,6‐dicarboxylate)

The orientation of poly(ethylene naphthalene‐2,6‐dicarboxylate) (PEN) films with different morphologies were studied by wide‐angle X‐ray diffraction. Different structures were obtained by thermally treating biaxially stretched PEN samples. Virgin and thermally treated (1 h at 240, 250, and 260°C) samples of PEN bioriented films were characterized by DSC to determine the glass‐transition temperature and the crystallinity ratio. To define the orientation of crystallites in the 25 μm thick bioriented samples, pole figures were recorded for various PEN samples, as a function of their position in the transverse drawing direction. The significant result is that there is a dominant crystal population, whose c‐axis direction varies from +45° at one sample edge to ?45° at the other edge, the orientation at the center being parallel to the transverse direction. There is also a secondary population, which can be seen only near the center. DSC studies also showed that by increasing the annealing temperature the crystallinity ratio was increased and pole figures showed that the texture was modified, probably because of disorientation mainly from an annealing temperature of 260°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2224–2232, 2003     

Thermal exposure effects on the long‐term behavior of a mullite fiber at high temperature

The behavior of an oxide fiber at elevated temperatures was analyzed before and after thermal exposures. The material studied was a mullite fiber developed for high‐temperature applications, CeraFib 75. Heat treatments were performed at temperatures ranging from 1200°C to 1400°C for 25 hours. Quantitative high‐temperature X‐ray analysis and creep tests at 1200°C were carried out to analyze the effect of previous heat treatment on the thermal stability of the fibers. The as‐received fibers presented a metastable microstructure of mullite grains with traces of alumina. Starting at 1200°C, grain growth and phase transformations occurred, including the initial formation of mullite, followed by the dissociation of the previous alumina‐rich mullite phase. The observed transformations are continuous and occur until the mullite phase reaches a state near the stoichiometric 3/2 mullite. Only the fibers previously heat treated at 1400°C did not show further changes when exposed again to 1200°C. Overall, the heat treatments increased the fiber stability and creep resistance but reduced the tensile strength. Changes observed in the creep strain vs. time curves of the fibers were related to the observed microstructural transformations. Based on these results, the chemical composition of the stable mullite fiber is suggested.     

Thermal Expansion of Alkaline‐Doped Lanthanum Ferrite Near the Néel Temperature

The thermal expansion and magnetic behaviors of divalent, alkaline‐doped lanthanum ferrites (La_0.9M_0.1FeO₃, M=Ca, Sr, Ba) were assessed using a combination of dilatometry, magnetometry, time‐of‐flight neutron diffraction, and high‐temperature X‐ray diffraction. Néel temperatures were determined through vibrating sample magnetometry and correlated well with changes in thermal expansion behavior observed during both dilatometry and X‐ray diffraction. The Néel temperatures observed for pure, Ca‐doped, Sr‐doped, and Ba‐doped lanthanum ferrites were 471°C, 351°C, 465°C, and 466°C, respectively. The effect of divalent substitutions on the magnetic behavior are attributed to charge compensation mechanisms and structural changes in the material.     

Less‐ordered lamellar structure of intercalated poly(L‐lactide)/organo‐modified montmorillonite hybrids

Hybrids of poly(L ‐lactide)/organophilic clay (PLACHs) have been prepared via a melt‐compounding process using poly(L ‐lactide) (PLLA) and different contents of surface‐treated montmorillonite modified with dimethyl dioctadecyl ammonium‐salt. The crystalline structures of PLLA and dispersion states of clay particles in those PLACHs were investigated by use of wide‐angle X‐ray diffraction, small‐angle X‐ray scattering, transmission electron microscopy (both cross section and replication modes), and polarized optical microscopy. Those structures are viewed from the conformational changes of PLLA chains in the space of a few nanometer widths between silicate galleries to crystalline lamellae of several nanometer thicknesses, and spherulitic textures more than micrometer sizes. After annealing treatments at 115°C for 1 hr, the PLACHs formed coarse‐grained spherulitic textures with 40 μm diameter composed of less‐ordered and fragmented lamellae, caused by the reduced mobility of the PLLA chain due to the dispersed clay particles in the PLLA matrix and the intercalation of the PLLA chains in the silicate galleries. The formation of the interfibril structure accompanied by the fragmented lamellae among the dispersed clay particles was examined. POLYM. ENG. SCI., 46:703–711, 2006. © 2006 Society of Plastics Engineers     

Chemical grafting of curcumin at polyethylene terephthalate woven fabric surface using a prior surface activation with ultraviolet excimer lamp

Durable curcumin‐treated antibacterial polyethylene terephthalate (PET) fabrics (against Staphylococcus aureus) were produced by dyeing with curcumin after surface activation using vacuum ultraviolet excimer lamp at 172 nm. Surface change properties of the exposed fabrics were characterized by surface analysis methods such as wettability, atomic force microscopy, and X‐ray photoelectron spectroscopy. Results show an increase in surface hydrophilicity with a water contact angle of the PET fabric reaching 24° after 10 min excimer irradiation, which could be attributed to an increase in carboxyl group formation as confirmed by X‐ray photoelectron spectroscopy measurements. Varying concentrations of curcumin were immobilized onto untreated and vacuum ultraviolet‐irradiated PET samples using diffusion method at 90°C, and the treated fabrics characterized using K/S (color strength) values at 440 nm. K/S values increased when the PET surface was subjected to a prior excimer irradiation, because of grafting of curcumin at the PET surface. Increased excimer irradiation time increased grafting of curcumin because the inner fabric fiber surfaces were also more thoroughly treated. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Properties and antimicrobial efficacy of cellulose fiber coated with silver nanoparticles and 3‐mercaptopropyltrimethoxysilane (3‐MPTMS)

Silver nanoparticles were coated onto cotton fabrics with 3‐mercaptopropyltrimethoxysilane (3‐MPTMS). The coating process was accomplished by soaking the cotton fabrics into silver colloid/3‐MPTMS solution at 43°C for 90 min. The coated fabrics were characterized by scanning electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). SEM images showed a layer of silver nanoparticles and 3‐MPTMS on cotton. The XPS data showed that distinguishable binding energy peaks of Ag 3d, Si 2p, Si 2s, S 2p were 368/374, 102, 153, and 162 eV, respectively, which confirms the existence of silver and 3‐MPTMS on cotton fabrics. The treated cotton fabrics showed prominent antimicrobial effectiveness against Staphylococcus aureus (ATCC 6538) and Klebsiella pneumonia (ATCC 4352). Furthermore, the laundry test showed that 66% of silver nanoparticles were retained after five washing cycles. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Structural changes of polylactic‐acid (PLA) microspheres under hydrolytic degradation

Low molecular‐weight polylactic acid (PLA) was obtained by direct polycondensation of a mixture of 95% l and 5% d ‐lactic acid isomers, without catalyst, at 195°C. This polymer was used for the synthesis of microspheres by emulsion–solvent evaporation method. Gel Permeation Chromatography (GPC), X‐ray Scattering (XRD), Differential Scanning Calorimetry (DSC), and Scanning Electron Microscopy (SEM) techniques were applied to follow morphological and structural changes of particles along in vitro degradation at 37°C. The original microspheres were amorphous but could crystallize partially upon heating. Samples stored in a humid environment exhibited an increase in the crystallization capability upon heating. Initial smooth‐surface microspheres were transformed to porous particles at the time of degradation at pH = 7 (37°C). The shape of mass loss vs. time curve supports the presence of a heterogeneous bulk degradation process. After hydrolytic degradation the residual particles showed a molecular weight decrease and a crystallinity increase. After 90 days the crystallinity attained a value of 53%. The X‐ray diffraction spectrum indicated the formation of a crystalline oligomeric structure. Crystallization of low molecular weight species will not enable the desired PLA absorption in drug delivery systems. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1223–1230, 1999     

Synthesis of Nanofiber‐like Mesoporous γ‐Al2O3 toward Its Adsorption Efficiency for Congo Red

Nanofiber‐like mesoporous γ‐Al₂O₃ was synthesized using freshly prepared boehmite sol in the presence of triblock copolymer, P123 following evaporation‐induced self‐assembly (EISA) process followed by calcinations at 400°C–1000°C. The samples were characterized by thermogravimetry (TG), differential thermal analysis (DTA), X‐ray diffraction (XRD), N₂ adsorption–desorption, and transmission electron microscopy (TEM). The adsorption efficiency of the samples with Congo red (CR) was studied by UV – vis spectroscopy. XRD results showed boehmite phase in the as‐prepared sample while γ‐Al₂O₃ phase obtained at 400°C was stable up to 900°C, a little transformation of θ‐Al₂O₃ resulted at 1000°C. The Brunauer‐Emmett‐Teller surface area of the 400°C‐treated sample was found to be 175.5 m²g ^{? 1}. The TEM micrograph showed nanofiber‐like morphology of γ‐Al₂O_3. The 400°C‐treated sample showed about 100% CR adsorption within 60 min.     

Thermally induced chemical evolution in polyimide films investigated by X‐ray photoelectron spectroscopy

Thermally modified polyimide films based on 1,4‐Phenylene diamine (p‐PDA) and 3,3′,4,4′ – Benzophenone tetracarboxylic dianhydride (BTDA) were prepared and their chemical structure transformation after thermal treatment at 350 °C–500 °C was investigated. X‐ray diffraction results revealed an increase in the polymer chain order for all treated PI samples as a consequence of the thermal treatment and chain interaction. TGA analysis showed that the heat treatment promoted different thermal degradation profiles. Electron spin resonance evidenced a large population of free radicals as a result of homogeneous bond cleavage when the thermal treatment was performed at 500 °C. X‐ray photoelectron spectroscopy analysis indicated that the chemical structure transformation not only occurs on the outer surface but also in the sub‐surface layer. These results show that controlled fast thermal treatment can produce materials with specific characteristics and may serve as a general strategy for changing both structural and chemical properties of the polymers. POLYM. ENG. SCI., 58:943–951, 2018. © 2017 Society of Plastics Engineers     

Synthesis of some new 2‐[(2,3‐dihydroinden‐1‐ylidene) hydrazinyl]‐4‐methylthiazole derivatives for simultaneous dyeing and finishing for UV protective cotton fabrics

Several 2‐[1‐(1,2‐dihydroinden‐3‐ylidene) hydrazono]‐5‐aryldiazo‐4‐methyl‐1,3‐thiazoles were synthesized by reaction of 1‐(1,2‐Dihydroinden‐3‐ylidene) thiosemicarbazide with different hydrazonyl chlorides. The products are water insoluble and UV absorbers, expressed UPF‐rating values, and their H₂O/DMF solutions were used in simultaneous dyeing and resin finishing of cotton fabrics. Results obtained show that finishing of cotton samples in presence of any of that dyes, irrespective of dye concentration, brings about an improvement in percent nitrogen, wrinkle recovery angle (WRA), dyeability, and UV protection rating values along with slight decrease of tensile strength (TS) compared with the untreated samples. Irrespective of dye structure, increasing the dye concentration from 0.5 and up to 1.7% results in an improvement in the percent nitrogen, TS and a remarkable improvement in both the dyeability, UPF‐rating values along with slight decrease in WRA and lower fastness properties of the treated fabrics. The treated fabrics was characterized using energy dispersive X‐ray analysis indicating the entrapped dye within the fabric structure. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Annealing of polyacene‐based oligomer synthesized under high pressure

A polyacene‐based oligomer was synthesized by reaction of diphenyldiacetylene under high pressure (pressure: 0.1 GPa; temperature: 250°C; time: 5 h). Annealing of the polyacene‐based oligomer was carried out (temperature: 300–800°C; time: 5 h). Gas analysis, BET surface area measurement, Raman scattering, X‐ray diffraction, elemental analysis, ¹³C‐NMR, and conductivity measurements were performed to characterize the structure of the product. The oligomer was annealed with the appearance of mainly hydrogen. The H/C of the product decreased with increasing annealing temperature. The Raman band is observed at 1610 cm⁻¹ assigned to a doubly degenerate deformation vibration of the carbon hexagonal ring. The additional band observed at 1340 cm⁻¹ is attributed to the size effect. X‐ray diffraction indicated that the product had no sharp peak because of the disordered carbon structure. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 289–292, 1999     

Water‐repellent finishing of cotton fabrics by ultraviolet curing

Cotton fabrics were water‐repellent‐finished by radical ultraviolet curing of silicone and urethane acrylates with different formulations. The fabrics were impregnated with undiluted resins and with toluene solutions or water emulsions. Moreover, cationic ultraviolet‐curable systems were also investigated, such as an epoxy‐functional polysiloxane and mixtures of an epoxy resin with hydroxyl‐containing silicone additives. The gel content and polymerization yield were considered for the ultraviolet‐curing process evaluation. Water‐resistance properties were determined in terms of the contact angle, wettability, moisture adsorption, and water vapor permeability measurements, whereas the morphology and surface composition of treated fabrics were examined with scanning electron microscopy and energy‐dispersive X‐ray analysis. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Microwave‐assisted synthesis of silver nanoparticles on cotton fabric modified with 3‐aminopropyltrimethoxysilane

In this study, silver nanoparticles were synthesized on cotton fabric modified with 3‐aminopropyltrimethoxysilane (APTMS) using sodium citrate as a reducing/stabilizing agent by microwave‐assisted process. The presence of a highly oriented amino‐terminated self‐assembled monolayer and formation of APTMS was demonstrated by an X‐ray photoelectron spectroscopy (XPS) analysis. The silver‐coated cotton fabrics were examined by scanning electron microscopy (SEM) and energy dispersive X‐ray (EDX). UV protection, antistatic, and hydrophobic properties were also evaluated. The results show that silver‐coated fabric modified with APTMS possesses excellent antistatic, UV protection with ultraviolet protection factor (UPF) of 396.5 and superhydrophobic properties with contact angle of 153.2°. APTMS pretreatment improves the adhesive strength between silver coatings and cotton fabric. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3862–3868, 2013     

X‐ray Absorption Spectroscopy Studies of the Room‐Temperature Ferromagnetic Fe‐Doped 6H–BaTiO3

We investigated the effect of annealing temperature on magnetic properties of 2% and 10% Fe‐doped BaTiO₃. To understand the possible structural differences between samples treated at different annealing temperatures, and to correlate them with the magnetic properties, several characterization techniques, such as X‐ray diffraction and X‐ray absorption spectroscopic methods (XANES and EXAFS) were employed. We found that the 2% Fe‐doped BaTiO₃ pseudocubic perovskite is paramagnetic regardless of the heat‐treatment conditions. Initially paramagnetic 10% Fe‐doped 6H–BaTiO₃, treated at 1250°C, became ferromagnetic after additional annealing at higher temperature. We have crystalographically characterized the cation ordering processes in the 6H–BaTiO₃ that occurred during the high‐temperature annealing. The ferromagnetism that is induced in this stage is most probably associated with the observed diffusion processes but it extrinsic character still cannot be fully disregarded.     

Total Oxidation of Chlorinated Hydrocarbons on A1–xSrxMnO3 Perovskite‐Type Oxide Catalysts – Part I: Catalyst Characterization

Thermoanalytical measurements (DTG‐DTA‐MS), X‐ray diffraction (XRD), temperature‐programmed reduction (TPR), redox titration and X‐ray photoelectron spectroscopy (XPS) were used to characterize A_1–xSr_xMnO₃ perovskite catalysts (A = La, Nd, Pr, Di [didymium]). The catalyst samples were investigated before and after interaction with chloromethane in the temperature range between 300 and 650 °C. XRD and TPR measurements revealed the presence of oxide admixtures in samples calcined at 600 and 800 °C, resp., in air. Crystallinity of the samples and the amount of oxide admixtures depend on the kind of A‐site cations. Interaction of the perovskite samples with chlorinated hydrocarbons at reaction temperatures leads to a decrease of the specific surface areas; the perovskite structure is preserved. Redox titration and TPR measurements showed that the Mn(IV) content in the perovskites increases by partial substitution of La by Sr and decreases after interaction with chloromethane.     

Chemical Expansion and Change in Lattice Constant of Y‐Doped BaZrO3 by Hydration/Dehydration Reaction and Final Heat‐Treating Temperature

Knowledge of thermal behavior of electrolyte is important for fuel cell fabrication. In this study, using high‐temperature X‐ray diffraction analysis (HT‐XRD) and thermo‐mechanical analysis (TMA), a systematic investigation of lattice constants was performed on Y‐doped BaZrO₃, which is a promising candidate for electrolyte in protonic ceramic fuel cells. The results revealed that a chemical expansion was observed between 300°C and 450°C during the heating process in HT‐XRD, and was attributed to the dehydration of BZY. Furthermore, it was found that the lattice constants of the samples doped with Y, Sm, Eu, and Dy were larger for the ones finally heat‐treated at 1600°C for sintering than those heat‐treated at 1300°C for synthesizing. The similar behavior was not observed in Sc‐doped samples.     

Effects of shearing and comonomer content on the crystallization behavior of poly(butylene succinate‐co‐butylene 2‐ethyl‐2‐methyl succinate)

Poly(butylene succinate‐co‐butylene 2‐ethyl‐2‐methyl succinate) (PBSEMS) random copolymers were prepared with different comonomer compositions. The effects of shearing and comonomer content on the crystallization behavior of these copolymers were investigated at 80 °C. The thermal and morphological properties of the resulting samples were also discussed. The copolymers showed a longer induction time and a slower crystallization rate with increasing comonomer content. The promoting effect of shear on the overall crystallization behavior was more notable for those copolymers containing more 2‐ethyl‐2‐methyl succinic acid (EMSA) units. The melting temperature of ‘as‐prepared’ poly(butylene succinate) (PBS) was ca. 115 °C, while that of the copolymers varied from 112 to 102 °C. Higher comonomer contents in the copolymers gave rise to lower melting temperatures and broader melting peaks. In addition, the isothermally crystallized samples showed multiple melting endothermic behavior, the extent of which depended on the comonomer content. The copolymers showed different wide‐angle X‐ray diffraction (WAXD) patterns from that of neat PBS, depending on the comonomer content and shear applied during crystallization. With increasing comonomer content, the copolymers crystallized without shearing, showing the shifting of a diffraction peak to a higher angle, while those crystallized under shear did not show any peak shift. Copyright © 2004 Society of Chemical Industry     

Shear‐induced morphology changes in N,N′‐dimethylacetamide/lithium chloride pretreated cellulose

A new mechanochemical treatment was performed on cellulose with the objective of modifying its morphology, reducing its crystallinity, and enabling better dissolution. Cellulose treated with N,N′‐dimethylacetamide (DMAc)/lithium chloride (LiCl) was subjected to shear with natural rubber as the carrier and shear‐transfer medium. When cellulose was subjected to such a mechanochemical treatment, significant changes in its surface morphology and a decrease in crystalline index were observed. The dissolution of the mechanochemically treated cellulose samples in DMAc/LiCl was found to be better compared with the dissolution of samples subjected to either mechanical shear or the chemical action of DMAc/LiCl independently. Chemical interactions between DMAc/LiCl and cellulose were enhanced synergistically under shear‐induced deformation. When shear alone was used in the absence of a DMAc/LiCl treatment, changes in the morphology, crystalline index, and dissolution were found to be negligible. The shear‐induced cellulose samples were characterized with Fourier transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, and thermogravimetric analysis. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44809.     

Creating a Protective Shell for Reactive MoSi2 Particles in High‐Temperature Ceramics

Alumina encapsulated molybdenum silicide (MoSi₂) intermetallic particles were synthesized using a simple precipitation method followed by calcining at temperatures of 800°C–1000°C, to prevent the premature oxidation of MoSi₂ at high temperatures. The shell composition and the influence of the calcining temperature on microcapsule integrity were investigated by means of X‐ray photoelectron spectroscopy, X‐ray diffraction, scanning electron microscopy, and thermogravimetric analysis. The results demonstrate that the composition and the mechanical stability of the alumina shell can be tuned by the annealing temperature. After calcining at 800°C and 850°C the alumina shell remains intact. Calcining at higher temperature promotes the formation of mullite, which leads to cracking of the shell. However, when annealed at 1000°C for 24 h these cracks were filled with mullite and preserved the molybdenum silicide particles. Furthermore, the mechanical stability of the shell was improved by applying an intermediate calcining treatment at 450°C prior to the annealing process at 1000°C.