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The integrated THz pattern over any MMIC appears to be a good opportunity to enclose calibration kit suitable for accurate measurements. An original technology based on polymer has been developed. Sub-millimeter single-mode conductor-backed coplanar waveguides using benzocyclobutene polymer and interconnecting via between ground planes are processed and measured up to 760 GHz. The experimental performances show good agreement with analytical and numerical modeling. A two-tier Thru-Reflect-Line correction and a square root of Thru de-embedding are applied to extract the attenuation factor of about 3 dB/mm at 600 GHz, the relative phase velocity to light of about 0.716 and the characteristic impedance around 50 Ω. The fundamental propagating mode remains unique in this wide frequency range, enabling this technological to be integrated over existing circuit for THz applications. The loss performance of the coplanar waveguide ranges in the state-of-the-art opening the road for fully integrated THz circuits. [ABSTRACT FROM AUTHOR]

In this paper, the experimental paradigm of cognitive behaviors to study the cognitive activities in the contiguous sense cognition of the tested linen clothing is introduced. The experimental program is written with E-Prime 2.0, while the expression of experimental stimulus material is realized with the developed dressing contiguous sense measurement device, which output the senses of urtication, roughness and smoothness among the fabric contiguous sense. Changing the relative force for the contact between fabric and human skin, the dressing contiguous sense is tested in different contiguous force conditions. The result shows that, with the increase of relative contiguous force, the evaluation value for the sense of urtication is increase, the value for the roughness sense is also increase, but that for the smoothness sense is decrease.

In this study, the aim was to examine the effects of three different compatibilizers on the recycled polyethylene/ thermoplastic starch (r-LDPE/TPS) blends which are used in producing garbage bags. Polyethylene-Grafted-Maleic Anhydride (PEgMAH), maleic-anhydride modified ethylene propylene rubber (EPMgMAH) and ethylene maleic anhydride copolymer (PEMAH) were selected as the compatibilizers. r-LDPE/TPS blends with or without compatibilizer were prepared by using a twin screw extruder and characterized by means of mechanical, thermal, structural and morphological analyses. It was found that tensile strength values increased with the addition of PEgMAH but decreased with the addition of EPMgMAH. Elongations at break values of the r-LDPE/TPS blends were significantly improved by using PEgMAH and EPMgMAH. Tm and Tc values have slightly affected by the compatibilizer usage in the DSC analysis. In addition, the better interfacial interaction was observed for the compatibilized blend with the PEgMAH and EPMgMAH during the SEM analysis. It was concluded that PEgMAH and EPMgMAH showed mainly changed results in elongation at break values and this is the important parameter in the packaging industry.

We report the preparation of pore expanded and sulfonic acid functionalized mesoporous silica catalysts by using different kinds of swelling agents such as 1,3,5-trimethyl benzene (TMB), n-decane (D), n-tridecane (TD), and n-hexadecane (HD) at two different ratios of swelling agent/surfactant. Non-swelled mesoporous silica catalyst, SBA-15-SO3H, was also prepared for comparison. The performance of the sulfonic acid functionalized solid acid catalysts by using one-pot synthesis procedure was evaluated in terms of their catalytic activity in the esterification of propionic acid with methanol. The catalysts have been characterized by X-ray diffraction to investigate the phase transition between the hexagonally packed arrangement of cylindrical pores and mesocellular silica foams (MCF), and N2 adsorption/desorption technique in terms of pore size and distributions. It was concluded from the XRD and N2 adsorption/desorption analyses that hexagonally packed and cylindrical pore structure is maintained only for low ratio of swelling agent/surfactant and the increase of the dimension of a template micelle is accompanied by an increase in structural disruption, which was attributed to the phase transition from highly ordered hexagonal arrangement to mesocellular foam (MCF) phase with large nodded pore structures rather than cylindrical pores. Among the different swelling agents, TMB and D were found to be effective for the increase in pore diameter (up to 8 and 7.8 nm), whereas, TD and HD (6.6 nm) are effective to maintain the ordered X-ray diffraction patterns resulting mesoporous materials without giving enlargement of pore diameter in comparison with TMB and D. Pore expanded catalysts, SBA-15-SO3H-TMB-0.1 and SBA-15-SO3H-D-0.1, exhibit 68 and 43% enhancement in turnover frequency toward propionic acid methanol esterification, respectively, over non-swelled SBA-15-SO3H, despite possessing similar acid strengths. The increased activity especially for SBA-15-SO3H-TMB-0.1 and SBA-15-SO3H-D-0.1 likely reflects the accessibility to the active sulfonic acid sites as well as acidity.

Electrospinning is an experimental method of the polymer super thin fibres formation using the electrostatic field. The distribution of electrostatic field affects the effectiveness of the electrospinning. In order to analyse the electrostatic field for given technological parameters the 3-D computer model of an electrospinning device must be applied.

Since their discovery by Iijima in 1991 [1], carbon nanotubes have sparked unwavering interest among researchers all over the world. This is due to the unique properties of carbon nanotubes (CNTs). Carbon nanotubes have excellent mechanical and electrical properties with high chemical and thermal stability. In addition, carbon nanotubes have a very large surface area and are hollow inside. This gives a very broad spectrum of nanotube applications, such as in combination with polymers as polymer composites in the automotive, aerospace or textile industries. At present, many methods of nanotube synthesis are known [2, 3, 4, 5, 6]. It is also possible to use carbon nanotubes in biomedical applications [7, 8, 9, 10, 11, 12, 13, 14], including the destruction of cancer cells using iron-filled carbon nanotubes in the hyperthermia process. Computer modelling results of Fe-CNTs induction heating process are presented in the paper. As an object used for computer model creation, Fe-CNTs were synthesized by the authors using CCVD technique.

Electrospinning is a very interesting method that allows the fabrication of continuous fibers with diameters down to a few nanometers. This paper presents an overview of electrospinning systems as well as their comparison using proposed three-dimensional parameterized numerical models. The presented solutions allow an analysis of the electric field distribution.

Abstract Macromolecular modifications of poly(etherketoneketone) (PEKK) copolymer prepared from diphenyl ether (DPE), terephthalic acid (T) and isophthalic acid (I) with a T/I ratio of 60/40 have been investigated above its melting temperature by gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and rheological measurements to assess the evolution of PEKK matrix during composite consolidation step. We mainly focused in this study on anaerobic conditions, i.e. degradation under nitrogen or in lack of oxygen. During exposure, thermal degradation leads to an increase of weight average molar mass M w and viscosity which is typical to crosslinking/branching mechanism as already observed for PEEK in the literature. However, thanks to GPC measurements, it appears that a chain scission mechanism occurs in the same time related to a constant number average molar mass M n. Crosslinking kinetics are identified at several temperatures between 320 and 400 °C with rheological measurements from a kinetic scheme governing the crosslinking mechanism. At last, the influence of the crosslinking process on PEKK crystallization is investigated. The final crystallinity and crystallization kinetics decrease with crosslinking due to branching of macromolecular chains. Highlights • Anaerobic degradation of PEKK results in crosslinking and chain scission processes. • Crosslinking vs chain scission is characterized by molar mass and viscosity. • Crosslinking is predominant over chain scission. • Final crystallinity and crystallization kinetics decrease with degradation time. [ABSTRACT FROM AUTHOR]

The structure and morphology of polymers are significantly altered upon exposure to high energy gamma irradiation either through bond breakage i.e. scission or cross-linkage. The present article reports the influence of gamma radiation (1–20 kGy) on the distribution of molecular weight and porosity of the films prepared using irradiated and unirradiated poly-[ethylene oxide] (PEO) powder. The PEO films exhibit pore dimension in the range of 20–500 nm. Selective irradiation is capable of tailoring the pore-size and reducing the multimodal trait to uni-or bimodal upon high energy perturbation. The porosity of PEO films is determined from both 2D-pore surface calculation from SEM images and compared with 3D-BET porosity. Correlation is established among dielectric constant (ε′) and porosity. The magnitude of ε′ increases sharply towards low frequency due to electrode polarization effects. Relaxation time is found to be highest and comparable for 1 and 10 KGy. With increase in irradiation dose, scission is predominant, owing to which smaller polymer fragments are produced which are able to follow fast frequency regime and thereby relax at lesser time. [ABSTRACT FROM AUTHOR]

Natural resources have been decreasing with the large expansion of the world's population. In order to supply raw material for production, new recycling approaches should be developed for waste materials. Worn shoes is one of the most common waste products that can be recycled for this purpose. According to the record, shoes are very complex products, as they can be produced from forty different materials, like leather, rubber, polymers etc. Especially the bottom layers of the shoes are made from sound absorbing materials like polyurethane, thermoplastic rubber and PVC. Because today's technology is not able to separate these materials from each other during recycling, they should be used in a homogenised state. Thus these parts were shredded into small granules and mixed. PU binder and hot press were used to obtain samples for tests. In this paper sound absorption, sound isolation, vibration isolation and thermal insulation properties of the tread mixture are investigated. In addition to that, the mechanical properties of the material were also investigated by measuring the compression strength of the material. [ABSTRACT FROM AUTHOR]

The aim of this study is the investigation of the effects of an intumescent system, consisting of ammonium polyphosphate (APP), as a flame retardant additive, pentaerythritol (PER), as a carbonic agent, and nanoclay, as a synergistic agent, on the flame retardancy of plasticized poly(lactic acid) (PLA). In accordance with this purpose, plasticized and flame retarded PLA with APP compound was prepared and used as a control sample. Nanoclay loading levels were changed between 3 and 10 wt.% in the PLA/APP/PER samples. Samples were produced using extrusion and injection molding techniques. The morphological, thermal, mechanical and flammability properties were studied. The flammability evaluation was performed using limiting oxygen index and vertical burning (UL-94) tests. The obtained limiting oxygen index value was up to 32.9 and UL-94 grade could pass V-0 for samples, containing 3 wt.% of nanoclay. However, increasing nanoclay amount has enhanced the burning time of the sample. The thermal behaviors of the samples were characterized by differential scanning calorimetry. It was shown, that PER incorporation did not significantly change the percentage crystallinity value. The increasing nanoclay loading levels reduced the degree of crystallization. Elongation at break value of sample, containing 5 wt.% of nanoclay, increased by 28%, compared to the control sample. [ABSTRACT FROM AUTHOR]

The paper presents results of the investigation of structure relaxation and thermal properties of PE-80 and PE-100 polyethylene hot-tool butt welds. It was found that a weld with the re-crystallized crystalline structure is formed during the welding of dissimilar types of polyethylene. It is shown that within a long period (1 year) the relaxation occurs not only in amorphous but also in the crystalline phase (crystalline α-form transforms into mixed αβ-form), with respective changes in polyethylene properties. [ABSTRACT FROM AUTHOR]

Interactions of Poly [-Ethylene Oxide] [PEO of molecular weight 10] and gamma irradiation with variable doses (1-30 kGy) are studied for the thermal, crystalline and structural properties using differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) technique. Two states of PEO, viz. powder (P-S-series) and methanol solution (P-L-series) are subjected to irradiation and then cast into uniform films at room temperature. DSC results have revealed steady increment of crystallinity up to 20 kGy for P-S-series which starts reducing till 30 kGy. Conversely, P-L-series shows much enhanced crystallinity retained within low irradiation regime of 7 kGy, followed by sharp declining trend till 30 kGy. DSC is employed to study the influence of gamma radiation on multiple kinetic processes in an isoconversional melting of PEO using Friedman differential analysis. This study illustrates the variation of activation with degree of conversion of melting for different doses on irradiated PEO powder and methanol solution. Gamma irradiation is found to generate newer functional groups which are also established from FTIR study. Presence of -C=O and -C=C- groups in FTIR spectra reveals the predominance of scission during air assisted irradiation. FTIR spectra also prove higher degree of cross-linking in irradiation of methanol solution. The observations of DSC and FTIR are correlated with polymer microstructures. Therefore, selective irradiation dose can effectively be utilized to tailor the properties of PEO depending upon the exposed powder or methanol solution of polymer. [ABSTRACT FROM AUTHOR]

During the last two decades, the development of laboratory scale extreme ultraviolet sources has been intensified due to growing interest in use of extreme ultraviolet sources photons for various applications in science and technology. In this study, we present a potential application of extreme ultraviolet sources surface modification of polymers to be used as substrates for cancer cell identification. The surface modification of polytetrafluoroethylene (PTFE) polymer samples was performed by a lab scale compact laser-plasma extreme ultraviolet sources source based on a double-stream gas-puff target. The gas target was irradiated with a 3 ns/0.8 J Nd:YAG laser pulse at 10 Hz with 50 and 300 pulses. HCV29 non-malignant transitional epithelium and T24 bladder cells adhesion and proliferation studies on pure and extreme ultraviolet sources modified PTFE surfaces were performed. The extreme ultraviolet sources modified surfaces demonstrated regular increase in cancer cell proliferation comparing to pristine sample. Initial results indicate that extreme ultraviolet sources treated substrates can facilitate the identification of cancer cells. [ABSTRACT FROM AUTHOR]

Nanofibers have enormous applications in various areas such as environment, new energy, National security, filtration and so on. In this paper, polyvinyl alcohol micro-porous webs with excellent properties and highly filtration efficiency are fabricated using electrospinning. The solvent chosen is anhydrous formic acid and formic acid with concentration of 88 wt%. Filtration efficiency of fabrics strongly depends upon fiber size and pore size. A mathematical relationship between filtration efficiency and pore size is suggested. [ABSTRACT FROM AUTHOR]

Polypropylene (PP) and polyimide (PI), which belong to entirely different classes of polymers, are irradiated by Co-60 gamma radiation under similar doses and similar conditions in the dose range varying from 57.6 to 230.4 kGy. The radiation responses of these two polymers are analyzed by various characterizations such as Fourier transform infrared, UV–visible, energy-dispersive spectroscopy, X-ray diffraction, scanning electron microscopy and contact angle. PP shows substantial modifications in its structure and properties while in the same dose range, PI shows remarkable stability. These two different responses are interpreted in terms of physicochemical structure and properties of these polymers. [ABSTRACT FROM PUBLISHER]

Zn-doped talc were synthesized under hydrothermal conditions at constant reaction time and pressure of 160 hours and 2 kbar respectively, at three different temperatures (300, 500 and 650 °C) with pH-values of 5 and 7. The starting materials and run products were characterized by X-ray powder diffraction (XRPD), scanning electron microscopy with annexed energy-dispersive spectrometry (SEM-EDS), differential scanning calorimetry thermogravimetric analysis (DSC-TG) and Fourier transform infrared (FT-IR). The results showed that the temperature, pH-value of the reaction mixture and amount of zinc in the starting mixture affected the growth of the Zn-doped talc. When synthesized at low temperature talc presents low crystallinity, flawed morphology but higher content in zinc in its lattice. A thermal treatment at, or above 500 °C allowed a significant flaw reduction in talc morphology, a higher crystallinity and a lower content in dopant. When large amounts of Zn were present in the starting mixtures, Zn-doped talc grew small in size and poorly shaped. The effect of Zn doping on some chemical/physical characteristics of the synthesized talc was also discussed. [ABSTRACT FROM AUTHOR]

By irradiating two macromolecules, namely polypropylene and polyimide having notably different physicochemical properties, with the same radiation under identical conditions, it is inferred that the mechanical and thermal degradation or the stability of the macromolecule exposed to high-energy radiation strongly correlates with its physicochemical structure. This is well supported by two distinct characterizations, namely stress–strain analysis and thermogravimetric analysis. [ABSTRACT FROM AUTHOR]

Adhesion of the coatings to the substrate plays a vital role in improving mechanical properties of sol-gel coatings especially when deposited on plastics. In the present study, an attempt was made to study the effect of atmospheric air plasma surface activation on the adhesion of sol-gel nanocomposite coatings on polycarbonate substrate. The sol was synthesized by the hydrolysis and condensation of an epoxy silane (3-Glycidoxypropyl trimethoxy silane) along with titanium tetraisopropoxide. Coatings were deposited on 100?×?100?mm substrates by spray coating and subsequently subjected to UV curing followed by thermal curing at 130?°C for 1?h. One set of the substrates was subjected to atmospheric air plasma surface pretreatment prior to coating deposition. Coating thickness, adhesion as well as mechanical properties like pencil hardness, scratch resistance and taber abrasion resistance were evaluated for coatings deposited over plasma-treated and -untreated surfaces. It was found that plasma surface pretreatment has improved the pencil hardness from H to 2H and adhesion of coatings from 2B to 4B. Results obtained from the above experiments were discussed on the basis of surface modification using plasma pretreatment. [ABSTRACT FROM PUBLISHER]

Hydrophilic cotton fabrics were exposed by low-pressure DC glow discharge plasma in argon atmosphere. The influence of different operating parameters such as treatment time, discharge potential, and operating pressure on the chemical and physical properties of the cotton fabrics is studied. Surface analysis and characterization of the plasma-treated cotton fabrics is performed using vertical wicking experiments, X-ray photoelectron spectroscopy, scanning electron microscopy, and weight loss measurements. The cotton fabrics show a significant increase in wicking behavior, an effect that increases with increasing treatment time. Results also show that low-pressure DC glow treatment leads to surface attrition of the cellulose fibers, accompanied by an incorporation of oxygen-containing groups (C–O, C=O, O–C–O, and O–C=O) on the cotton fibers. [ABSTRACT FROM PUBLISHER]

The induced modifications of the optical properties in UV-irradiated Makrofol-E with different wavelengths were investigated. Makrofol-E samples were irradiated by UV of wavelengths 254, 302, and 365 nm for different durations. It was found that Makrofol-E shows substantial modifications in its optical characteristics upon exposure to UV of wavelengths 302 and 254 nm, but no modifications were observed at 365 nm. UV-irradiated Makrofol-E with wavelengths 254 and 302 nm exhibits shoulder bands at 297 nm in UV–visible spectra. For an exposure time less than 20 h, the band absorbance strengths depend on the exposure time and approximately increases linearly, but for prolonged exposure times, the band absorbance strengths become almost saturated. The optical energy band gaps obtained from the direct and indirect allowed transition in K-space. Both of them decrease with the increase in exposure time for wavelengths of 254 and 302 nm. Urbach's energy increases with increase in the exposure time for both wavelengths of 254 and 302 nm. The number of carbon atoms in a cluster increases with the increase in the exposure time. [ABSTRACT FROM AUTHOR]

A radiation resistant optical fiber with a high birefringence is fabricated on the basis of nitrogen-doped silica glass using the PANDA technology and studied. The loss in this fiber for an absorbed @[gamma]-radiation dose of 2–10 kGy does not exceed 5–10 dB/km, which is an order of magnitude lower than that of standard telecommunication fibers with a germanium silicate core. [ABSTRACT FROM AUTHOR]

This article describes our attempts since 1996 to systematically design and synthesize monomers and corresponding polymers for nuclear track detection. So far more than 15 homopolymers/copolymers have been prepared and tested by us for this purpose. Some of these polymers show better track detection characteristics vis-á-vis commercially available poly allyl diglycol carbonate (PADC) track detectors. [ABSTRACT FROM AUTHOR]

Temperature dependent electrical conductivity of the polyaniline-sulfonated poly(arylene ether sulfone) with 35 mol percent sulfonation (PANI-BPS35) composite films were investigated in the temperature range of 80–380 K. These composite films showed semiconductor behavior with the exponential variation of inverse temperature dependence of electrical conductivity. Calculated Mott’s parameters showed that variable range hopping mechanism is the dominant transport mechanism for the carriers in low temperature region. Photoconductivity of the PANI-BPS35 composite films having 10, 20, and 40 weight percent conductive filler under various illumination intensities was also studied. Photocurrent of the composite films increased with increasing both polyaniline weight fraction and temperature. Finally, the effect of doping on both electrical conductivity and the photoconductivity of the composite films was investigated. [ABSTRACT FROM AUTHOR]

Layers made from soluble low molecular weight polythiophene PQT-12 with low polydispersity exhibit a highly ordered structure and charge-carrier mobilities of the order of 10−3 cm2/(V s), which we attribute to its proximity to monodispersity. We propose that polydispersity is a decisive factor with regard to structure formation and transport properties of soluble low molecular weight polythiophenes. [ABSTRACT FROM AUTHOR]

Electron microscopy is an important characterization technique for the study of textile fibre as it gives more information on fabric wear, nature of fibre fracture, chemical degradation, abrasion, fatigue and many others. Electron Probe Micro Analyzer (EPMA) micrographs of virgin and some neutron-irradiated samples (graphite coated) are discussed. The filament diameter, D, of virgin PET fibre obtained from EPMA study was 12.5 μn. The surface topography of single filament distinctly reveals the core and sheath parts of the filament. The core diameter of the virgin fibre was estimated to be 1.43 μm. The fibre irradiated at fluence 1 × 1012 n/cm2 shows radiation induced sphere like polymer balls or spherulites of diameter 2.27 μm in the expanded core region. Due to irradiation, the sheath area crosslinks with expanded core region, which may be responsible for increase of strength and hardness of the polymer materials. Moreover, the micrograph at 3000 X magnifications clearly shows that there is no preferred orientation of the polymer in any direction confirming the isotropic nature of the sample. [ABSTRACT FROM AUTHOR]

Pulsed laser deposition (PLD) at 248 nm in ultra high vacuum was used to produce thin poly(methyl methacrylate) (PMMA) and poly(ethyl methacrylate) (PEMA) films. The ablation and deposition mechanisms were found to be similar in both systems. Having the same backbone, these polymers differ in the size of their polar side groups leading to changes in their dynamics. Studies of the relaxation processes were performed using mechanical torsion and bending spectroscopy by means of a double-paddle oscillator (DPO) and an in-situ plasma plume excited reed (PPXR), respectively. A strong increase of the mechanical damping was observed during annealing of the polymer films well above the glass transition temperature T g, while in-situ X-ray measurements did not reveal any structural changes. For PEMA, the glass transition temperature T g=335 K and the main absorption maximum appear at lower temperatures compared to PMMA ( T g=380 K), allowing one to measure the mechanical properties in a much wider range above T g. [ABSTRACT FROM AUTHOR]

A method for preparation of homogeneous samples of metal-phthalocyanines doped with alkaline metals was developed. Polycrystalline samples of zinc phthalocyanines doped with sodium, potassium, and rubidium atoms were investigated. We measured the temperature dependence of ESR spectra of prepared samples and studied their composition and structure. It is shown that their magnetic properties depend strongly on the degree of doping as well as on the subsequent grinding and annealing. [ABSTRACT FROM AUTHOR]

The calculated optical characteristics and the technology for the structure formation of multichannel optical splitters are presented. The splitters are based on planar optical waveguides made of silica glass obtained via microwave plasma chemical deposition. Multimode splitters of the 16 × 16 type for the fiber optic data-transmission systems are produced with the use of the planar waveguides. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, polyethylene terephthalate (PET) films are modified by a dielectric barrier discharge (DBD) in a helium/air mixture at medium (6.6 kPa) and atmospheric pressure. Surface analysis and characterization of the plasma-treated PET films is performed using contact angle measurements, X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM). The polymer films, modified with the DBD at medium and atmospheric pressure, show a significant decrease in water contact angle due to the incorporation of oxygen-containing groups, such as C–O and O–C=O. Results also show that the surface treatment is uniform at micron scales, despite the fact that the discharge consists of a series of microdischarges. It is shown that at low energy densities (<±200 mJ/cm2), plasma treatment at medium pressure is more energy-efficient in incorporating oxygen functionalities than plasma treatment at atmospheric pressure. This effect could be induced by the larger diameter of the microdischarges at medium pressure than at atmospheric pressure (factor 3.92) and/or by the lower quenching of atomic oxygen in three-body collisions at medium pressure. The ageing behaviour of the plasma-treated PET films during storage in air is also studied in this paper. XPS results reveal that during the ageing process the induced oxygen-containing groups re-orientate into the bulk of the material. In this paper, it is shown that the ageing behaviour of the PET films is independent of the operating pressure used during plasma treatment. [Copyright &y& Elsevier]

For the first time, the properties of a single-polarization microstructured fiber exhibited over a broad spectral range have been numerically simulated. The simulation was performed via the multipole method adapted to asymmetric structures. A structure with the highest values of birefringence and dichroism known to date has been proposed and investigated. [ABSTRACT FROM AUTHOR]

A new method for calculating the radiation loss and chromatic dispersion of leaky modes propagating in microstructured (holey) optical fibers (MOFs) with circular air-filled channels is proposed and implemented numerically. It is shown that the results are in good agreement with both the known numerical data and with the experimental data obtained for two types of fabricated MOFs that contain, respectively, 30 and 60 channels. [ABSTRACT FROM AUTHOR]