Synthesis,characterization, and properties of flexible magnetic nanocomposites of cobalt ferrite–polybenzoxazine–linear low‐density polyethylene

A simple method for the preparation of magnetic nanocomposites consisting of cobalt ferrite (CF; CoFe₂O₄) nanoparticles, polybenzoxazine (PB), linear low‐density polyethylene (LLDPE), and linear low‐density polyethylene‐g‐maleic anhydride (LgM) is described. The composites were prepared by the formation of benzoxazine (BA)–CF nanopowders followed by melt blending with LLDPE and the thermal curing of BA. The composites were characterized by X‐ray diffraction, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy, universal testing machine measurement, and vibrating sample magnetometry. The composites consisting of LLDPE, PB, and LgM (47.5L–47.5PB–5LgM) exhibited a higher tensile strength (23.82 MPa) than pure LLDPE and a greater elongation at break (6.11%) than pure PB. The tensile strength of the composites decreased from 19.92 to 18.55 MPa with increasing CF loading (from 14.25 to 33.25 wt %). The saturation magnetization of the composites containing 33.25 wt % CF was 18.28 emu/g, and it decreased with decreasing amount of CF in the composite. The composite films exhibited mechanical flexibility and magnetic properties. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The PANOPTIC Camera: A Plenoptic Sensor with Real-Time Omnidirectional Capability

A new biologically-inspired vision sensor made of one hundred “eyes” is presented, which is suitable for real-time acquisition and processing of 3-D image sequences. This device, named the Panoptic camera, consists of a layered arrangement of approximately 100 classical CMOS imagers, distributed over a hemisphere of 13 cm in diameter. The Panoptic camera is a polydioptric system where all imagers have their own vision of the world, each with a distinct focal point, which is a specific feature of the Panoptic system. This enables 3-D information recording such as omnidirectional stereoscopy or depth estimation, applying specific signal processing. The algorithms dictating the image reconstruction of an omnidirectional observer located at any point inside the hemisphere are presented. A hardware architecture which has the capability of handling these algorithms, and the flexibility to support additional image processing in real time, has been developed as a two-layer system based on FPGAs. The detail of the hardware architecture, its internal blocks, the mapping of the algorithms onto the latter elements, and the device calibration procedure are presented, along with imaging results.     

Acoustical absorptive properties of spunbonded nonwovens made from islands-in-the-sea bicomponent filaments

In this paper, we report on the acoustical absorptive behavior of spunbonded nonwovens that contain bicomponent islands-in-the-sea filaments. Nylon 6 (PA6) and polyethylene were used as the islands and the sea polymers, respectively. Spunbonded webs made with islands-in-the-sea bicomponent filaments with island counts of 1, 7, 19, 37, and 108 were produced at the Nonwovens Institute’s pilot facilities at NC State University. The filaments were fibrillated by hydroentangling, where high-speed water jets were used to fibrillate the fiber and ‘free’ the islands. The influence of the number of islands on acoustical absorptive behavior of the spunbonded nonwovens was investigated. A comparison of acoustical absorptive properties of multi-layer islands-in-the-sea nonwoven and high loft nonwoven was also performed to evaluate the potential use of spunbonded nonwovens made from islands-in-the-sea bicomponent filaments in place of bulky fibrous sound absorbers. Results have shown that multi-layer 108 nonwoven islands were better acoustic absorbers at nearly half of the frequency range. Spunbonded nonwovens made from islands-in-the-sea bicomponent filaments can be a good alternative in applications where there is desire to replace bulky fibrous sound absorbers.     

A comparative study of lean and agile manufacturing with a related survey of current practices in the UK

In response to changing success factors and environmental pressures, companies are aspiring to break out of mass production and become lean or agile. Whereas performance enhancements of lean practices have been demonstrated, it is now the case that markets have become increasingly characterized by turbulence, a situation in which reliance on lean practices is insufficient, and that survival requires adoption of agile practices. As a result, a comparative study of lean and agile manufacturing with a related survey of current practices in the UK was carried out, the results of which is presented in this paper. The paper explored the threats to lean and the drivers of agile manufacturing. Using data from a questionnaire survey, four hypotheses were tested, which was indicative of the benefits of agile manufacturing. In contrast to their lean counterparts, agile companies paid attention to a wider range of competitive capabilities. They therefore had a lower range of mean scores on competitive capabilities. Independent sample tests of significant difference in business performance measures revealed that the agile companies consistently outperformed their lean competitors on all business performance measures studied. In addition, a wider range of competitive capabilities and performance measures of the agile companies correlated significantly and positively whilst such correlation was observed for only a narrow range of capabilities and performance measures for lean companies. The results suggest that competing simultaneously on multiple competitive capabilities enhance performance better than a rather narrow focus on cost and quality.     

Factors influencing the crushing strength of some Aegean sands

Engineering properties of sands mainly depend on the integrity of the particles, which in turn has a strong bearing on their crushing strength. Seven different Aegean sands were tested for mineralogy, particle shape, size and specific gravity and the influence of aspect ratio, particle composition, particle shape and size on the crushing strength was examined. As the Aegean sands have a small range of sphericity and roundness, crushing strength tests were also performed on five Anatolian sands. A multiple regression analysis was carried out and an equation proposed to determine the crushing strength value of the Aegean sands. The computed values were found to be in good agreement with those obtained from the experimental investigations. It is concluded that the equation is sufficiently accurate to be a useful, time- and cost-effective way of obtaining crushing strength estimations at the preliminary stage of site investigations.     

Functional polyamides. 3. Synthesis and chelating properties of a new poly(amide thioether)

Polymerization of β,β′-(ethylenedithio)dipropionitrile

1 IUPAC name: 4,7-dithiadecane dinitrile.

with formaldehyde in the presence of sulfuric acid was carried out in order to permit the synthesis of polymides containing thioether groups. The obtained poly(amide thioether)s were characterized; they coordinate mercury (II) with a high degree of selectivity.     

Preparation of multiphase block copolymers by redox polymerization process

Redox polymerization of methylmethacrylate (MMA) using Ce(IV) with poly(oxyethylene) having azo and hydroxy functions was carried out to yield methylmethacrylate-ethylene glycol block copolymers with labile azo linkages in the main chain. These prepolymers were used to initiate the radical polymerization of styrene through the thermal decomposition of the azo group, resulting in the formation of multiblock copolymers. Successful blocking has been confirmed by fractional precipitation, a strong change in the molecular weight distribution and spectral measurements.     

Deposition and Characterization of Si Substituted Cu2ZnSnS4 Thin Films

Silicon - The influence of the Si substitution ratio on the structural, morphological, and optical properties of Cu2ZnSnS4 (CZTS) thin films was examined. The Cu2Zn(SixSn1–x)S4 thin films...     

Polyurethaneurea–silica nanocomposites: Preparation and investigation of the structure–property behavior

Nanocomposites consisting of thermoplastic polyurethane–urea (TPU) and silica nanoparticles of various size and filler loadings were prepared by solution blending and extensively characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), thermal analysis, tensile tests, and nanoindentation. TPU copolymer was based on a cycloaliphatic diisocyanate and poly(tetramethylene oxide) (PTMO-2000) soft segments and had urea hard segment content of 20% by weight. TPU/silica nanocomposites using silica particles of different size (29, 74 and 215 nm) and at different loadings (1, 5, 10, 20 and 40 wt. %) were prepared and characterized. Solution blending using isopropyl alcohol resulted in even distribution of silica nanoparticles in the polyurethane–urea matrix. FTIR spectroscopy indicated strong interactions between silica particles and polyether segments. Incorporation of silica nanoparticles of smaller size led to higher modulus and tensile strength of the nanocomposites, and elastomeric properties were retained. Increased filler content of up to about 20 wt. % resulted in materials with higher elastic moduli and tensile strength while the glass transition temperature remained the same. The fracture toughness increased relative to neat TPU regardless of the silica particle size. Improvements in tensile properties of the nanocomposites, particularly at intermediate silica loading levels and smaller particle size, are attributed to the interactions between the surface of silica nanoparticles and ether linkages of the polyether segments of the copolymers.