Metal–Organic Framework Material Inhibits Biofilm Formation of Pseudomonas aeruginosa

An 85% reduction in the bacterial attachment of Pseudomonas aeruginosa is achieved using a water‐stable metal–organic framework (MOF) blended with chitosan. These materials demonstrate this reduction in bacterial adhesion in the first 6 h and maintain it over the full 24 h exposure period, a remarkable impediment of biofilm formation to achieve, given the strength of this bacteria strain. The films elicit the same inhibitory effect after a second round of experiments, suggesting reusability of the materials. Characterization of the films by powder X‐ray diffraction, attenuated total reflectance‐IR, and scanning electron microscopy supports retention of the MOF structure within the chitosan matrix. The extensive control experiments employed in this study isolate the observed biological effects to the synthesized films, and not to possible leachates from the films. This presents the first account of using a water‐stable MOF within a polymer as a means to achieve an antibacterial surface by demonstrating an 85% reduction in bacterial attachment of Pseudomonas aeruginosa.     

Single-shot dense depth sensing with frequency-division multiplexing fringe projection

In structured light illumination (SLI) systems, multi-shot fringe patterns can reach higher precision than a single-shot fringe pattern. However, multi-shot methods are not suitable for dynamic scenes while single-shot ones are limited in the measurement accuracy. In this paper, a novel single-shot depth sensing method with frequency-division multiplexing (FDM) framework is proposed. To achieve a simultaneous casting, two fringe patterns with coprime periods are modulated into a single pattern. The method of fringe pattern extraction is similar to the demodulation in communication systems. The Gabor filter is adopted to get the phase information in the pattern, and the coprime theorem is used to solve the phase ambiguity. Quantitative and qualitative evaluations have proved that our method achieves higher accuracy in depth sensing compared with the Kinect v1 and ToF camera. In addition, benefiting from the single-shot pattern, our method is suitable for dynamic scenes.     

Effect of interfacial enhancing on morphology,mechanical, and rheological properties of polypropylene‐ground tire rubber powder blends

In this work, polypropylene (PP)‐ground tire rubber (GTR) blends are prepared by means of melt‐extrusion process using a co‐rotating twin screw extruder. The influences of types of compatibilizers and crosslinkers on the interfacial interaction state, mechanical and rheological properties of PP‐GTR blends are investigated systematically. Particularly, quantitative nano mechanic technique of atom force microscope was employed to examine the change in thickness of the interfacial transition layer between PP and GTR phase with variety of compatibilizer and crosslinker types. Results indicated that styrene‐b‐poly(ethylene‐ethylene/propylene)‐b‐polystyrene (SEEPS) and peroxide are optimal compatibilizer and crosslinker for interfacial interaction enhancement, respectively. The resultant PP‐GTR blend possesses tensile strength of 14.5 MPa, elongation at break of 307%, and permanent set of 16%. It was expected that reaction activities of the crosslinker with GTR and SEEPS would have a significant influence on the agglomeration of GTR particles and the interaction between PP and GTR phase. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45354.     

Fabrication of highly monodisperse CeO2@poly(methyl silsesquioxane) microspheres and their application in UV‐shielding films

Highly monodisperse CeO₂@poly(methyl silsesquioxane) (PMSQ) microspheres were successfully prepared by a facile chemical precipitation technique. The structures and properties of CeO₂@PMSQ were analyzed by Fourier transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy techniques. We confirmed that the PMSQ microspheres were uniformly coated by CeO₂ nanoparticles, with about an 8 nm crystallite diameter. Then, CeO₂@PMSQ was incorporated into a poly(vinyl alcohol) (PVA) matrix to fabricate PVA/CeO₂@PMSQ composite films by the casting of homogeneous solutions. The thermal and optical properties of the composite films were investigated by thermogravimetric analysis and UV–visible spectroscopy. The results show the high UV‐shielding efficiency of the composites: for a film containing 2.5 wt % CeO₂@PMSQ microspheres, about 80% UV light at wavelengths between 200 and 360 nm was absorbed, whereas the optical transparency in the visible region still remained very high. The addition of CeO2@PMSQ microspheres improved the thermal stability of the PVA films. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45065.     

Experimental study of the effect of zeolite 4A treated with magnesium hydroxide on the characteristics and gas‐permeation properties of polysulfone‐based mixed‐matrix membranes

Nowadays, new methods for gas‐separation processes are being quickly developed. The separation of CH₄/CO₂ and CH₄/H₂ is usually the subject of most related research studies, especially in the membrane gas‐separation process, because of their important role in industry. In this study, we attempted to improve the separation properties of a polysulfone/zeolite 4A mixed‐matrix membrane by modifying the zeolite particle surface. The method included a simple ion‐exchange reaction of magnesium chloride with ammonium hydroxide that yielded the formation and precipitation of magnesium hydroxide whiskers on the surface of the zeolites. The whiskers could omit most of the nonselective voids by interlocking the polymer chains through them and, consequently, improve the permeability, selectivity, and elastic modulus of the membranes. X‐ray diffraction, energy‐dispersive X‐ray spectroscopy, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and dynamic mechanical analysis proved all the changes recorded after the particle and membrane treatments. SEM images showed the petal‐like morphology of the whiskers that formed on the surface of the particles after the reaction against the smooth surface of the untreated zeolite. At a 30 wt % loading of particles in the polymeric matrix, the selectivities for H₂/CH₄ and CO₂/CH₄ increased by 69 and 56%, respectively; in contrast, the H₂ and CO₂ permeabilities decreased by 2.5 and 10%, respectively. The modulus of elasticity for the treated membrane also increased by 14 and 30% compared to those of the pure and untreated membranes, respectively. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44329.     

Surface modification of microcrystalline cellulose (MCC) and its application in LDPE‐based composites

Microcrystalline cellulose (MCC) was modified by grafting onto its surface ferulic acid, methacryloyl chloride and oleoyl chloride. The efficacy of the chemical modification was confirmed by X‐ray photoelectron spectroscopy. In addition, the size distribution of the cellulosic particles was investigated by optical microscopy and laser granulometry and its hydrophobicity was evaluated using a contact angle method. Finally, to investigate the affinity of modified MCC with a nonpolar polymer and to assess its potential as a biobased reinforcing filler, the modified MCC was compounded into low‐density polyethylene. An organic peroxide, dicumyl peroxide, was added at selected formulations to see if it could further enhance mechanical bonding between the polymer and the particulates. The dispersion was assessed by scanning electron microscopy. Mechanical properties were investigated through tensile testing while the melt rheology of the composites was monitored by small angle oscillatory shear rheology. The acylation modification of the MCC improved the dispersion within LDPE and enhanced the mechanical properties of the composites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44348.     

Ultrasonic vibration assisted grinding of hard and brittle linear micro-structured surfaces

In this paper, a novel ultrasonic vibration assisted grinding (UVAG) technique was presented for machining hard and brittle linear micro-structured surfaces. The kinematics of the UVAG for micro-structures was first analyzed by considering both the vibration trace and the topological features on the machined surface. Then, the influences of the ultrasonic vibration parameters and the tilt angle on the ground quality of micro-structured surfaces were investigated. The experimental results indicate that the introduction of ultrasonic vibration is able to improve the surface quality (The roughness SR_a was reduced to 78 nm from 136 nm), especially in guaranteeing the edge sharpness of micro-structures. By increasing the tilt angle, the surface roughness can be further reduced to 56 nm for a 59% improvement in total. By using the preferred UVAG parameters realized by orthogonal experiments, a micro cylinder array with surface roughness of less than 50 nm and edge radius of less than 1 μm was fabricated. The primary and secondary sequence of the grinding parameters obtained by the orthogonal experiments are as follows: feed rate, tilt angle of workpiece, depth of grinding, vibration frequency and amplitude. The spindle speed in the range of 1000 rpm–3000 rpm does not significantly affect the machined micro-structured surface roughness. Finally, more micro-structures including a micro V-groove array and a micro pyramid array were machined on binderless WC as well as SiC ceramic by means of the UVAG technique. The edge radius on the V-grooves and pyramids are both less than 1 μm, indicating the feasibility of UVAG in machining hard and brittle micro-structured surfaces for an improved surface quality.     

Next generation high‐performance carbon fiber thermoplastic composites based on polyaryletherketones

Interest in carbon fiber reinforced composites based on polyaryl ether ketones (PAEKs) continues to grow, and is driven by their increasing use as metal replacement materials in high temperature, high‐performance applications. Though these materials have seen widespread use in oil, gas, aerospace, medical and transportation industries, applications are currently limited by the thermal and mechanical properties of available PAEK polymer chemistries and their carbon fiber composites as well as interfacial bonding with carbon fiber surfaces. This article reviews the state of the art of PAEK polymer chemistries, mechanical properties of their carbon fiber reinforced composites, and interfacial engineering techniques used to improve the fiber‐matrix interfacial bond strength. We also propose a roadmap to develop the next generation of high‐performance long fiber thermoplastic composites based on PAEKs. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44441.     

Interface enhancement between polytetrafluoroethylene and glass fibers modified with a titanate coupler

The use of glass fibers (GFs), molybdenum disulfide (MoS₂), and talc was evaluated to reinforce polytetrafluoroethylene (PTFE) for potential applications in automobile shock absorber pistons. The orthogonal experiment results show that the optimal GF/MoS₂/talc/PTFE weight ratio was 2:3:3:92 for the PTFE composite; this ratio resulted in better mechanical properties, hardness, low linear expansion, and wear rate. Chemical coupling and high‐temperature activation treatment on the surface of GF greatly enhanced the interfacial adhesion between the PTFE matrix and GF, as revealed by atomic force microscopy analysis. This resulted in reductions in the wear rate and linear expansion coefficient by two orders of magnitude compared with that of PTFE. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44668.     

CO oxidation over structured carriers: A comparison of ceramic foams, honeycombs and beads

This work aims an experimental comparison of different packings on the basis of their pressure drop, mass and heat transfer properties. Ceramic foams, beads and a honeycomb monolith were used as carriers in the oxidation of carbon monoxide. The carriers were coated with active Pt/SnO₂. The CO oxidation rate was measured in the regime of external diffusion control at superficial gas velocities between 1 and 10 m/s. The volumetric rate coefficients and the pressure drop of packings with similar geometric surface area decreased in the sequence particles > foams > honeycomb. The magnitude of the temperature gradient along the catalytic bed decreased as going from honeycomb over larger particles to foams and small particles. Foams were superior over particle beds from the viewpoint of combined high mass transfer and low-pressure drop. The main advantage of foams as compared to honeycomb resided in the radial mixing enabling a better heat transfer to the reactor walls.