A study on the use of phenoxy resins as compatibilizers of polyamide 6 (PA6) and polybutylene terephthalate (PBT)

In this study we investigated the potential of phenoxy resins as compatibilizers in the blending of two high‐volume engineering thermoplastics—polyamide 6 (PA6) and polybutylene terephthalate (PBT), in an effort to establish the usefulness of blending as a method of recycling of mixed plastic wastes. It was found that phenoxy resins formed miscible blends with PBT, formed grafted copolymers with PBT through ester exchange reactions, and—though formed immiscible blends with PA6—produced energetic interactions in the form of hydrogen bonding with PA6. The ternary blend systems of 70 parts PA6, 30 parts PBT, and respectively 5, 10, and 30 parts phenoxy resins, all by weight, revealed at two‐phase nature—PA6 as the continuous phase and miscible blends of PBT and phenoxy resins as the dispersed phase—and were found to be stable to phase coarsening by annealing with mechanical properties at least as good as those of the component polymers.     

Chemical modification of vegetable oils for lubricant applications

Owing to the unfavorable impact on the environment of mineral oil-based lubricants, there has been a steady increase in the demand for biodegradable, environment-friendly lubricants. However, development of a biodegradable base fluid that could replace or partially substitute conventional mineral oil is a big challenge. Vegetable oils are recognized as rapidly biodegradable and are thus promising candidates as base fluids in environment-friendly lubricants. Vegetble oils have excellent lubricity, but poor oxidation and low-temeprature stability. This paper presents a series of structural modifications of vegetable oils using anhydrides of different chain lengths. The reaction was monitored and products were confirmed by NMR, FTIR, gel permeation chromatography, and thermogravimetric analysis (TGA). Experimental conditions were optimized for research quantity and for laboratory scale-up (up to 4 lb=1.8 kg). The thermo-oxidation stability of these new lubricant base fluids was tested using pressure differential scanning calorimetry and TGA. The chemically modified base fluids exhibit superior oxidation stability in comparison with unmodified vegetable oils. These base fluids in combination with suitable additives exhibit equivalent oxidation stability compared with mineral oil-based formulations.     

Accuracy and longitudinal reproducibility of quantitative femorotibial cartilage measures derived from automated U-Net-based segmentation of two different MRI contrasts: data from the osteoarthritis initiative healthy reference cohort

Magnetic Resonance Materials in Physics, Biology and Medicine - To evaluate the agreement, accuracy, and longitudinal reproducibility of quantitative cartilage morphometry from 2D U-Net-based...     

Equilibrium and kinetics study of methyl violet adsorption by pineapple leaf fibers-cl-poly(acrylic acid-co-2-dimethyl amino ethyl acrylate) hydrogel

The pine apple leaf fiber-cl-poly(acrylic acid-co-2-dimethyl amino ethyl acrylate) hydrogel is prepared by crosslinked graft copolymerization of acrylic acid and 2-(dimethyl amino) ethyl acrylate onto the pine apple leaf fibers to be used as an adsorbent for the remove dye from aqueous solutions. Several characterization techniques like Fourier transform infrared spectroscopy field emission scanning electron microscopy-Energy-dispersive X-ray spectroscopy and X-ray diffraction analysis. The synthesized hydrogel shows strong water swelling characteristics (780.93%) and also exhibits faster deswelling property. The methyl violet (MV) adsorption data are fitted well with the Freundlich isotherm model with maximum monolayer adsorption capacities 625 mg/g for MV. The equilibrium kinetics follow pseudo second order model together with intra particle diffusion, one step process. Thermodynamic parameters show that the MV adsorption by the hydrogel is spontaneous and endothermic in nature. The overall removal efficiency is found to be 98.23% under optimum condition.     

Poly(vinyl alcohol) composite films with high percent elongation prepared from amylose‐fatty ammonium salt inclusion complexes

Amylose inclusion complexes prepared from cationic fatty ammonium salts and jet‐cooked high amylose starch were combined with poly(vinyl alcohol) (PVOH) to form glycerol‐plasticized films. For the octadecylammonium salt complexes, elongation was significantly higher than the PVOH control when the amount of complex incorporated was from 20% to 70%. For the dodecyl‐ and hexadecylammonium salt complexes, elongation was significantly higher than PVOH films for 20% to 40% incorporation of cationic complex. Tensile strength declined with increasing levels of amylose‐ammonium salt complex, and surface hydrophobicity (contact angle) was significantly higher than PVOH films. Microscopy showed no phase separation or phase inversion, suggesting intimate mixing due to ionic interactions between cationic ammonium salt complexes and the hydroxyl groups of PVOH. The high elongations of these films and increased water contact angles are marketable advantages, along with the lower cost and increased biodegradability of the starch‐based component. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44110.     

Correlation of viscosity ratio,morphology, and mechanical properties of polyamide 12/natural rubber blends via reactive compatibilization

Natural rubber (NR)-modified polyamide 12 (Nylon12/NR) was produced by melt blending Nylon12 and NR in the presence of polystyrene/maleated natural rubber (PS/MNR) copolymer as a reactive compatibilizer. The influence of compatibilizer loading on viscosity ratio, morphology, and mechanical properties of the blends was investigated. As a consequence of the reactive blend between Nylon12 and maleated NR in PS/MNR, the formation of amide and succinimide linkages was set at rubber-Nylon12 interfaces. Thus the dispersion of rubber particles was improved, and the particle coalescence was prevented so that the fine morphology with good interfacial adhesion was stabilized. This also resulted to enhance the blend viscosity and to lower viscosity ratio. The data revealed strong correlation between low viscosity ratio and fine spherical morphology of the compatibilized blends. An optimum PS/MNR compatibilizer content was at 7 phr to produce good dispersion of small rubber domains (size ≤0.3 μm) in Nylon12 matrix. Thermal properties by DSC revealed that crystallization temperature of Nylon12 was lowered by the presence of NR and crystallinity of Nylon12 was slightly affected by the PS/MNR content. An enhancement of mechanical properties, especially the impact energy was observed without suffering the tensile and flexural properties. Compared to the neat Nylon12, the compatibilized blends showed an increase in impact energy by a factor of 5. This large enhancement is successfully interpreted in term of the toughening effect by rubber phase of suitable dispersed size and the interparticle distance.     

Hydromagnetic flow past a rotating porous plate in a conducting fluid rotating about a noncoincident parallel axis

Summary The hydromagnetic flow of an incompressible viscous electrically conducting fluid past a porous plate is investigated when the plate rotates with a uniform angular velocity about an axis normal to the plate and the fluid at infinity rotates with the same angular velocity about a non-coincident parallel axis. It is shown that in the presence of a uniform magnetic field parallel to the axis of rotation the boundary layer thickness decreases with an increase in either the suction at the plate or the magnetic parameter M. In the presence of suction at the plate, the velocity component u in the direction normal to the plane containing the axis of rotation of the plate and that of the fluid increases with an increase in M, while the velocity component v in the transverse direction parallel to the plane of the plate decreases with an increase in M. For a fixed value of M, at a given location u increases with an increase in the suction parameter S while v decreases with increasing S. For a fixed value of M, at a given location both u and v decrease with an increase in the blowing parameter S₁. Further, for a fixed value of S₁, at a given position u increases with an increase in M but v decreases with increasing M. It is shown that no torque is exerted by the fluid on the plate, and non-coaxial rotations of the plate and the fluid at infinity have no influence on the torque.The solution of the heat transfer equation reveals that for given values of the suction parameter S, Prandtl number P and Eckert number E, the temperature at a given point in the flow increases with increasing M. On the other hand, for fixed values of M, P and E, the temperature at a given point decreases with increasing S. No steady distribution of temperature exists when there is blowing at the plate.     

Remarkable Vapochromic Behavior of Pure Organic Octahedron Embedded in Porous Frameworks

Vapochromic behavior is employed to selectively monitor the vapor changes in surrounding environment, particularly for toxic gas leaking and floating detection. Thus, sensitive trapping and accurate response to different toxic vapors are critical factors in vapochromic sensing. In this work, a self‐assembled hybrid that consists of fluorescent organic octahedron encapsulated by metal–organic polyhedron (MOP) is reported. The fluorescent octahedron is used as a responsive sensor to probe various solvent vapors, while the MOP is employed as a protector to prevent the corrosion of solvents to the organic octahedron. The hybrid exhibits remarkable vapochromic behavior to different solvents, and shows the highest selectivity and sensitivity specifically to acetone. In addition, acetone vapor under different conditions is utilized for further studying the response mechanism of the hybrid. This work presents a promising vapochromic sensor with good stability, selectivity, and sensitivity. The study is expected to open up the applicability of MOP‐based hybrids for specific molecular capture, interim storage, controlled release, and advanced sensing.     

Metal Immiscibility Route to Synthesis of Ultrathin Carbides,Borides, and Nitrides

Ultrathin ceramic coatings are of high interest as protective coatings from aviation to biomedical applications. Here, a generic approach of making scalable ultrathin transition metal‐carbide/boride/nitride using immiscibility of two metals is demonstrated. Ultrathin tantalum carbide, nitride, and boride are grown using chemical vapor deposition by heating a tantalum‐copper bilayer with corresponding precursor (C₂H₂, B powder, and NH₃). The ultrathin crystals are found on the copper surface (opposite of the metal–metal junction). A detailed microscopy analysis followed by density functional theory based calculation demonstrates the migration mechanism, where Ta atoms prefer to stay in clusters in the Cu matrix. These ultrathin materials have good interface attachment with Cu, improving the scratch resistance and oxidation resistance of Cu. This metal–metal immiscibility system can be extended to other metals to synthesize metal carbide, boride, and nitride coatings.     

A Hypoxia‐Responsive Albumin‐Based Nanosystem for Deep Tumor Penetration and Excellent Therapeutic Efficacy

Uncontrolled cancer cell proliferation, insufficient blood flow, and inadequate endogenous oxygen lead to hypoxia in tumor tissues. Herein, a unique type of hypoxia‐responsive human serum albumin (HSA)‐based nanosystem (HCHOA) is reported, prepared by cross‐linking the hypoxia‐sensitive azobenzene group between photosensitizer chlorin e6 (Ce6)‐conjugated HSA (HC) and oxaliplatin prodrug‐conjugated HSA (HO). The HCHOA nanosystem is stable under normal oxygen partial pressure with a size of 100–150 nm. When exposed to the hypoxic tumor microenvironment, the nanosystem can quickly dissociate into ultrasmall HC and HO therapeutic nanoparticles with a diameter smaller than 10 nm, significantly enabling their enhanced intratumoral penetration. After the dissociation, the quenched fluorescence of Ce6 in the produced HC nanoparticles can be recovered for bioimaging. At the same time, the production of singlet oxygen is increased because of the enhancement in the photoactivity of the photosensitizer. On account of these improvements, combined photodynamic therapy and chemotherapy is realized to display superior antitumor efficacy in vivo. Based on this simple strategy, it is possible to achieve the dissociation of hypoxic‐responsive nanosystem to enhance the tumor penetration and therapeutic effect.