Nanofibrous nonwovens based on dendritic‐linear‐dendritic poly(ethylene glycol) hybrids

Dendritic‐linear‐dendritic (DLD) hybrids are highly functional materials combining the properties of linear and dendritic polymers. Attempts to electrospin DLD polymers composed of hyperbranched dendritic blocks of 2,2‐bis(hydroxymethyl) propionic acid on a linear poly(ethylene glycol) core proved unsuccessful. Nevertheless, when these DLD hybrids were blended with an array of different biodegradable polymers as entanglement enhancers, nanofibrous nonwovens were successfully prepared by electrospinning. The pseudogeneration degree of the DLDs, the nature of the co‐electrospun polymer and the solvent systems used for the preparation of the electrospinning solutions exerted a significant effect on the diameter and morphology of the electrospun fibers. It is worth‐noting that aqueous solutions of the DLD polymers and only 1% (w/v) poly(ethylene oxide) resulted in the production of smoother and thinner nanofibers. Such dendritic nanofibrous scaffolds can be promising materials for biomedical applications due to their biocompatibility, biodegradability, multifunctionality, and advanced structural architecture. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45949.     

Multiscale Observation of the Fatigue‐Induced Damage Mechanisms in Carbon‐Black Filled Styrene‐Butadiene Rubber

Filled rubber materials exhibit a complex macroresponse characterized by stress softening, hysteresis, and dissipative heating when they are cyclically loaded. The relationship of these inelastic features to the microstructure changes is far from being fully established. This paper deals with the damage mechanisms in sulfur‐vulcanized styrene‐butadiene rubber (SBR) specimens in the diablo form reinforced with carbon‐black (CB) and zinc‐oxide (ZnO) fillers, and submitted to tension cyclic loading at room temperature. The microstructure alteration is characterized at different relevant scales and at different zones of the diabolo specimen by means of various technologies in the aim to report valuable insights about the mechanisms responsible for the macroresponse of this rubber‐filler material system. IR absorption spectra reveal that increasing filler content induces more interfacial interaction between CB and SBR chains. The environmental scanning electron microscopy (ESEM) observations show relevant altered morphologies of elastomeric chains with a predominant effect of both CB and ZnO fillers. A mesoscale observation of material density variation is presented using X‐ray computed tomography and the results are compared with those issued from ESEM.     

Hybrid 2D nanofibers based on poly(ethylene oxide)/polystyrene matrix and poly(ferrocenylphosphinoboranes) as functional agents

Template smart inorganic polymers within an organic polymeric matrix to form hybrid nanostructured materials are a unique approach to induce novel multifunctionality. In particular, the fabrication of one-dimensional materials via electrospinning is an advanced tool, which has gained success in fulfilling the purpose to fabricate two-dimensional nanostructured materials. We have explored the formation of novel hybrid nanofibers by co-spinning of poly(ferrocenylphosphinoboranes) Fe A [{Fe(C₅H₅)(C₅H₄CH₂PHBH₂)} _n] and Fe B [{Fe(C₅H₅)(C₅H₄PHBH₂)} _n] with poly(ethylene oxide) (PEO) and polystyrene (PS). Fe A and Fe B contain main-group elements and a ferrocene moiety as pendent group and have different properties compared to their only carbon-containing counterparts. The use of PEO and polystyrene provided a matrix to spin those inorganic polymers as hybrid nanofibers which were collected in the form of a nonwoven mat. They were characterized by multinuclear NMR spectroscopy, scanning electron microscopy (SEM), and IR spectroscopy. Thermal properties of the polymers have been checked by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). ¹H, ³¹P, and ¹¹B NMR and IR spectroscopy revealed the nature and types of interactions of the components after co-spinning. The SEM micrographs identify the underlying unidirectional morphology of the generated hybrid nanofibers. Nonetheless, the DSC and TGA confirmed the significant boost toward the thermal stability of the resultant multifunctional fibers. It is believed that these unique types of multifunctional electrospun nanofibers will open new avenues toward the next generation of miniaturized devices.     

Application of integrated computational chemistry system to the design of inorganic membranes

Today inorganic membranes attract a lot of interest as a growing field. Main focus of those activities is on the development of membrane materials, which can offer high permselectivities with acceptable high permeances. The need for high permselectivity beyond those limited by Knudsen flow requires the estimation of the factors, which determine the permselectivity. Plausible theoretical models based on physical or chemical reasoning is desirable to guide systematic development efforts for designing next generation inorganic membranes. Here we reviewed our attempts to generate theoretical models based on the molecular dynamics method for this purpose. As a first attempt, simulation was performed at specific conditions where the Knudsen theory can be applied and can be reproduced well by our simulation methodology. Molecular dynamics simulation at 373 K of the permeation of iso- and n-butanes through ZSM-5 type silicalite membrane are presented. After 200 ps of simulation time the permeation of n-butane was observed whereas the permeation of iso-butane was not observed. The calculated permeability of n-butane, which is close to experimental data, is also presented. A study on the affinity membrane for the separation of CO₂ at high temperature is presented and the prospect of permselectivity of CO₂ is demonstrated.     

Experimental Study of the Salt Effect in Vapor/Liquid Equilibria Using Headspace Gas Chromatography

The salt effect on vapor/liquid equilibrium for an ethanol/water system was studied at 70 °C using the Headspace Gas Chromatography technique. The azeotropic point of the system was eliminated in the presence of the salts studied. All the salts investigated in this work exhibited a salting out effect which followed the order of NH₄Cl > NaCl > CaCl₂ and which increased with increasing salt concentration. Good agreement with Furter's equation was observed for the experimental data with unsaturated NaCl salt. The salt effect parameter, determined from Furter's equation, was found to be a function of the liquid concentration.     

Effect of Gamma Rays on Corn Grains. Part III. Effect of Post-Irradiation Storage on Some Technological Properties of Corn Grains and Fatty Acids

The effect of storage after irradiation of corn grains on steeping process, starch isolation, quality of by-products and fatty acids composition of germ oil was investigated. It was found that post-irradiation storage led to a decrease in water absorption and protein solubilization during steeping process. The starch yield was lower, contained a high percentage of protein and was darker from above 500 Krads. Post-irradiation caused a change in the proportions and disappearance or induced new fatty acids in the corn germ oil.