Rheological and morphological characteristics of multicomponent polysulfone/poly(vinyl alcohol) systems

A series of blends obtained from polysulfone (PSF) or chloromethylated polysulfone (CMPSF) and poly(vinyl alcohol) (PVA) in N‐methyl‐2‐pyrrolidone were investigated by means of attenuated total reflection Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), rheology and atomic force microscopy (AFM). Mechanisms through which specific interactions developed via hydrogen bonding in ternary systems affect the blend properties were established from FTIR spectra. The results confirm the presence of hydrogen bonding in PSF/PVA and CMPSF/PVA blends at 0.5 and 0.75 weight fractions of PVA, respectively. Consequently, the type of interactions and structural peculiarity of polymers in the blends as well as the composition of polymer mixtures modify the rheological functions, evidencing the orientation or mobility of chain segments in the shear field. The results derived from rheological measurements are consistent with those above, evidencing significant changes for blends with a greater amount of PVA (i.e. 50/50 and 25/75 (w/w) PSF/PVA and CMPSF/PVA blends, respectively). These blends represent the optimum compositions and possess specific properties, confirmed by the glass transition temperatures. Additionally, the specific microarchitecture of the blends, determined using AFM, represents excellent scaffolds as porous membranes for biomedical applications. © 2014 Society of Chemical Industry     

Contribution of Chain Ends and Chain Stiffness on the Solution Properties of Polysulfone

This paper is concerned with the conformational characteristics of polysulfone in dilute solutions of N,N-dimethylformamide, as evidenced by viscometric data, in order to use these results in more complicated structures with different properties and applications. The dependencies of the solution properties on the molecular weight oligomers and in higher molecular weight regions were quantitatively explained, by considering the effects of chain ends and chain stiffness, according to Yamakawa theory.     

Microstructure,Surface Characterization,and Electrochemical Behavior of New Ti-Zr-Ta-Ag Alloy in Simulated Human Electrolyte

Metallurgical and Materials Transactions A - A new Ti-20Zr-5Ta-2Ag alloy was elaborated and characterized regarding its microstructure, its native passive film composition and thickness, its...     

Surface characterization and biocompatibility of titanium alloys implanted with nitrogen by Hardion+ technology

In this study, the new Hardion+ micro-implanter technology was used to modify surface properties of biomedical pure titanium (CP-Ti) and Ti?C6Al?C4V ELI alloy by implantation of nitrogen ions. This process is based on the use of an electron cyclotron resonance ion source to produce a multienergetic ion beam from multicharged ions. After implantation, surface analysis methods revealed the formation of titanium nitride (TiN) on the substrate surfaces. An increase in superficial hardness and a significant reduction of friction coefficient were observed for both materials when compared to non-implanted samples. Better corrosion resistance and a significant decrease in ion release rates were observed for N-implanted biomaterials due to the formation of the protective TiN layer on their surfaces. In vitro tests performed on human fetal osteoblasts indicated that the cytocompatibility of N-implanted CP-Ti and Ti?C6Al?C4V alloy was enhanced in comparison to that of the corresponding non treated samples. Consequently, Hardion+ implantation technique can provide titanium alloys with better qualities in terms of corrosion resistance, cell proliferation, adhesion and viability.     

Corrosion susceptibility of implant materials Ti-5Al-4V and Ti-6Al-4Fe in artificial extra-cellular fluids

The paper is aimed at detecting the corrosion susceptibility (generated by the potential gradients, due to the pH changes) of implant materials Ti-5Al-4V and Ti-6Al-4Fe alloys exposed in extra-cellular fluids for long term (10 000 exposure hours) in comparison with pure titanium. The titanium and its ternary alloys exhibited spontaneous passivity in Ringer’s solutions of pH=6.98, 4.35 and 2.5, simulating the real situations that can arise in surgical applications. Potential gradients determined in presumptive extreme pH conditions indicate that there is no probability for local corrosion. Impedance spectra were fitted with one time constant equivalent circuit, typically for protective, compact oxide film. The fitting parameters indicate long-term stability of the passive layers in surgical implant conditions. Atomic force microscopy (AFM) and spectral infrared (IR) data are important arguments in supporting the conclusion that titanium and its ternary alloys have a very good corrosion resistance in long-term functional conditions.     

Cationic hybrids from poly(N,N‐dimethylaminoethyl methacrylate) covalently crosslinked with chloroalkyl silicone derivatives effective in binding anionic dyes

The synthesis and characterization of some novel ionic organic/inorganic hybrids containing quaternary ammonium salt groups in the side chain, built on the basis of poly(N,N‐dimethylaminoethyl methacrylate), as an organic component and cation provider, and chloroalkyl‐functionalized silicone derivatives as crosslinkers and anion generators, are reported in this work. The resulted structures were investigated using Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and energy dispersive X‐ray spectroscopy. The swelling behavior of the ionic hybrids in water as a function of pH as well as the water vapor sorption capacity in dynamic regime was also studied. The cationic hybrids have a higher swelling capacity at pH 2 compared with deionized water (pH 6) due to the presence of tertiary amine groups belonging to the organic compound. The ionic organic/inorganic hybrids were tested as potential sorbents for anionic species such as dyes [e.g., methyl orange (MO)]. The equilibrium sorption capacity increased with the increase of the organic component up to around 32 mg MO/g hybrid. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43942.     

Physico-Chemical Characterisation of Lipids from <Emphasis Type="Italic">Mytilus galloprovincialis</Emphasis> (L.) and <Emphasis Type="Italic">Rapana venosa</Emphasis> and their Healing Properties on Skin Burns

Black Sea molluscs and gastropods are the most studied organisms from the Romanian littoral zone. In particular, those from the Mytilidae species are of great interest because biochemical investigations have shown that they can be sources of biological active substances which can have different applications (e.g. food additives). We report here the extraction of lipids from two different species of molluscs (Mytilus galloprovincialis L., Mediterranean mussel) and gastropods (Rapana venosa, hard-shell clam). The extracts were evaluated in terms of antioxidant and composition properties and their healing properties were tested on skin burns in Wistar rats. Our studies proved that the two lipid extracts contained a relatively complex distribution of compounds, in terms of characteristic indices, polyunsaturated fatty acids (PUFA) and vitamins E and D. The presence of such compounds rendered the extracts very efficient in healing induced skin burns in Wistar rats. The histological analysis showed a reduction in the time of healing (12-13 and 13-15 days for the Mytilus galloprovincialis (L.) Rapana venosa extracts, respectively) compared to 20-22 for untreated animals, based on results from tissues and blood samples. Our investigations have been proved to be promising in terms of future potential applications of the extracts as skin-care products, cosmetics and/or pharmaceutical preparations owing to their dermorestitutive properties.     

Design,Characterization, and Antibacterial Performance of MAPLE-Deposited Coatings of Magnesium Phosphate-Containing Silver Nanoparticles in Biocompatible Concentrations

Bone disorders and traumas represent a common type of healthcare emergency affecting men and women worldwide. Since most of these diseases imply surgery, frequently complicated by exogenous or endogenous infections, there is an acute need for improving their therapeutic approaches, particularly in clinical conditions requiring orthopedic implants. Various biomaterials have been investigated in the last decades for their potential to increase bone regeneration and prevent orthopedic infections. The present study aimed to develop a series of MAPLE-deposited coatings composed of magnesium phosphate (Mg₃(PO₄)₂) and silver nanoparticles (AgNPs) designed to ensure osteoblast proliferation and anti-infective properties simultaneously. Mg₃(PO₄)₂ and AgNPs were obtained through the cooling bath reaction and chemical reduction, respectively, and then characterized through X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and Selected Area Electron Diffraction (SAED). Subsequently, the obtained coatings were evaluated by Infrared Microscopy (IRM), Fourier-Transform Infrared Spectroscopy (FT-IR), and Scanning Electron Microscopy (SEM). Their biological properties show that the proposed composite coatings exhibit well-balanced biocompatibility and antibacterial activity, promoting osteoblasts viability and proliferation and inhibiting the adherence and growth of Staphylococcus aureus and Pseudomonas aeruginosa, two of the most important agents of orthopedic implant-associated infections.     

N-methylimidazolium functionalized strongly basic anion exchanger: Synthesis,chemical and thermal stability

The synthesis and characterization of gel and porous strong base anion exchangers with N-methylimidazolium functional groups and the evaluation of their chemical stability in aggressive media and thermal behavior are reported. Strong base exchange capacity values, FT-IR spectroscopy as well as ESEM images proved the content of ionic groups and the morphology structure of the anion exchange resins.Both synthesized resins presented a very good chemical stability in hydrogen peroxide compared to the commercial strong base anion exchange resin, Amberlite IRA-400. It was also shown that the porous strong base anion exchange resin exhibited a better stability in aggressive media of high concentration than gel-type resin. The thermal stability of the samples was evaluated by dynamic thermogravimetric analysis in nitrogen gas. Comparing the TG and DTG curves it can be found that the degradation curves of the samples are close to each other in shape under the heating rate conditions. The differences for the samples between in the different heating rate are the typical temperatures and the residue rate of the decomposition.     

Influence of deposition technique on the protective properties of epoxy films

The electrochemical impedance spectra, the anodic polarization curves and the time dependence of paint capacitance and paint resistance have been used in this paper to evaluate the protective properties of epoxy films on carbon steel substrate. The coatings were formed using four deposition techniques (brushing, immersion, cathodic and anodic electrodeposition) with the aim to determine the effect of deposition type on the anticorrosive performances of epoxy paint. Interpretation of Nyquist and Bode impedance spectra with the immitance analysis Equivcrt. programme has established an electrical equivalent circuit with two time constants fitted to describe the electrodeposited epoxy/carbon steel system in the 3 % sodium chloride solution and an electrical equivalent circuit with four time constants fitted in case of epoxy films applied by brush or immersion. The anodic polarisation measurements show nobler corrosion potentials and smaller dissolution current densities for the carbon steel in the presence of the electrodeposited films in comparison with epoxy coatings applied by brush or with the immersion technique. The values of the porosity, water uptake, and ionic transport through the film emphasize the higher performances of the electrodeposited films, characterized by uniformity, porosity absence, low water permeability and few conductive pathways.