Showing papers by "Cornelia Vasile published in 2012"
TL;DR: In this paper, an unbleached and bleached Kraft cellulose pulp fibers modified with a long chain carboxylic acid in cold plasma conditions have been used as reinforcements in low density polyethylene (LDPE).
Abstract: Unbleached and bleached Kraft cellulose pulp fibers modified with a long chain carboxylic acid, i.e. oleic acid in cold plasma conditions have been used as reinforcements in low density polyethylene (LDPE). The purpose of the modification is to enhance the interfacial adhesion between cellulose and matrix and to increase the dispersability. Composites containing up to 10 wt.% of untreated and modified cellulose pulp fibers with LDPE were prepared by melt mixing. The samples were characterized by processing behavior, mechanical and rheological properties, SEM, contact angle measurements, TGA and DSC. It was found that when the modified pulp fibers were incorporated into composites matrix, most of the properties have been improved.
73 citations
TL;DR: In this paper, physically cross-linked cryogels containing polyvinyl alcohol (PVA) and various amounts of microcrystalline cellulose were obtained by freezing/thawing technique.
69 citations
TL;DR: In this article, the authors used solid-state CP/MAS 13 C nuclear magnetic resonance, Fourier transform infrared spectroscopy and X-ray diffraction for the characterization of acetylated kraft pulp.
48 citations
TL;DR: In this article, a commercial fluid catalytic cracking catalyst and Red Mud were used as a catalyst for the co-pyrolysis of scrap tire with oily wastes from ships, scrap tires and their blends.
43 citations
TL;DR: Because the release of drugs from drug-intercalated montmorillonite was controllable, these new materials have a great potential as a delivery host in the pharmaceutical field.
42 citations
01 Jan 2012
TL;DR: In this article, the preparation of polyvinyl alcohol (PVA)/chitosan (CS) blends with different compositions was studied by means of polarized light optical microscopy, FT-IR spectroscopy, DSC, DMTA, TG/DTG and rheological measurements.
Abstract: The present study deals with the preparation of polyvinyl alcohol (PVA)/chitosan (CS) blends with different compositions. The physico-chemical characterization and compatibility have been studied by means of polarized light optical microscopy, FT-IR spectroscopy, DSC, DMTA, TG/DTG and rheological measurements. The film-forming ability of the blends was confirmed by rheological tests, as they showed higher viscosity and improved viscoelastic properties in comparison with pure PVA. The obtained films were transparent and homogenous with enhanced mechanical properties and thermal stability.
33 citations
TL;DR: It has been established that an increase of CS content in hydrogels composition leads to a higher swelling ratio for all formulations and to a decreased released amount of nitric oxide donor compound.
29 citations
TL;DR: In this article, a ternary copolymer/clay nanocomposite containing 3.5% sodium montmorillonite (Na+-MMT) via seeded emulsion polymerization was obtained.
24 citations
01 Jan 2012
TL;DR: In this paper, the chemical composition, structural features and surface active properties of alkali lignin, separated from the hydrolyzate of the birch wood sawdust treatment in a moderately alkaline water solution at a temperature below 100 °C, were studied.
Abstract: The chemical composition, structural features and surface active properties of alkali lignin, separated from the hydrolyzate of the birch wood sawdust treatment in a moderately alkaline water solution at a temperature below 100 °C, were studied. The separated lignin was rich in p-oxyphenylpropane fragments and carbonyl groups, but contained a relatively low amount of aliphatic hydroxyl and methoxyl groups. The carboxyl groups were weaker than those in kraft lignins. The lignin aqueous solutions were structured, containing both nano- and micro-sized colloidal particles. The pronounced amphiphilic character of the lignin molecules governed their low critical micelle concentration (CMC) values and enhanced the surface activity at the water-air and liquid-liquid interfaces. When decreasing the pH and increasing ionic strength, the surface activity of lignin at the air-water interface grew, while that at the oil-water interface dropped. Scanning electron microscopy (SEM) images revealed that the microstructure of the lignin surface consisted of globules, forming extended clusters of the “grape-bunches” type.
15 citations
TL;DR: A ligand was prepared by condensation of the salicylaldehyde with 2-aminopyridine obtaining 2-(salicylidene) aminopyrididine (SB) with a high capacity for complexing Cu(II) ions as mentioned in this paper.
Abstract: Schiff bases and their complex combinations with metallic ions represent a class of compounds with antimicrobial activity. A ligand was prepared by condensation of the salicylaldehyde with 2-aminopyridine obtaining 2-(salicylidene) aminopyridine (SB) with a high capacity for complexing Cu(II) ions. The new compound has been characterized by physical constants (melting point, solubility, stability) and the chemical structure was confirmed by elemental, spectral (IR, UV–visible, 1H NMR and 13C-NMR) and thermal analyses. The elemental analysis gives a coordination ratio of 1:2 metal:Schiff base. Lethal dose 50 (DL50) values of new Schiff base and their complex with metallic ions were established. The antimicrobial activity of this complex was tested in comparison with the activity of the corresponding Schiff base on strains of Staphylococcus aureus, Bacillus cereus, Bacillus subtilis, Escherichia coli, Candida albicans, and Klebsiella. These were compared with the activity of the reference drugs (chloramphenicol, tetracycline, ofloxacin and nystatin) on the above-mentioned strains. It has been established that all compounds tested were very active against both Gram-positive and Gram-negative bacteria. Copyright © 2012 John Wiley & Sons, Ltd.
14 citations
TL;DR: In this paper, a semi-synthetic hydrogel based on poly(N-isopropyl acrylamide-co-diethylene glycol diacrylate) inserted onto a collagen porous membrane was presented.
Abstract: The preparation of a semi-synthetic hydrogel based on poly(N-isopropyl acrylamide-co-diethylene glycol diacrylate) inserted onto a collagen porous membrane, it was previous presented. The synthesis of the hydrogels was performed through radical copolymerization of N-isopropyl acrylamide (NIPAM) with diethylene glycol diacrylate (DEGDA) also as crosslinking agent, using ammonium persulfate as initiator and N,N,N′,N′-tetramethylethylene diamine activator, and it was achieved in the presence of the collagen matrix. In this paper the thus prepared hydrogels are characterized by Differential Scanning Calorimetry, Scanning Electron Microscopy and for their swelling capacities. A kinetic model was studied to investigate the swelling mechanism of the semi-interpenetrated polymeric network. The swelling behavior was found dependent on the hydrogel composition and to the external stimuli such as temperature and pH of environment. This manner of acting recommends these materials as smart materials with potential applications in tissue engineering and pharmaceutical field as for example bioproducts carrier matrices.
TL;DR: In this paper, a two-step grafting procedure was applied to cellulose/chitin (CC) mix fibers, namely activation under the action of cold plasma discharges, followed by reaction with N-isopropylacrylamide (NIPAAm) and poly(N-iso-polycyclic acrylamides) (PNIPAm) to obtain fibers with responsiveness to external stimuli.
Abstract: A two-step grafting procedure was applied to cellulose/chitin (CC) mix fibers, namely: activation under the action of cold plasma discharges, followed by reaction with N-isopropylacrylamide (NIPAAm) and poly(N-isopropylacrylamide) (PNIPAAm) to obtain fibers with responsiveness to external stimuli. The graft samples were characterized using attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction, scanning electron microscopy coupled with energy-dispersive X-ray microanalysis and antimicrobial testing. All obtained results confirm the morphological and structural changes after plasma treatment which determine the modification of cellulose fiber properties. It was estimated from XPS data that the degrees of modification/grafting were about 23% for CC/NIPAAm and 13% for CC/PNIPAAm. Such treatment could be transferred to practical technologies, particularly in textile applications and special applications in the medical field. Copyright © 2012 Society of Chemical Industry
TL;DR: In vitro and in vivo release of the theophylline, loaded in mixed polysaccharidic cellulose/chondroitin sulfate (C/CS) hydrogels has been evaluated and a good in vitro-in vivo correlation was found.
TL;DR: In this article, the effect of amount and type of compatibilizing agents is evaluated using electronic microscopy and dielectric spectroscopy, to obtain the optimum materials structure.
Abstract: The article emphasizes the improvement of compatibility in a polymer blend composed of two normally incompatible constituents as LDPE and PA6. The effect of amount and type of compatibilizing agents is evaluated using electronic microscopy and dielectric spectroscopy, to obtain the optimum materials structure.
11 Mar 2012
TL;DR: In vivo 30 days testing performed by subcutaneous implantation showed that the X/CS matrices were easilyabsorbed without side-effects, demonstrating their biocompatibility and effectiveness as potential drug delivery systems.
Abstract: The in vitro and in vivo biocompatibility of xanthan/chondroitin sulfate hydrogels (X/CS) in differentmixing ratios was investigated. The in vitro biocompatibility evaluation was performed by a chemiluminescent assayusing microorganisms such as Saccharomyces pombe. The cellular growth of S. pombe in presence of thexanthan/chondroitin sulfate hydrogels containing up to 20 % chondroitin sulfate was examinated comparatively withxanthan hydrogel.The in vivo evaluation was performed by toxicity test and subcutaneously implantation in rats. It has been establisheda lethal dose (LD50) bigger than 3200 mg/kg for all studied hydrogels, therefore they are nontoxic materials.The in vivo 30 days testing performed by subcutaneous implantation showed that the X/CS matrices were easilyabsorbed without side-effects, demonstrating their biocompatibility and effectiveness as potential drug delivery systems.