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A number of four polymer conditioned fertilizers, with slow release of active compounds, were synthesized and characterized. The new fertilizers have been obtained in solid form, through a crosslinking impregnation method. The influence of pH, temperature and molar ratio between raw materials on the activity index was investigated in order to reach an optimization of the process. The products were investigated using modern techniques, as Fourier transform infrared microscopy, HPLC, 1H-RMN or scanning electron microscopy. Keywords: slow release, fertilizers, polymers, conditioning

Polymer complexation is one of the convenient routes for the development of new polymeric materials. Polymeric complex based on poly(aspartic acid) and poly(ethylene glycol) is an interesting compound due to its attractive properties brought by the both components. Poly(aspartic acid) belongs to the family of synthetic polypeptides and it is a biocompatible and biodegradable water-soluble polymer, and owing in part to the carboxylic groups has some similar chemical properties to that of poly(acrylic acid). Poly(ethylene glycol) is also an interesting nonionic polymer because it is soluble in water and several organic solvents, due to the presence of both hydrophobic and hydrophilic segments. The near-infrared chemical imaging (NIR-CI) method is the fusion between near-infrared spectroscopy and image analysis with the unique capability to provide both qualitative and quantitative data of localized and space-averaged chemical compositions. The NIR-CI technique is successfully used in pharmaceutical applications to reveal the extent of ingredient blending, particle size distribution, the presence of polymorphs, and trace contaminants. In the present study the homogeneity of the polymeric complex based on poly(aspartic acid) and poly(ethylene glycol) it was evaluated, using NIR-CI technique which was also sustained by zeta potential and FT-IR analyses, the methods being employed in order to characterize the compound as future potential biomaterial structure. Keywords: biomaterial, poly(aspartic acid), poly(ethylene glycol), NIR-CI

The structure of dielectric materials is one of the main important parameter, which determines the durability of products. The degradation process runs differently in various types of polyethylene, because the macromolecules present different level of branching, different crystallinity grades, different chemical resistance. The dissimilarities between the resistance on ageing of different sorts of polyethylene are depicted by FTIR analysis, chemiluminescence determinations and the measurement on electrical resistivity. The consequences on the long term service under g-irradiation degradation are discussed. Keywords: polyethylene materials, degradation, FTIR, chemiluminescence, electrical properties

The amphiphilic polymers can form associated structures in aqueous solution by mutual interaction and/or interaction with other components such as surfactants and active colloidal molecules. In this paper, results regarding nanolevel associative behaviour of chitosan based systems with surfactant and paracetamol are presented. The viscosity measurements of the solutions prepared were made with a view to take into consideration viscosity as an associative parameter. The thin films topography obtained by spin-coating was analyzed by Atomic Force Microscopy (AFM). The nanostructured matrices were investigated by Scanning Electronic Microscopy (SEM), X-Ray Diffraction (XRD) and by Fourier Transform InfraRed (FTIR) Spectroscopy. From FTIR and X-Ray investigations it can be concluded that, at nano - level, in the chitosan matrix, crystalline surfactant and paracetamol domains like nanocapsules are localized. By visual analysis of the AFM and SEM images it can be observed that the nanocapsules are orderly structured in horizontal layers and present a vertical gradient, the paracetamol nanocapsules formed having dimensions in the range of 21 – 170 nm. The chitosan-paracetamol nanostructured matrices obtained by the phase inversion method stand as a remarkable candidate to be used to control release of this drug. Keywords: chitosan, paracetamol, cationic surfactant, structural analysis

The paper presents the corotating twin screw extruder optimization, taking into account the quality of final product. Thus it was established the optimum screws configuration, the optimum screw speeds and the optimum flow rates. Keywords: twin screw extruder, quality, flow rate, screw

A new aromatic diamine, namely 2,2-bis(3-amino-4-oxyhexyloxy-phenyl-4’-butoxyazobenzen) hexafluoropropane, containing two azobenzene side groups have been prepared by modification of 2,2-bis(3-amino-4-hydroxyphenyl) –hexafluoropropane with 4-(6-bromohexyloxy)-4’-butoxyazobenzene in the presence of K2CO3/KI. This monomer showed a mesophase in the range of 103-114°C and can be used for obtaining of polymers with special optical properties. Keywords: butoxyaniline, side azobenzene groups, thermal characterization

Knowing that copolymers of acrylonitrile (AN) with acrylic acid (AA) can be used for the molecular imprinting, three AN: AA copolymers were synthesized by radical copolymerization in emulsion without emulsifier. The copolymer and diosgenin were dissolved in dimethylformamide (DMF) in order to obtain casting solutions with various polymer and template concentrations. The influence of the copolymer and template on the rheological behavior of the solutions was studied in order to establish the best parameters for the casting solutions preparation. The polymer solutions were transformed in membranes by phase inversion in water at room temperature (20oC). By casting the polymer solutions on a glass surface and drawing down with a scraper, a 200 mm thickness film resulted. The diosgenin was extracted from the membrane structure with ethanol, methanol or chloroform in an ultrasonic bath. The molecular imprinting was proved by HPLC on liquid (the extracting solvent after the membrane extraction) and solid phases (after dissolution of membrane parts in DMF). Comparing the sorption capacities of the imprinted materials, for two steroids (diosgenin and stigmasterol), the membrane selectivity towards the template was proved. Keywords: imprinted polymer, molecular recognition, solid phase extraction, bioactive substances,phase inversion

The paper presents a comparative study on the structure of some polyvinyl alcohols used in PVC-S technology. The obtained data clearly showed that the degree of hydrolysis can be determined, with the same high precision through chemical method, IR and 13C-NMR spectra. The carbonyl content determined from the IR spectra also correlates with the carbonyl content determined from 13C-NMR spectra. A fast and reliable IR method for checking the degree of hydrolysis as technological support can be provided, the normalized carbonyl content determined from IR spectrum being linearly correlated with the degree of hydrolysis. Keywords: Polyvinyl alcohols, vinyl alcohol-vinyl acetate copolymers, IR spectra, 1H-NMR spectra, 13C-NMR spectra

Hydrogels are networks consisting of crosslinked hydrophilic polymers that absorb and retain water or biological fluids. Poly(vinyl alcohol) (PVA) based hydrogels are non-toxic, non-carcinogenic, easily processed and therefore have been examined for tissue replacements, artificial skin, hemodialysis membrane and oral drug release systems. The research focuses on the synthesis of PVA–acrylamide based hydrogels, using glutaraldehyde, sodium tetraborate and N,N’-methylenebisacrylamide/sodium tetraborate mixture as crosslinking agents. The crosslinking copolymers were characterized by infrared spectroscopy (IR), thermal analysis (TG, DSC), and swelling behaviour in distilled water at 37.5 0C temperature. Keywords: crosslinked copolymers, poly(vinyl alcohol)-acrylamide, glutaraldehyde, sodium tetraborate, N,N’-methylenebisacrylamide

The new materials have physical and mechanical properties that allow their processing by using classical methods, specific for synthetic polymers. In vitro biocompatibility studies were performed on a primary culture of human dermal fibroblasts by the MTT test. The biocompatibility of the materials was tested in vitro by determining cell viability in a culture of human dermal fibroblasts by using the MTT method. The physical and mechanical properties and also the biocompatibility properties of the new materials recommend them to be used in the manufacture of medical devices. Key words: synthetic polymers, natural polymers, blends, polyvinyl chloride, collagen, elastin, biocompatibility, cell viability