Volume 42, Issue 1

Abstract: The resinic acids, the aniline, the p-aminophenol and the formic aldehyde were reacted at different molar ratios in the presence of hydrogen chlorine. There were obtained formic-aldehyde resins with aminic gropups in their chain. These low molecular mass polymers are solid, friable, soluble in most of molar organic solvents, having colors from red brown for the aniline resin to dark colors for the p-aminophenol resin. The chemical structure of these polymers was identified using IR and H-RMN spectroscopy, as well as by elemental analysis. The thermal properties were also investigated. Keywords: resinic acids, p-aminophenol, aniline, phenolic resin

Abstract: In this paper it is analyzed the influence of epoxy and polyesteric resins reactivity on the characteristics of two types of epoxy-polyesteric powder dyes (7024 graphite grey and 9005 signal black, according to the RAL Design Classic K 7 Card, RAL-Farben, Germany) and of two cover films obtained from them. It was observed that, with the increase of acidity index of poly-esteric resins, a decrease of powder dyes gelification time takes place, as well as the decrease of cover films elasticity and gloss, but also the increase of their tickness. The increase of the epoxy equivalent of the epoxidic resin determines an increase of the powder dyes gelification time and the decrease of the cover films thickness obtained from them. Keywords: epoxy and polyesteric resins, esteric resins, acidity index, powder dyes gelification

Abstract: The paper presents, in a general and sugestive manner, some basic knowledge about nomenclature and concepts usually encontered in the field of liquid crystalline materials (both low molecular compounds and polymers). There are briefly presented: definitions, mesophase types, textures and defects and a short description of liquid crystalline polymers. Keywords: liquid crystalline materials, low molecular compounds, polymers

Abstract: This paper presents the main aspects of an experimental study concerning the reactions of a bifunctional photostabilizator of benzophenonic type (2,4-dihydroxy-benzophenone) with monoisocyanate (phenylisocyanate) and two diisocyanates (2,4-toluylen diisocyanate and 4,4’-diphenylmethanediisocyanate). The conditions for the synthesis of urethane compounds and alophanat are presented as well as the existing ways (with a support of IR spectroscopy, UV-VIS spectroscopy, HPLC – reverse phase and thermal analyses) of these compounds from the numerous of possible theoretical structures. The study of these reactions is useful for revealing some aspects on the way of binding of photostabilizators of this type in polyurethanes macromolecules. Keywords: photostabilizators, isocyanates, urethane compounds, alophanat compounds

Abstract: Interpenetrating polymer networks (IPNs) are a special type of polymer blends, constituted by combination of two or more network polymers, synthesized in juxtaposition. The synthesized IPNs were carried out in order to improve the material properties of many widely used polymers. Although several papers on IPNs have already described the use of polyurethane (PU) based compositions, the importance of PU-epoxy IPNs needs special emphasis. This paper is a review with some results regarding PU-epoxy IPNs, pointing out own studies on synthesis and characterization of PU-modified epoxy resin semi-IPNs. Keywords: epoxy resins, networks, vinyl ester resins, unsaturated resins, graft, morphology

Abstract: The paper presents results concerning the synthesis and characterization, as polymer processing aids, plasticizers and/or lubricants, of some diesters of unsymmetrical structure of phtalic anhydride, by taking into account aliphatic alcohols such as C3, C4, C6, C2-6, izo C10 and izo C13, along with complex alcohols of aliphatic-aromatic nature, such as phenoxy-ethanols. Three series of unsymmetrical diesters were performed considering as special alcohols the 2-phenoxyethanol, 2-[(o-sec butyl)phenoxy]ethanol and 2-[(p-nonyl)phenoxy]ethanol, respectively. The variation of the representative plasticizing and/or lubricating properties as a function of both the length of the aliphatic chain introduced by the aliphatic alcohol and the length and position of the alkyl pendant group existent on the aryl ring of the complex alcohol, was studied. Considering these alternatives, it was possible to obtain either plasticizing or lubricating properties as a function of the structural features. Thus, on the basis of the results recorded it was fully proved the valability and the consistency of the polyfunctionality and assimetry principles. Keywords: unsymmetrical phtalic diesters, plasticizers, lubricants, phenoxy-ethanols

Abstract: The Wittig-Horner reaction is the most general method for regiospecific introduction of carbon-carbon double bounds in organic synthesis. Phase transfer catalyzed reactions are often more easily and cheaply carried out than conventional methods. The paper deals with the synthesis of copolymers functionalized with olefin groups by Wittig-Horner type polymer-analogous reactions in phase transfer catalysis. The copolymer bond aldehyde was reacted with phosphonates to obtain olefin groups grafted on macromolecular support. Keywords: polymer-suported Wittig-Horner reagent, phase transfer catalysed, styrene-divinylbenzene copolymers

Abstract: In this study, a series of three different thermoplastic poly(ether-urethane-urea)s were synthesized from hexamethylene diisocyanate (HDI), polypropylene glycol (PPG) as macrodiols and hexamethylene diamine (HMDA) as chain extender. The molecular weights of the macrodiols were in the range 400 - 2000 g/mol. The polymers have been characterized by means of 1H-NMR, IR spectroscopy and other techniques. Tensile testing was performed on dumbbell-shaped specimens cut from thin films at room temperature on a TIRAtest 2161 tensile tester (Germany). The hard segment contents were calculated on the basis of urea content, as described by Flory, which represents the best method of the evaluation of the material residing in the hard phases. Keywords: poly(ether-urethane-urea), macrodiols, hard segment contents (HSC)

Abstract: Segmented poly (ester-urethanes) elastomers based on poly (ethylene diethylene adipate) diols as a soft segment and aromatic diisocyanates in the hard segment were synthesized by a conventional method. The precipitated polyurethane films have been degraded after a limited exposure to reactive agents: 4,4’-methylenebis(phenyl isocyanate) epichlorohydrin and propylene oxide in benzene. The effects on mechanical properties of precipitated polyurethane films were found to be a measure of the degradation due to reactive agents. 4,4’-methylenebis(phenyl isocyanate) and propylene oxide had an increase in the hard segment content which was associated with increased hard domain crystallinity, hardness and improvement in mechanical properties. It is suggested that the superior mechanical performance may be related to interconnecting hard domain texture by cross-linking process. Theis study attempts to correlate the mechanical properties of the precipitated polyurethane films with the nature of the reactive agents. In all cases, the effect of reactive agents was to increase the ultimate tensile strain, except epichlorohydrin. Keywords: poly (ester urethanes) films, reactive agents, mechanical properties

Abstract: The paper presents two plastic materials from epoxidic resins and compounded polymers families which have properties to visualize stress field produced by mechanical loadings. Using these properties two experimental techniques, photoelasticity and cromoplasticity, were developed for mechanical behaviour investigation of engineering structures. To illustrate the potential of these experimental techniques, in the paper are presented results of a combined analysis undertaken on the state stress in the fastening elements of a hidroagregate, loaded both in elastic and elastoplastic field. Keywords: epoxidic resins, compounded polymers, photoelasticity, cromoplasticity

Abstract: In this study there were investigated some mixtures obtained from epoxy resins and polyaminobismaleimides. The preparation, working conditions and their characterization by IR, softening points and thermogravimetric analysis are also given. Keywords: epoxy resin, polyaminobismaleimide, thermal behaviour

Abstract: Thermal stability of low density polyethylene stabilized with different diamine compounds: N-phenyl-1-naphtyl-amine, N-cyclohexyl-N’-phenyl-p-phenylen-diamine, N-(1,3-dimethyl-butyl)-N’-phenyl-p-phenylen-diamine and N, N’-di-(1,4-dimethylpentyl)-p-phenylen-diamine was investigated by chemiluminescence method. Kinetic parameters depicting the progress in thermal degradation at various temperatures, concentrations and irradiation doses were calculated. Energetic considerations on thermal stability induced by diamine presence are commented and antirad effect of this kind of compounds is emphasized. Keywords: low density polyethylene, diamine compounds

Abstract: Based on the evaluation of the position occupied by silicones in biomaterials field in general, and in hydrolytically degradable materials in particular, some original results obtained in this direction are presented. Keywords: biomaterials, silicone, siloxane-organic copolymers, hydrolytic degradability