Volume 42, Issue 4

Abstract: This paper presents the obtaining of some composite materials using wood waste (wood chips) and polymer. As thermoplastic matrix, a copolyamide polymer having a low melting interval (125-135°C) was used. Composites were obtained using a two-stage technology: a) wood-polymer pellets obtaining by melt mixing the components; b) composites obtaining by moulding the pellets into a heated press. The influence of wood content on composites properties was studied. Morphological details (by optical and electronic microscopy), thermal behaviour (through TGA and DSC analyses), mechanical properties (tensile, bending and impact strength) and behaviour towards water were investigated. It was concluded that, for a wood content higher than 40%, mechanical properties are getting poorer. Still, even the bending strength is decreasing, it remains 2-8 times higher than that of the composites based on polyolefinic matrix and wood chips. Keywords: composite materials, thermoplastic matrix, copolyamide polymer

Abstract: The global and partial solubility parameters and radii of interaction spheres of two copolymers recommended as viscosity improvers for multi-grade mineral oils – INFINEUM SV 260 and KELTAN 4200 – were determined from solubility data and intrinsic viscosities using 13 solvents both by the classical Hansen’s method and an improved one. The obtained results are in good agreement each other and with intrinsic viscosity data. The values of the intrinsic viscosities obtained using the mineral oil SAE 10W as solvent, for which the two copolymers are intended to be used as viscosity improvers, show that it can be considered practically a very good solvent for INFINEUM SV 260 and a good one for KELTAN 4200. Keywords: multi-grade oils, viscosity improvers, global and partial solubility parameters

Abstract: Liquid crystalline thermosets with biphenyl mesogen in the main chain were prepared by the curing reaction of diglycidyl ether of 4,4¢-biphenol (DGEBP) in presence of methylene-di-chloro-diethylaniline (MCDEA) and 2-amine-biphenyl (2-ABP), used as the curing agents. The product obtained by the curing reaction of DGEBP/MCDEA mixture is characterized by a texture of smectic-like structure. The curing reaction of DGEBP/2-ABP mixture led to a nematic-like structure on temperatures placed in the range of l58 - 1630C. The nematic-like texture obtained for the DGEBP/2-ABP mixture is instable at temperatures higher than 170oC. Keywords: epoxy, liquid crystal, curing, mesophase

Abstract: It is known that the white organic films based on powder coatings have a large use, especially in the appliance industry; however, due to their decorative role, the colour is one of the important characteristiscs of the powder coatings. In order to obtain coloured coatings, coloured pigments, both of inorganic and organic types, have to be used to formulate powder coating compositions. They have to be selected to correspond to the end-use of the coated object, and also to be suitable for the production process for powder coatings and to the application process. The paper presents the procedure of realize the database for the ChromaCalc Paint.2. software using the DATACOLOR d200 spectrophotometer, and also the testing of the database. Keywords: organic coating, powder coating, coloured pigments

Abstract: The aliphatic polyamides provide an extremely broad range of available properties for biological and medical purposes. They can be used as support in biocidal systems. The biocidal polymer coatings can contain hydantoin, imidazolidinone, isocyanurate or oxazolidinone derivatives and have considerable potential as disinfectants for general purpose. The FT-IR spectroscopy was chosen as tool in order to determine the possible changes in the structure of poly(e-caprolactam) after thermal treatment. The shifts in the frequency of absorption bands and the changes in their intensities are monitored. Keywords: poly(e-caprolactam), FT IR spectroscopy, temperature influence

Abstract: Synthesis of orto- and para-aminophenols groups grafted on copolymers is described. The method is applied, extended and optimised for gel-type styrene-divinylbenzene copolymers (S-DVB) with „5” and „7” degree of crosslinking. Keywords: orto- and para-aminophenols groups, styrene-divinylbenzene copolymers

Abstract: Conformational parameters of some heterocyclic polymers containing phenyl-substituted quinoxaline units, phthalimide, 3,4,5,6-tetrachlorophthalimide or phenoxy groups, have been calculated by Monte Carlo method. Several physical properties such as solubility, glass transition temperature, initial decomposition temperature and dielectric constant are discussed in relation with the structure of the polymers and rigidity of their chains. The influence of each pendent group on the properties of the polymers was discussed. Keywords: conformational rigidity parameter, heterocyclic polymers, solubility, high thermal stability

Abstract: The paper deals with the flow analysis of plastic material which flows into the mold cavity using simplifying hypotheses imposed to the injection process. On the basis of software especially developed in C++, the length of the penetration of molten plastic front, volumetric flow rate, time variations of the injection pressure and the radius of the molten front, respectively, have been represented for different plastic materials. Keywords: injection, die forging, fill-in phase, flow front, volumetric flow rate, injection pressure

Abstract: Glass transition temperatures were determined by differential scanning calorimetry (DSC) for the polymer mixtures of polystyrene(PS)/polysulfone(PSF) and their chloromethylated derivatives (CMPS/CMPSF). The polymer mixture was prepared by precipitation method from a common solvent. The glass transition temperature values (Tg) for every compound did not depend on its content in the solid mixture. This behavior is attributed to the incompatibility of the polymers at least in the case of the mixtures obtained by co-precipitation method. The introduction of the chloromethylated groups in para-position of benzene ring for polystyrene and in a, b positions of benzene rings of Bisphenol A leads to the increase of Tg with 10% for polystyrene and to decrease of Tg with 10% for polysulfone. The chloromethylated reaction improves the thermal characteristics of polystyrene and polysulfone and mixture of CMPS/CMPSF. Keyword: glass transition temperatures, DSC, polysulfone, polystyrene, chloromethylated polysulfone, chloromethylated polystyrene

Abstract: It was studied the possibility of using as texture agents in the formulation of some epoxy-polyesteric powder dyes of a cellulosic derivative - encoded AT1 and of an acrylic resin - encoded AT2. From the analysis of the influence of the texture agent AT1 and AT2 respectively, on three epoxy-polyesteric powder dyes (pure white powder, graphite grey and signal black, according to RAL Design Classic Card K7, RAL Farben, Germany), it was established that their main characteristics are not influenced by the presence in the composition of the texture agent. In order to realize the requested textured aspect of the coatings realiyed with epoxy-polyesteric powder dyes in which fornulation there were introduced these texture agents, their concentration must be correlated with the ligand content. Keywords: texture agents, coatings, powder dyes

Abstract: The paperwork presents the principal constituent equations used on study of mincing rubber waste without insertion. These equations permit a study of mincing process on analytical ground, without being necessary, in some cases, to conduct experimental research. For verifying these equations, it is presented here an experimental part too, based on which it can be done a verification of constituent equations. Keywords: constituent equations, mincing rubber waste

Abstract: This paper presents the effect of some rosemary and sage extracts on the thermal stabilization of low-density polyethylene (LDPE). IR and UV spectra of these extracts indicates that the major substances are carnosic acid, carnosol and epirosmanol. Chemiluminescence (CL) resulting from the exothermic termination reaction of peroxi radicals was used for the characterization of effectiveness of these extracts for protection of LDPE. Keywords: rosemary, sage, extraction, antioxidant, chemiluminescence

Abstract: This paper describes the kinetic evolution, in solution, of styrene-N-phenylmaleimide alternating copolymerization. The rate of consumption for the echimolecular composition of the two monomers is shown by the empirical equation VP = kp[M]1.17[I]0.4; there were formulated hypothesys to explain those dependences. The copolymers obtained were analysed by IR and GPC; it was proved the structure of the alternant copolymer and the fact that it results high molecular products. Keywords: styrene-N-phenylmaleimide, alternating copolymerization,alternant copolymer

Abstract: The main aim of this paper is to study the thermal stability of some aromatic copolyethers containing a tetramethylenic spacer. The polymers were synthesized using a phase transfer catalysis technique, starting from 1,4’-dichlorobutane and various bisphenols: 4,4’-dihidroxyazobenzene, 4,4’-dihidroxy-diphenyl, bisphenol A and 2,7-dihidroxynaphthalene. It was studied the correlation between structure - thermostability - degradation mechanism. There were used thermodynamic, thermogravimetric methods, derivative thermogravimetry and differential thermal analysis for the evaluation of the kinetic characteristics and for establishing the correlation between activation energies - the conversion rate. The thermal stability is determined by the azo moieties within the main chain. The thermostability of the copolymer is improved by raising the content of the co-monomer with the highest thermostability. The degradation mechanism derives from successive reactions, with a nucleation complex process. Keywords: thermal stability, liquid crystalline copolyether, azobenzene, thermal degradation mechanis

Abstract: A series of bismaleimides with amide or ester linkages were prepared by condensation-dehydrochlorination reaction of 3(4)- a-chlorosuccinimidobenzoic acid chloride with diamine or diols. The monomers were characterized by thermal stability using dynamic thermogravimetric analysis (TEA) and DSC study. Keywords: bismaleimides, amide, thermogravimetric analysis

Abstract: In this study a series of urethane prepolymers based on diisocyanates (diphenylmethane diisocyanate – MDI, toluene diisocyanate – TDI), castor-oil and filler from bronze aluminum and bitumen in methylene chloride as solvent was synthesized for corrosive protection of equipments utilized in nonferrous ore industry. The polymers were tested to work, for a period, after which the materials were analyzed to see how they resisted in corrosive medium. In ore industry, the corrosion of equipment utilized is both an electrochemical and physical (abrasion) process. In the form of a liquid spray coating, the polyurethane elastomer is especially useful for protecting industrial ore equipments, adding years of service to surfaces that would otherwise suffer from wear and corrosion. The polyurethane coatings have been characterized by means of TEM, TGA, 1H-NMR and IR spectroscopy, and stress-strain measurements. The hardness measurements were effected on disc with a standardized apparatus in grade Shore A (oSh A). Keywords: polyurethane elastomer, coating, corrosive protection