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Waxes are critical to hot melt adhesives performance in terms of thermal stability and mechanical properties. The thermal behavior of EVA with microcrystalline and polyethylene waxes have been investigated by infrared spectroscopy and physical-mechanical testing. Infrared spectroscopy was used to follow the ratio evolution of band intensities E730/E720 with type and content of EVA –wax blends. The tensile properties have been measured at two EVA/wax ratios: initially and after exposure at 175 and 200oC. A significant correlation was found among tensile strength at break / elongation and type and ratio of EVA / wax ratio. Semiquantitative spectral information and evolution of physical – mechanical properties have been used to improve the behavior of EVA hot melt adhesives at work temperature. Keywords: wax, elastomers EVA, thermodegradation, cristallinity

Powders of poly (vinyl alcohol) with different degrees of polymerisation and hydrolysis have been reacted with phosphorous acid in homogeneous conditions. The influence of experimental conditions on the substitution degree has been investigated. Analytical, spectral, viscosimetric and thermogravimetric methods were used to analyse the influence of tacticity, crystallinity and degree of polymerisation and hydrolysis of parent poly (vinyl alcohol) on the properties of the phosphorilated products. Keywords: phosphorilated poly (vinyl alcohol), degree of hydrolysis, degree of polymerisation, tacticity

Epoxy resins with mezogenic groups were prepared from diglycidyl ether of 4,4`-bisphenol (DGEBP), as rigid block, and 4,4’-diaminodiphenyl sulphone (DDS), as curing agent. A nematic-like structure was developed in time, in the temperature range of the curing process between 151 and 2530C. The mesophase formation was proved using optical microscopy (OM) and wide-angle-X-ray scattering (WAXS) techniques. Keywords: epoxy, mesophase, liquid crystal, curing, network

The paper deals with the synthesis and characterisation as plasticizers and/or lubricants of some unsymmetrical diesters of sebacic acid by using superior branched aliphatic alcohols, such as 2-ethyl-hexanol, isodecanol and isotridecanol, along with complex aliphatic-aromatic alcohols, like 2-phenoxyethanol, 2-[(o-sec-butyl)phenoxy]ethanol and 2-[(p-nonyl)phenoxy]ethanol, respectively. Valuable plasticizing and/or lubricating properties were recorded, as a function of the polar / unpolar ratio within each structure of the considered product. A semnificative improved thermal resistance was also observed. In this way, the valability and consistency of the theoretical premises admitted, like the asymmetry and polyfunctionality principles, were fully proved. Keywords: unsymmetrical sebacic diesters, plasticizers, lubricants, phenoxy-ethanols

It was studied the influence of urheomelamineformaldehydic resin adds, as flow modifier, on the main characteristics of some epoxi-polyesteric powder dye of white signal type and of cover films made with these. It was established that the introducing in the forming of the uhreomelaminoformaldehydic resin ensures the decrease of the gelification time, the disappearence of needle shots and of craters appearing in the cover film made with the standard dye and the reducing of the orange skin aspect intensity. In order to ensure these positive influences it is necessary to introduce in the forming relatively high ratios (9.1%) of urheomelamino-formaldehydic resin. By also introducing an acrylic flow modifier, the positive influences may be obtained with smaller ratios (~ 3.2%) of urheomelaminoformaldehydic resin. Keywords: adds, main, forming, needle shots, forming

The 2,6-di-tert-butylphenol (DtBP) can be oxidated with O2, in the presence of some catalysts based on M(II) complexes with Schiff bases, in DMF. The metal complexes contain Mn and tetradentate Schiff bases derived from salen, as ligands. The transformation degree, the nature and contents of the products obtained were followed by 1H RMN spectroscopy and gas chromatography. Kinetic data indicate that the reaction is of the pseudo-first-order, as compared with dioxygen consumed. Keywords: kinetics, oxidation, Mn(II) Schiff bases complexes

New aromatic aldehydes were prepared in the conventional literature manner by Williamson etherification reaction of p-chlorobenzaldehyde with p-substituted phenols, or by esterification reaction of cyanoacetic acid with p-hydroxybenzaldehyde in the presence of dicyclohexylcarbodiimide (DCC). The obtained monomers have been confirmed structurally by IR, 1H-NMR spectroscopy, elemental analysis and characterized by solubility, thermal behavior and refraction index. Keywords: monomer, aromatic aldehyde, mesogenic precursor

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

The main route of obtaining bismaleimides is the reaction between maleic anhydride and primary diamines. First stade occured with forming maleamic acid, then cyclicised to bismaleimide in presence of the acetic anhydride, sodium acetate or other dehydration agents. In the reaction mixture there appeared secondary products as bisisomaleimide, bisacetamide and unreacted bismaleamic acid. A study of their presence and influence on the polyaminobismaleimide resin processability and properties using DSC, ATG and IR methods was performed. Keywords:bismaleimides, secondary products, polyaminobismaleimide

This paper proposes a genuine mathematical pattern for the study of the unsteady phenomena that characterize the working out of natural gas polyethilene pipeline networks. The calculation programme elaborated on the basis of the mathematical model allows the determination of the period of the two steady regimes between which the unsteady movement takes place, for each pipeline of the network. Keywords: pipeline, natural gas, network, unsteady movement