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The effect of an organophosphoric insecticide on the thermooxidative degradation of the diglycidil ether-bisphenol A epoxy resin was investigated, using infrared spectroscopy, thermogravimetric and thermodifferential analysis, pyrolysis-gas chromatography and elemental analysis. The results indicated that studied organophosphoric insecticide exercises an influence upon the degradative process of uncured resin by catalysing its decomposition in the lower temperature region. At the same time, the tested insecticide promotes the formation of a phosphorus containing thermostable solid residue. Keyword: epoxy resin, organophosphoric additive, thermooxidative degradation

An experimental study of local heat transfer at the melting of single spherical particles into a flowing liquid is presented in this paper. Local heat transfer coefficient at the particle surface, and local Nusselt number were determined using the photographical technique. Ice-spherical particles having 0,045 m in diameter, and distillated water were used in experiments. The investigations were carried out at the temperature of 303 K at 1 atm pressure, and at several values of water flow velocity ranging from 0,0971 to 0,2279 m/s. The results outline the influence of Reynolds number and proces duration on local Nusselt number. Keywords: heat transfer, local heat transfer coefficient, liquid – solid heat transfer

A series of polydimethylsiloxane-polyethyleneoxide graft copolymers, obtained by hydrosilylation reactions of unsaturated polyethyleneoxides with polysiloxane copolymers containing Si-H groups have been analyzed and characterized from their tensioactive properties point of view and by determination of HLB values. The ratio between the values of siloxane and alkyleneoxide component influences the values of superficial tension (20-37 mN/mm) and of HLB (3-18). HLB values indicate different type of applications of the polymers in various fields. Keywords: silicone surfactants, HLB (Hydrophilic Lipophilic Balance), hydrosilylation, graft copolymers

This paper presents two different procedures for the configuration optimization of a glass fibre reinforced laminate in order to enlarge the load capacity of different structures where these materials could be embedded. By some experimental tests, the authors have established the optimal forming pressure of laminate belonging to a glass fibre fabric reinforced composite. A second experimental aspect taken into account was the determination of the optimal number of laminate, in both situations being attended the obtainment of the highest values for ultimate strengths. The Finite Element Method gives the possibility of a constructive optimization of the composite, the parameters taken into consideration depending on the followed purpose. Keywords: epoxy resin, lamina, finite element method, forming pressure, interlaminar strength

The paper investigates the effect of organic phase on yield and inherent viscosity in liquid-vapor interfacial polycondensation and the effect of reaction temperature and reagents molar-ratio on yield, inherent viscosity and molecular weight in liquid-liquid interfacial polycondensation of cyclohexylphosphonic dichloride (CPD) with bisphenol A (BA). A comparative study between liquid-liquid and vapor-liquid interfacial polycondensation of CPD with BA was performed. Keywords: polyphosphonate, interfacial polycondensation, bisphenol A, cyclohexylphosphonic dichloride

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