Volume 43, Issue 1

Abstract: This paper presents the investigation of the catalytic agent influence on the crystallinity degree of polymers (metallocene polyethylene). Differential scanning calorimetry was the method used to determine the crystallinity. It was underlined that the catalyst has a great influence on the crystallinity of metallocene polyethylene. The results are in good agreement with the preceeding ones [4]. Keywords: polymer, metallocene polyethylene, crystallinity, differential scanning calorimetry, baseline method, First Law method

Abstract: In the paper, a stress strain analysis in the area of central ligament of a cruciform glass-epoxy specimen is presented. Investigation was done experimentally, using strain gauges technique, by application of six gauges in the stress concentration area. The validation of a theoretical model (a special type of a finite element), which was created by authors for analysis of the laminate composite structures, was the aim of this study. A good agreement between numerical calculus and experimental results was observed. Keywords: experimental validation, finite element method, epoxy resin, lamina, cruciform specimen, strain gauges technique

Abstract: The transport process of charged polymer, through a nanopore in a biological membrane is studied. An expression for the polymers flow in terms of the free energy and the friction coefficient is obtained. Keywords: polymer translocation, polymer flow, nanometric pores, biological membrane

Abstract: The paper presents the experimental results obtained in processing rubber waste armed with metallic insertions. The experimental results were obtained appliyng a new technology for processing rubber waste reinforced with metallic insertions. The technology presented in this paper, is based on changes of rubber mechanical properties, at temperatures in criogenic domain. Keywords: rubber, waste, processing, cryogenic domain

Abstract: The Wittig reaction is amongst the most popular methods for regiospecific introduction of carbon-carbon double bonds in organic synthesis. The paper deals with the synthesis of copolymers functionalized with olefin groups by Wittig type polymer-analogous reactions in phase transfer catalysis. The copolymer bond aldehyde was reacted with phosphonium salts to give olefin groups grafted on macromolecular support. Keywords: polymer-suported Wittig reagent, phase transfer catalysed, styrene-divinylbenzene copolymers

Abstract: The exposure of ethylene-propylene elastomers to the action of gamma-radiation causes the modification of chemical state of polymer matrix by the formation of oxygenated products. The accumulation of these dipoles modifies the electrical behaviour of materials, the value of resistance more than three times at increasing dose up to 200 kGy. The absorbtion/resorbtion current measurements demonstrates the wrong consequence of the inversion of polarity for applied voltages. Differences between the two sorts of synthetic elastomers (ethylene-propylene copolymer and ethylene-propylene terpolymer) were pointed out. Keywords: synthetic elastomers, EPDM, EPR, electrical properties

Abstract: In this paper the transport process of charged polymer, through a narrow pore in a biological membrane is studied. The translocation time of a single-stranded polymer through a nanopore may be well computed using a physical-chemical model. The general translocation time formula is presented. Keywords: polymer translocation time, nanometric pores, biological membrane

Abstract: A serials of polyaminobismaleimides with different structures, having amide groups, were synthesized by Michael addition of various diamines (4,4-diaminodiphenylether , 1,4-bis(4-aminophenoxy)benzene, 1,2-bis [2- (4-aminophenoxy)ethoxy ethane to bismaleimides. The obtained monomers and polymers were characterized by infrared (IR) and proton nuclear resonance (1H-NMR) spectroscopy. Thermal characterization of polymer was accomplished by differential scanning calorimetru(DSC) and dynamic thermogravimetric analysis(ATG). The relationship between the structure and the properties was studied as well as the reaction conditions for the synthesis of resins . Keywords: bismaleimides, polyaminobismaleimides, synthesis, thermal and electric properties

Abstract: The atactic polypropylene (APP) recovery as hydro insulation membranes and / or bitumen presents two main advantages: the great quantities that can be reprocessed and the elevated usage life of the obtained products, a consequence of lack of the photo and thermal degradation during usage. It is well know that the photo and thermal degradation rapidly diminishes the utilization properties, namely the usage life. The recovery into hydro insulation membranes and / or bitumen is possible if the APP was selected based on thermo – oxidative stability criteria typically for a good incorporation into the melt bitumen at 180 0 C for 4 – 10 hours and for RTFOT or TFOT tests. The RTFOT thermo – oxidative stability criterion, according to which the mass loosing at 163 0C for 80 min. must be smaller than 0, 8 %, is fulfilled only if the APP has a weight molecular mass greater than 8000 and a solid consistency. If these two criteria are not fulfilled the APP can be recovered as hot melt adhesives. Keywords: atactic polypropylene, practical application, hydro insulation membranes and bitumen

Abstract: This paper presents a comparative numerical simulation of an injection moulding process in the case of an acetabular cup, a basic component in a hip prosthesis, made of UHMWPE (GUR 5113, GUR EP 4224, Novatec PP BC4Y 46420) in order to determine the optimal conditions for injection process parameters. The numerical simulation was performed using fusion finite element Moldflow Plastics Insight software especially designed for injection moulding. Keywords: biocompatible materials, hip prosthesis, injection moulding, acetabular cup

Abstract: 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

Abstract: 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

Abstract: 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

Abstract: New aromatic polyimides have been synthesized by polycondensation reaction of 3,3’-dimethyl-4,4’-diaminodiphenylmethane with benzophenontetracarboxylic dianhydride or hexafluoroisopropylidene diphthalic anhydride in N-methylpyrrolidinone as a solvent, followed by chemical imidization in the presence of acetic anhydride and pyridine at 100°C for 4 h. The obtained polyimides presented excellent solubility, high thermal stability and good film forming ability. The degree of polyimides cure has been observed to have a profound influence on the films fluorescence . Keywords: 3,3’-dimethyl-4,4’-diaminodiphenylmethane; polyimides; solubility; cure; fluorescence

Abstract: Polyurethanes (PUs) based on polyester polyol and aromatic diisocyanate are used as passive isolation bearings in buildings applications. In the present study polyesterdiol and 4,4-diphenylmethane diisocyanate (MDI) have been used in polyurethanes, using glycerine, ethylene or diethylene glycols as chain extenders. Effect of varying the concentrations of diisocyanates and structure of chain extenders on PUs have been discussed with reference to mechanical properties. IR and thermal analysis techniques (TGA and DSC) were used for characterization. The results expose that aromatic character of diisocyanates raises the temperature required to achieve the flexibility in the polymer. Based on their mechanical properties, PUs has great potential for applications where excellent wind and earthquake loads resistance, dynamic-to-static stiffness ratio and vertical and lateral load characteristics are required. Keywords: polyurethanes, passive isolation systems, polyester polyol, aromatic diisocyanate

Abstract: The textile coating is an important process giving rise to new materials. The study of polymer emulsion rheological behavior is very important for establishing the optimal conditions for obtaining the best coated products. The mathematical study of the rheological properties for a printing paste has been presented. Some conclusions in connection composition of coating paste versus rheological behavior have been established. Keywords: rheology, polyacrylate, textile coating

Abstract: In this paper the behavior at elevated temperatures (thermal oxidation) of some new copolymers exhibiting photochromic properties has been studied. These copolymers were prepared by chemical grafting of some azoic dyes on the support-polymers chains. The thermal oxidation has been studied by DTA, TG and DTG in the range of 22°C - 500°C for both support-copolymers and grafted photochromic polymers. The experimental data suggest that, upon heating, various oxidation processes occurs which are accompanied by slight increasing of the sample weight (at moderate temperatures), and oxidative decomposition processes accompanied by more or less intense decreasing in sample weight (at higher temperatures, over 300°C). The temperature values corresponding to these transformations seem to be related to both the polymer and grafted substituent structures. Thus, the halogen containing substituents induced a significant increasing in stability, especially in the case of chlorine containing ones. The imide structure of these substituents seems to induce a higher stability as compared to amic one. Keywords: thermal oxidation, photochromic, azoic dyes