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Rheological measurements of 3; 6; 10 and 12% INFINEUM SV 260 solutions in SAE 10W mineral oil show non-Newtonian behaviour in the temperature range 313-370 K and shear rates ranging between 3 and 1312 s-1: they follow the Bingham model at low concentrations, low shear rates and high temperatures and the Herschel-Bulkley model at high concentration, high shear rates and low temperatures. KELTAN 4200 solutions in the same solvent are more viscous than the corresponding ones given by INFINEUM SV 260 and follow the Herschel-Bulkley model onto the whole studied concentration, shear rate and temperature ranges. The slopes of the lines representing the variation of log viscosity with the reciprocal of temperature increase slightly with concentration between 3 and 10% for INFINEUM SV 260 solutions and decreases for 12%. The lowest slope is given by 3% solution, followed by 12%, and the highest one by 10% solution. KELTAN 4200 solutions present an increase of slope when passing from 3 to 6% and a decrease when the concentration exceeds the last value. The lowest slope was obtained for 12% solution, followed by 3%, while 6% solution has the highest value. This might suggest that KELTAN 4200 could be a better viscosity improver for the mineral oil SAE 10W, both at low and high concentrations. Keywords: rheological behaviour of concentrated polymer solutions, viscosity improvers, multi-grade oils

The organic coatings made with powder dyes constitute an alternative solution to liquid dyes, for thez ensure a proper equilibrium between performance, price and work protection. Depending on the utilization field, this kind of organic coatings may be realized with different degrees of shine, from dull to glossy. In practice there are preferred the dull coatings because the surface defects of the cover films (needle shots, craters, scratches) are less visible on this type of surfaces. In this paper it was analyzed the possiblity of using as a splice agent a carboxyfunctional polyester and it was emphasized the influence of this splice agent on some characteristics of the epoxy-polyesteric powder dyes of white signal type and of cover films made with them. Keywords:organic coatings, powder dyes, splice agent, cover films

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

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

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

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

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

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

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

In this paper the numerical simulation of the injection moulding of the total hip prosthesis (acetabular) cup made of UHMWE is carried out in order to determine the optimal conditions for injection process parameter. The numerical simulation was performed using finite element Moldflow Plastic Insight software especially designed for injection molding. Keywords: injection moulding, acetabular cup, hip prosthesis, plastic material, finite element