Browse Articles

The paper presents the synthesis and characterisation of a new Mannich polyether polyol with high nitrogen content and thermostable isocyanuric structure. The synthesis was performed by the alkoxylation in the absence of any catalyst of a Mannich base obtained by the reaction of cyanuric acid with a Mannich precursor reagent 1,3-oxazolidine. The Mannich polyol was characterised by 1H NMR and 13C NMR, infrared spectroscopy and by the determination of some usual characteristics such as hydroxyl number, viscosity, amine echivalent, water content. The main application of this polyol is the production of “spray” rigid polyurethane foams with higher thermostability and inherent flame retardancy properties. Keyword: 1,3-oxazolidine; isocyanuric Mannich polyether polyol; rigid polyurethanic foams

Analysing the Maddock and Egan dispersive zones, their thermal homogeneisation effect and their role in dispersing agglomerated particles within the melt, resulted a correlation between the barrier zone slit height, h3 and the length of the barrier zone, L02 assuring the dispersing of the agglomerated particles within the melt. Given the role the Maddock and Egan zones have, based on the obtained relations, their dimensions (h3, B3, L02,j) can be calculated. Keywords: Maddock and Egan, thermal homogeneisation, in dispersing, barrier zone

The effect of organofunctional silane coupling agents on the morpho-structural (XRD) and thermal (TGA) characteristics of the organically modified montmorillonite was examined. The modification of the organosilicates was carried out using organofunctional silane coupling agents in ethanol. The obtained results demonstrate the interaction of the silane-coupling agents with the organosilicate layers. The thermal stability and the basal spacing of the organosilicates increases with silane coupling agent’s concentrations. Using organosilicate modified with functionalized coupling agent PP based nanocomposites with enhanced thermal stability and a more disordered lamellar structure were obtained. Keywords: organically modified montmorillonite, silane coupling agents, polymer nanocomposites

This paper describes the kinetic evolution, in solution, of N-phenylmaleimide - vinyl acetate alternating copolymerization. The rate of consumption for the equimolar composition of the two monomers is described by the empirical equation: Valt=k . [M]1.70[I]0,49. There were formulated hypotheses to explain those dependences. The copolymers obtained were analysed by SEC. It was proved the structure of the alternate copolymer and the fact that high molecular products results . Keywords: N-phenylmaleimide, vinyl acetate, alternate copolymerization, alternate copolymer

Thermoplastics are widely used for engineering application and customer goods. One of the application area is automotive industry. The passengers’ compartment is an example of using high quality materials and advanced design solution in order to achieve aesthetic interiors and performance when safety is the issue. The impact of the passenger’s head with the cockpit module is studied by experimental and numerical simulation. Material models are studied in order to obtain good results and to validate the numerical model for further investigation. Keywords: thermoplastics, material characterization, impact, experiment, numerical simulation

In this paper, a methodology to evaluate the dynamic fracture toughness of polymethyl methacrylate (PMMA) is presented. The proposed methodology is based on a hybrid-numerical formulation and requires the evaluation of the dynamic stress intensity factor along the experimentally measured dynamic crack fronts, and the three-parameter Weibull stress model for brittle fracture. The apparent fracture toughness master curves are determined for Double Cantilever Beam (DCB) specimens of PMMA with different thickness. Keywords: dynamic fracture toughness, polymethyl methacrylate, Weibull master curve

The paper presents two methods for similarity measurement of plastic textured images, and also for identification and localization of defective region in textured images. In order to have less sensitive statistic features regarding to rotated image, we introduce the notion of average co-occurrence matrix. With the purpose of algorithm validation, the images are divided into four equivalent regions. For the proper region similarity measurement, a decision theoretic method is used. In the fractal approach, we consider a new fractal dimension derived from box-counting algorithm, named effective fractal dimension, with an increasing efficiency for texture classification. Two experimental studies, one for statistical features and one for fractal type features, in a plastic simulated wood case, validate the algorithms. The algorithms are implemented in Visual C++ and Matlab. They allow the simultaneously display of both the investigated region, and the Euclidian distance between this and a reference image. The results confirm the fact that the distances between the regions without defect are relatively small, and the distance between a region with defect and a region without defect is relatively large. Also, the results show that features extracted from average co-occurrence matrix and the effective fractal dimension have a good discriminating power. Keywords: texture similarity, statistic features, fractal dimension, plastic simulated wood, defect detection

This paper presents the effects of high energy irradiation on polyvinylchloride samples, some of them containing filler (1 and 5 % mica). The generation of dipoles as oxygenated radiolysis products modifies electrical behavior of polymer matrix. The presence of mica influences the rate of oxidation by decreasing the progress in the accumulation of oxygenated products. The values of volume resistivity, dielectric constant and loss factors are consequently changed as the mica content differs due to the adsorbent action of filler. Keywords: PVC, mica, irradiation, volume resitivity, dielectric constant, loss factors

The three new polyanionic polymer conjugates were synthesized by the chemical bonding of some N-mustard derivatives of di-(b-chloroethyl)-amine and tri-(b-chloroethyl)-amine with poly(maleic anhydride-alt-vinyl acetate). The chemical structure of the compounds obtained was verified by FTIR, H1-NMR and elemental analysis. Keywords: poly(maleic anhydride-alt-vinyl acetate) conjugates, alkylating agents

The paper investigates the influence of rubber elastic properties on modal behaviour of truck tyres. Hyperelastic models and numerical values of coefficients in these models used for defining rubber hyperelastic behaviour are presented. The choice of the appropriate hyperelastic model to be introduced in the tyre finite element model is motivated. The main characteristics of the finite element model of a radial truck tyre are presented. A series of modal analyses is performed, in which elastic properties of tread rubber are modified in a wide range. Finally, the influence of tread rubber elasticity characteristic values on natural frequencies and mode shapes of truck tyres is analysed. Keywords: tyre, hyperelasticity, modal behaviour, finite element model