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Guardrails are systems designed to keep vehicles in certain places, by preventing access in dangerous areas. They can be a source of injuries because their rigid structure, designed to face high level of strength. Depending on their speed and mass, vehicles can load guardrails in various forms. The authors propose the use of adaptive guardrails, involving polymers, which react different by different load levels. The behaviour is studied using modeling and simulation with the FEM; different types of guardrails and external loads displacement and stress are presented, as support to choose the most convenient type of guardrail for each application. Keywords: adaptive guardrails, traffic security, polymers, FEM simulation

Inexpensive plastic covered greenhouse structures of the type used by the horticulture industry for plant production are frequently used. We have developed “selective film” with the following properties: transmit the visible light portion of the solar radiation spectrum, the only portion utilized by plants for photosynthesis; absorb the small amount of ultraviolet radiation in the spectrum and cause some of it to fluoresce into visible light, useful to plants, absorb infrared radiation , which plants cannot use and which cause greenhouse interiors to overheat. Plant growth inside the experimental greenhouses covered with photoselective films were compared with plants grown inside growth chambers covered with clear conventional greenhouse films. The results are summarized in the paper. Keywords : greenhouses, photoselective film, plasticulture, solar radiation

The kinetics of the equilibrium anionic polymerization of some cyclic siloxanes is modelled by using neural networks. Feedforward neural networks with one or two hidden layers have been used to appreciate the rates of disappearance of octamethylcyclotetrasiloxane and aminopropyl disiloxane at different catalyst concentrations (direct modelling). Alternatively, another neural model has been developed to estimate the amount of catalyst, which leads to an imposed final concentration of siloxane (inverse modelling). Experimental data for the polymerization of octamethylcyclotetrasiloxane in the presence of KOH as a catalyst and 1,3-bis(aminopropyl)tetramethyldisiloxane as a functional endblocker were used as training data sets for neural models. Satisfactory agreement between experimental data and network predictions obtained in validation phases proved that the projected models have good generalization capacities and, consequently, they describe well the process. Keywords: neural networks, direct and inverse neural modelling, polysiloxane, cyclic siloxanes, anionic ring opening polymerization

This paper presents a monitoring methodology of the processing temperature for the polymeric composite materials. An experimental stand was realized consisting of a computer with an acquisition card and the LabVIEW software that allows the real time monitoring of the composite materials temperature during the processing through the aid of a new heat sensor LM 335Z. This digital sensor had proved to be more efficient than the classical thermo-couplings. Using the LabVIEW software, a virtual instrument called “Virtual Thermometer” was created. This virtual instrument has the same functions as a real instrument, but with a much more complexity as well as the possibility of real time measuring, save, analysis and presentation of the collected data. Keywords: monitoring, polymeric composites, virtual instrument

In this paper the linear polymers transport through a nanopore is simulated. The major effects of superimposed electric field and the monomers number on the polymer translocation have been proved. The polymer escape time is inversely proportional with the electric field’s intensity and directly proportional with the polymer’s length. Keywords: transport phenomena, Langevin equation, nanometer pore, translocation time

In this paper the calculation methods of the demolding force in case of thin-wall injected plastic parts with linear, curvilinear or combined profile are presented. The magnitude of this force directly influences the constructive solution of the ejector system. Key words: injected part, demolding force, ejector system

There were investigated the performances of some UV stabilizers systems in the surface layer (gel coat) of unsaturated polyesthers. The changes in colour and in gloss were determined using accelerated degradation methods as well as natural ageing. The correlation of results allowed the proposal of a degradation model of the polyestheric surface layer under UV radiations action.

This paper proposes the insertion of correction coefficients for the volumes of natural gas measured with mechanical gas meters. These coefficients are based on the annual average values of the atmospheric pressure and temperature, also taking into account the altitude of the measuring point, as they were experimentally established in the laboratories of the Petrol – Gaze University in Ploiesti. Keywords: mechanical meters, correction coefficients, natural gas

The incorporation of functionalized carbon nanotubes in a polymer matrix is expected to greatly enhance the physical and mechanical properties of the polymer due to inherent superior properties of carbon nanotubes (CNTs): high modulus and strength, high thermal stability and enhanced electrical conductivity. Nanocomposite materials based on epoxy polymer matrix and different types of functionalized carbon nanotubes were synthesized. The effect of CNTs on dynamic mechanical properties by DMA, on curing process by DSC and themostability by TGA and DTG were studied. The system based on diglycidylether of bisphenol A (DGEBA) cured with a polyetheramine (D230) and reinforced with amino-functionalized double-wall carbon nanotubes (DWNT-NH2) showed lower Tg values. SEM images reveal an enhance of dispersion if amino-functionalized CNTs are used. Keywords: epoxy, nanotubes, nanocomposites, thermostability, glass transition temperature

Literature relates the membrane modification as a way to obtain affinity membranes having new mechanical and physical-chemical properties, specific to each application. One of the most used technique for the modification of the membrane characteristics consists of grafting the different reactive functions on polymeric chain: -COOH, NH2, -SO3H, -X, -OH etc. This paper offers an original variant for preparation of modified polysulphone by Friedel-Crafts acylation and the obtaining of brominated polyphenileneoxide. Keywords: polysulphone, polyphenileneoxide, reactive functions, acylation, bromination