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The more reliable values of the crystallization temperature were obtained from the non – isothermal DSC thermograms recorded at low cooling rate. The crystallization time was evaluated from the isothermal DSC thermogrames recorded at those temperatures at which the crystallization occurs. PP nucleated with Irgastab NA 21, has crystalline phase that contains the smallest spherulites, as compared to those nucleated with Irgastab NA 04 and Irgaclear DM. The incorporation of the nucleating / clarifying agents into the polymer matrix is homogeneous only if the melt processing conditions were well defined for each of them. A dependence on the molecular weight of the nucleated PP morphology was observed. The spherulite size decreases with the increase of the molecular weight. Keywords: crystalization, nucleation, polypropylene, nucleating agent, spherulite

This article presents the experimental results regarding the glucose influence on poly (vinyl alcohol) (PVA) films. The results of infrared spectroscopy (FTIR), atomic force microscopy (AFM) and X-ray diffraction (XRD) measurements revealed the surface and structural changes induced by increasing the glucose concentration. Keywords: PVA, AFM, XRD, FTIR

In this paper the 3D simulation model of typical porous polymer is presented. Porosity growth was caused by numerical handling of a spatial pores network. Although the algorithm has a good accuracy it is noticed that the final average pore sizes for simulated polymer networks are larger than the desired pore size. Keywords: polymer network, porosity, tissue engineering

Mixing and processing characteristics, mechanical properties and thermal characteristics of dimethyl vinyl silicone/poly(tetrafluoroethylene)(MVQ/PTFE) blends were investigated. With the rise Poly(tetrafluoroethylene) (PTFE) portion in blends, the values of both torque and total torque of blend materials decrease. In MVQ/PTFE blends, PTFE act as inactive filler and some mechanical properties decreases in blends compared to component polymers with the increases portion of plastic in blend compositions. The heterogenity of MVQ/PTFE blends was determined by thermomechanical analysis-dilatometry. Silicone (MVQ) and PTFE show separate Tgs, which indicate that they are not compatible. Thermogravimetric analysis of these blends, show that with increased portion of PTFE in blends, the TGA characteristics Tbeg and T5% is moved at higher temperature, which mean increased of thermal blend stability. Keywords: blends, dilatometry, TGA

This paper is focused on the main static and dynamic characteristics in case of rubber elements designated to damp the vibrations transmitted to the surrounding buildings by means of the railway. Thus, the experimental methods performed on a stand having harmonic excitation in case of actual loading under dynamic regime both stationary and transient attaining the resonance point are presented. Based on this, the system dynamic parameters such as: dynamic rigidity, critical damping fraction, dissipation coefficient (hysteresis) can be determined. Aiming this the free damped vibration method and the controlled excitation method with monotone increasing variation for the excitation frequency have been used. In this way can comparatively be determined both the rigidity and the damping dynamic characteristics of the rubber for various manufacturing receipts taking into account the chemical composition as well as the manufacturing process. Finally, the paper presents experimental results obtained by our research institute ICECON Bucharest in cooperation with University “Dunãrea de Jos” of Galaþi during the works carried out for the tram rails in Bucharest, Romania. Keywords: elastomer, rigidity, damping, vibration, structural noise, antivibrating insulation

Using the linearity of the term we will deduce a new formula for the calculus of the fracture strength for composites with randomly dispersed fibres. This formula will depend on the reinforcement volume fraction. Using the mean values for longitudinal and/or transversal modulus, with respect to the rotated reference system, we will obtain an original relation for the calculation of the elasticity modulus for composite plates with a randomly dispersed reinforcement. We preferred to write this relation in a similar manner to the one used for the failure strength, using the linearity related to . Experimental determinations were made for three sets of samples obtained from composite plates with various mass fractions of reinforcement, confirming thus the theoretical results obtained by the authors. Keywords: composite materials, fracture strength, longitudinal/transverse modulus

One major disadvantage of polymeric composites is their low electrical conductivity. This is a trail-and-error study regarding PMC’s conductivity modification by filling the polymer matrix with various powders. Clay, CNT and Ferrites were used as fillers, Epoxy Epiphen RE 4020 with Epiphen DE 4020 as hardener was used as matrix and simple type fabric of alternate kevlar and carbon untwisted tows was used as reinforcement. The mechanical properties of a PMC are improved by using reinforcements so it is naturally to ask what is happening when a reinforced composite is formed with filled polymer matrix. Plate samples were formed and their electrical conductivity was evaluated. The filler’s concentration was considered and information was used in order to form the reinforced composite with the highest conductivity. Keywords: CNT, Ferrite, Clay, Epoxy, Fiber Fabric Reinforcement

Cellulose composites with maleic anhydride – dicyclopentadiene copolymer matrix were obtained by “in situ” free-radical polymerization. The syntheses were carried out in two different solvents: toluene and dioxane, aiming at determining their influence upon both the polymerization process and properties of the resulting materials. The composite materials obtained were characterized both structurally by FT-IR, XRD and SEM, and from the thermal behavior point of view by TGA-DSC-MS analyses. Keywords: cellulose composites, maleic anhydride – dicyclopentadiene copolymer, in situ polymerization

Among the methods used nowadays for studying the microscopic properties of polymers, proteins, membranes and other bio-materials is the molecular dynamics. One of the widely used software in molecular dynamics is Gromacs developed at the University of Groningen. From a computational perspective, molecular dynamics requires large computational power and an increased storage capacity. Different physical models were recently defined for trying to reduce the complexity and to make more efficient the computational it molecular models. In this paper we present the Gromacs implementation of a new multiscaling MD model with a space dependent multiscaling parameter and we discuss efficiency measurements. Keywords: polymers, molecular dynamics, Gromacs, multiscaling modeling

A rheological study was performed in order to appreciate the compatibility of the expanded polystyrene beads with the concrete matrix. In order to prepare homogeneous dispersions of the expanded polystyrene (EPS) in the cement paste, the EPS beads were first surface pre-treated with carboxymethylcellulose (CMC), intending to achieve the compatibility between the hydrophilic concrete matrix and the hydrophobic polystyrene beads. In this study, the mass fractions of aggregates, cement and water were maintained constantly for all the probes and it was checked the influence of two parameters: the EPS mass fraction and the CMC concentration. The study was performed with EPS mass fractions between 0.0028 – 0.0041 and with CMC – water solutions having concentrations between 0.5% - 2% (mass). The results showed that CMC can achieve the compatibility between concrete and EPS and that within a 2% CMC solution an important amount of EPS beads can be incorporated. Keywords: lightweight concrete, expanded polystyrene, concrete rheology