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Low softening point temperature glassy frit, reinforcing silica, wollastonite and dicumyl peroxide were incorporated into ethylene-propylene-diene (EPDM) rubber matrix in different amounts in order to obtain ceramifiable composites. Kinetics of vulcanization of the mixes was measured. Mechanical properties, micromorphology, thermal properties and combustibility of the vulcanizates were studied as well as compression strength of the ceramic residue obtained after heat treatment. Studies show that optimal amount of glassy frit from the point of view of ceramification effectiveness in dispersed mineral phase is 40% wt. [ABSTRACT FROM AUTHOR]

Ethylene-vinyl acetate (EVA)/sepiolite nanocomposites were prepared by melt blending in a twin screw extruder. The structural, morphological, thermal, flammability and mechanical properties of the EVA/sepiolite nanocomposites were investigated using X-ray diffraction (XRD), Fourier transform infrared (FTIR), field emission scanning electron microscopy (FESEM), thermal analysis, tensile properties and limiting oxygen index (LOI) measurements. X-ray diffraction analysis and FESEM revealed good dispersion of sepiolite in EVA matrix. The tensile strength of EVA/sepiolite increased by 21% and Young's modulus increased by 47% at 5 wt% and 7 wt% sepiolite content, respectively. The thermal stability and fire retardancy of the nanocomposites improved with sepiolite incorporation. [ABSTRACT FROM AUTHOR]

The overall objective of this work was to study the influence of vinyl acetate (VAc) content on the rheological properties and microstructure of polymer gels based on conventional and high-oleic sunflower vegetable oils and ethylene-vinyl acetate copolymer (EVA). The mechanical properties during gel preparation can be in situ monitored through the evolution of torque with processing time by using the mixing rheometry technique. Linear viscoelastic measurements, as well as differential scanning calorimetry (DSC) tests and morphological observations, were performed on the resulting gels. From the experimental results, it can be concluded that VAc content and melt flow index of the EVA copolymer significantly affect the rheological and thermal responses of polymer gels. VAc content, mainly affecting EVA degree of crystallinity, and melt flow index influence the linear viscoelastic behaviour in opposite directions. On the contrary, the extension of the linear viscoelastic regime and gel-like to liquid-like response transition temperatures are mainly dominated by EVA degree of crystallinity, as confirmed through calorimetry tests and microscopy observations. The different fatty acid profile in sunflower oils tested does not exert an important influence on process rheokinetics and rheological behaviour. [ABSTRACT FROM AUTHOR]

In this work, we report the synthesis and characterization of a novel series of first and second generation Fréchet type dendrons bearing amino-nitro substituted azobenzene units and tetra(ethylene glycol) spacers. These compounds were fully characterized by FTIR, 1H and 13C-NMR spectroscopies, and their molecular weights were determined by MALDI-TOF-MS. The thermal properties of the obtained dendrons were studied by TGA and DSC and their optical properties by absorption spectroscopy in solution and cast film. Molecular calculations were performed in order to determine the optimized geometries of these molecules in different environments. Besides, Langmuir and Langmuir Blodgett films were prepared with the first generation dendrons that were shown to be amphiphilic. Finally, some of the dendrons showed a liquid crystalline behaviour, which was studied by light polarized microscopy as a function of the temperature in order to determine the transition temperatures and the structure of the mesophase. [ABSTRACT FROM AUTHOR]

Abstract: Ethylene vinyl acetate (EVA) composites filled with zeolite (25 vol.%) were prepared using an internal mixer followed by compression molding machine. In order to enhance the thermal properties and fire retardancy of the composites, an intumescent flame retardant consisting of ammonium polyphosphate (APP)/pentaerythritol (PER) was incorporated into the composites. Two kinds of flame retardants were used which are untreated APP (APP1) and silane treated APP (APP2), where their effectiveness was evaluated by means of differential scanning calorimetry (DSC) and also thermogravimetric analysis (TGA). The results showed that both types of flame retardants have the ability to enhance the thermal stability of EVA/zeolite composites by producing charred layer which protects the underlying composites from the action of flame. Moreover, the incorporation of APP1 and APP2 has a significant effect on the composites degree of crystallinity. Meanwhile the results of tensile testing showed that the composites with APP2/PER exhibit better tensile properties compared to that with APP1/PER. This is expected since the application of silane-treated APP (APP2) could improve the dispersion of APP particles within EVA matrix. [Copyright &y& Elsevier]

The present work shows the behavior of non-treated and chemical pre-treated peach palm fibers, as reinforcement polymer composites. Chemical treatments with H2O2, NaOH, and C3H3N and their effects on adhesion performance of the fiber with unsaturated polyester resin are carried out. SEM is used to determine a time exposition of the fibers to chemical reagent and thermal characterization of these fibers after set time is performed. A hand lay-up method is applied to develop the composites and they are tested for tensile strength and Izod impact strength. The TGA of the fibers pre-treated with H2O2 20V for 144 h show better thermal stability when compared with non-treated fiber. Other treatments do not improve their thermal properties. [ABSTRACT FROM AUTHOR]

In this paper, a new kind of biodegradable aliphatic polyetheresteramide copolymers (PEEA) based on $$\varepsilon$$ -caprolactone, 6-aminocaproic acid, and poly(ethylene glycol) (PEG) were synthesized by melt polymerization method. The obtained copolymers were characterized by 1H-NMR. The thermal properties of PEEA copolymers were studied by DSC and TGA/DTA under nitrogen atmosphere. The water absorption and hydrolytic degradation behavior was also studied in detail. With the increase in PEG content or the decrease in caprolactone content, the water absorption of the copolymers increased accordingly. For the hydrolytic degradation behavior, with the increase in PEG content or caprolactone content, the degradation rate increased then. [ABSTRACT FROM AUTHOR]

Abstract: The effect of irradiation on tensile, dynamic mechanical properties, thermal properties and morphology of ENR-50, EVA and ENR-50/EVA blend was investigated. All the samples were irradiated using a 3.0MeV electron beam (EB) machine with doses ranging from 20 to 100kGy. Results indicate that the gel fraction of ENR-50, EVA and ENR-50/EVA blend increases with irradiation dose. Concerning tensile properties, it can be seen that EB radiation increases the tensile strength of all the samples, increases the elongation at break of ENR-50 and ENR-50/EVA blend, reduces the elongation at break of EVA, increases M200 (modulus at 200% strain) of ENR-50 and EVA, while decreases M200 of the ENR-50/EVA blend. For dynamic mechanical studies, it was found that EB radiation increases the T g of all the samples due to the effect of irradiation-induced crosslinking. The compatibility of ENR-50/EVA blend also found to be improving upon irradiation. In the case of thermal properties, it was detected that T m, T c and the degree of crystallinity of ENR-50/EVA blend increase with an increase in irradiation dose. This was due to the perfection in the crystal growth occurring upon radiation. Morphology changes play a major role in the changes of the properties of ENR-50/EVA blend. Finally, it can be concluded that ENR-50/EVA blend can be vulcanized by EB radiation. [Copyright &y& Elsevier]

Two standard vinylidene chloride copolymers, the first containing approximately 9 mass% methyl acrylate and the second containing vinyl chloride at a nominal 15 mass% were prepared by radical suspension techniques using a series of peroxide and azo initiators (all of approximately the same half-life temperature for decomposition). The nature of the initiator could impact the stability of the resulting polymer in two ways. Instability could be introduced either via end-group effects or by attack of residual initiator fragments on the finished polymer during isolation and residual monomer stripping. In this case, the relative thermal stability of the resins produced was assessed by exposing samples to heat and shear in an air environment in a two-roll mill (Brabender Prep-Mill). The rate and extent of degradation was most readily apparent from color development during this treatment. The more thermally stable polymers were produced using initiator radicals that did not attack the polymer during isolation/stripping processes. [ABSTRACT FROM AUTHOR]

An imidazolium-based zwitterion containing two oxyethylene units was obtained as a colorless liquid at room temperature. The equimolar mixture of the liquid zwitterion and lithium bis(trifluoromethylsulfonyl)amide showed an ionic conductivity of over 10−4S cm−1at 80 °C, which was higher than those of mixtures composed of analogous solid zwitterions. [ABSTRACT FROM AUTHOR]

The article reports on the findings a study which examined the reaction of 3-(4-bromophenylimino)-5-phenyl-2,3-dihydrofuran-2-one (I) with malononitrile (IIa) and ethyl cyanoacetate. The study, which was performed under financial support by the Russian Foundation for Basic Research, revealed that the reaction of I with IIa in the presence of triethylamine on heating provide 5E)-2-amino-1-(4-bromophenyl)-4-oxo-5-(2-oxo-2-phenylethylidene)- 4,5-dihydro-1H-pyrrole-3-carbonitrile (IIIa).