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Experimental thermal properties on carbon nanotube with polymer matrix composites are analyzed. Increasing of thermal conductivity with carbon nanotube percentages enhancing is obtained and some phenomenological considerations on the heat transfer mechanisms are presented. Keywords: carbon nanotubes, thermal conductivity, effusivity

The paper presents the experimental results obtained for the Necuron 1020 rigid polyurethane specimens with stress concentrators, at traction test. The resistances of these specimens are evaluated based on the critical distances theory, obtaining a good agreement with the experimental results. Keywords: rigid polyurethane, the critical distances theory

Physical properties, such as thermal and dielectric characteristics, of some aromatic polyimides which contain methylene units have been investigated. The results indicated that the polymers were highly thermostable with decomposition temperature over 450°C and low dielectric constants. The thermogravimetrical values processed by differential method Freeman-Caroll showed that the activation energies and reaction orders are lower in air than in nitrogen. Keywords: methylene units, polyimides, thermal characterization, activation energy, dielectric constants

Modulus I interlaminar fracture toughness of wood laminated composite materials has been evaluated using the critical strain energy release rate associated with the onset of crack growth in double cantilever beam specimens (DCB). The advantage of using the DCB test for determining the critical strain energy release rate in the case of wood laminated composites relies on the working method which is focused on failure analysis in adhesive layer through the presence of initial interlaminar crack, but also due to the energetic approach in deduction of calculus relations. Data analysis was conducted by two methods namely, the corrected compliance method which is based on the linear elastic fracture mechanics principles, and the area method which accounts the whole shape of load-displacement curve obtained through a complete loading-unloading cycle. In general there is a good agreement between the results obtained by the two methods and those reported in literature. Keywords: wood laminated composites, interlaminar fracture, critical strain energy release rate, Double Cantilever Beam (DCB) specimen

This paper presents an experimental study aiming to obtain a new polymer composition by using styrene-butadiene radial block-copolymer with styrene-butadiene diblock-copolymer blend, in order to manufacture masking solution for metal protective coating in the chemical milling process. Keywords: styrene-butadiene block-copolymers, masking solution, protective coating

This paper presents the influence of processing temperature on the physico-mechanical properties of polypropylene (PP) used at the injection molding of performance sport items. The test-pieces were molded at the following real injection temperatures: 220, 240, 260, 280 and 300°C. It was determined that the in-mould pressure decreases with the increase of processing temperature The thermal analysis performed were: TG, DSC and DMA. It was established that the processing temperature influences the thermal stability of the polymer molded at 300°C, but the vitrification temperature and the melting temperature are slightly influenced by the processing temperature. The storage modulus E’ is influenced by the processing temperature and stress frequency. Keywords: polypropylene (PP), injection molding, Thermogravimetry (TG), Differential Scanning Calorimetry (DSC), Dynamic-Mechanical Analysis (DMA)

Poly(amide-imide)/polyaniline blends containing 2% and 10% polyaniline have been prepared by casting the dispersion resulting from the mixture of polyaniline (micrometer size) with poly(amide-imide) in tetrahydrofuran as solvent onto glass plates. Polyaniline has been synthesized by chemical polymerization of aniline in the presence of (NH4)2S2O8 followed by dedoping with ammonium hydroxide. The poly(amide-imide) has been obtained by solution polycondensation of a fluorinated bis(o-aminophenol), 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, with a diacid chloride having imide rings and hexa-fluoroisopropylidene unit, namely 2,2-bis[N-(4-chloroformylphenyl)phthalimidyl]hexafluoropropane. The thermal properties and sensitivity of pure poly(imide-amide) and its blends with polyaniline to vapors of acetone, ethanol and liquefied petroleum gas were investigated. All samples showed high thermal stability, decomposition temperature being above 270°C. They exhibited sensitivity to the tested gases, those containing 10% polyaniline presented the greatest sensitivity to acetone vapors. Keywords: polymer blends, polyaniline, poly(amide-imide), thermal stability, sensors

A phosphorus-containing copoly(ester-amide-imide) has been synthesized by solution polycondensation reaction of an aromatic dianhydride, namely 1,4-[2-(6-oxido-6H-dibenz[c,e][1,2]oxaphosphorin-6-yl)]-naphthalene-bis(trimellitate)dianhydride, with 4,4´-oxydianiline and isophthaloyl chloride. The polymer was easily soluble in polar organic solvents, such as N-methyl-2-pyrrolidone, N,N-dimethylformamide, tetrahydrofuran and chloroform. The polymer shows high thermal stability, the decomposition temperature being above 410 oC. The value of the glass transition temperature was 231oC. Due to the presence of phosphorus, the polymer gave high char yield in thermogravimetric analysis. Keywords: copoly(ester-amide-imide), phosphorus-containing polymer, thermal stability

In this paper, it is showed that a mechanical model with one degree of freedom can be used to study the vibrations of a bar in a certain point. The considered structures were made of epoxy resin reinforced with carbon and carbon-kevlar texture. The vibrations in the free end of the bar, clamped at the other end, were determined experimentally for four different lengths. Eigenfrequencies and damping factor for the first modes of vibration were obtained for each bar. Relationships for the eigenfrequency and damping factor are proposed, as a function of the length of the bar, for each of the studied materials. Keywords: Eigenfrequency, damping factor, composite bar

The paper presents the effects of the miscibility and of the micro-structure on the surface defects of some bio – hybrides based on starch, polyvinyl alcohol (PVOH) and multilayered silicates. At macroscopic level (100m) the studied starch bio-hybrids seem to be compact materials. If these materials are analysed at a microscopic level (10 m) depending on their type surface defects like voids, cracks and fractures can be observed. These defects are not a consequence of a poor miscibility, even in case of bio-hybrids that contain untreated silicate. These defects appear because of the bio-hybrids micro-structure. As the new bio – hybrids are probably disorderly ones, it can be estimated that the surface defects appear as a consequence of a poor distribution of the swollen silicate tectoids into the polymeric matrix, possibly as a consequence of the improper melt processing conditions. Keywords: polyvinyl alcohol, starch, multilayered silicate, surface defects, miscibility, bio-hybrides, micro-structure