Search results for "CONDENSED MATTER"
showing 10 items of 13918 documents
Thermogravimetric and calorimetric studies of water absorbed in polyaniline
1995
Abstract Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to study the behavior of residual water absorbed by an emeraldine base and a salt of chemically synthesized polyaniline (PANI—EB, PANI-ES). The matrix of PANI is shown to contain water molecules participating in both reversible and irreversible absorption. In its turn, the reversibly absorbed water consists of two components. The first component (WD 1 ) amounts to 5–7 wt.% and is removable from PANI-EB in a flow of dry nitrogen at room temperature. The second one (6–8 wt.%) of more strongly bonded water (WD 2 ) can be withdrawn from PANI-EB at temperatures from 70 to 150 °C depending on the measu…
Thermal degradation of highly crosslinked rigid PU-PIR foams based on high functionality tall oil polyol
2019
Abstract This study presents the development and analysis of rigid polyurethane-polyisocyanurate (PU-PIR) foam synthesized from high functionality tall oil (TO) based polyols. Three PU-PIR formulations with varied high functionality TO based polyol content (45, 75 and 95 pbw) and a different tier of isocyanate (NCO) indexes (110, 150, 200, 300 and 400) for each formulation were compared to a formulation developed using conventional raw materials, mainly obtained from petrochemicals. Using the Fourier transform infrared spectral analysis (FTIR), the chemical structure of the foams was evaluated with emphasis on the characteristic PU-PIR signal ratio and isocyanurate signal peaks. The thermal…
Effect of small amounts of poly(lactic acid) on the recycling of poly(ethylene terephthalate) bottles
2011
Abstract Poly(ethylene terephthalate) (PET) is one of the most used commodity polymers, especially for food and beverage applications, and its recycling is of great importance because of the possible use in the textile and construction industries. On the other hand, the interest in biodegradable polymers has led, in recent years, to the use of materials such as poly(lactic acid) (PLA) also in the food and beverage industry. The presence of small amounts of PLA in the PET waste can significantly affect the post-consumer recycling process. In this work, the effect of the presence of small amounts of PLA on the recycling of PET bottles is investigated by rheological, mechanical, morphological …
The effect of silica nanoparticles on the morphology, mechanical properties and thermal degradation kinetics of PMMA
2012
Abstract Silica–PMMA nanocomposites with different silica quantities were prepared by a melt compounding method. The effect of silica amount, in the range 1–5 wt.%, on the morphology, mechanical properties and thermal degradation kinetics of PMMA was investigated by means of transmission electron microscopy (TEM), X-ray diffractometry (XRD), dynamic mechanical analysis (DMA), thermogravimetric analyses (TGA), Fourier-transform infrared spectroscopy (FTIR), 13 C cross-polarization magic-angle spinning nuclear magnetic resonance spectroscopy ( 13 C{ 1 H} CP-MAS NMR) and measures of proton spin-lattice relaxation time in the rotating frame ( T 1 ρ ( H )), in the laboratory frame ( T 1 ( H )) a…
Accelerated ageing due to moisture absorption of thermally cured epoxy resin/polyethersulphone blends. Thermal, mechanical and morphological behaviour
2011
Abstract A model epoxy resin/anhydride system, modified with a polyethersulfone (PES) engineering thermoplastic toughening agent, has been studied under hydrothermal ageing in order to investigate the modification of the thermal, morphological and mechanical behaviour through dynamical mechanical thermal analysis, SEM microscopy and fracture toughness test respectively. Two different concentrations of the toughening agent were used in the blends and two ageing conditions have been considered, consisting of the immersion of the samples in distilled water at constant temperature of 70 °C for 1 week and for 1 month. Dynamical mechanical thermal analysis results on hydrothermally aged materials…
Miscibility of a DGEBA Based Epoxy Resin Blended with Thermoplastic Mixtures of Poly(styrene) and Block Copolymers: Influence of the Copolymer Conten…
2008
The miscibility and phase behavior of ternary systems formed by a DGEBA based epoxy resin, polystyrene (PS), and diblock copolymers has been investigated through phase diagrams experimentally obtai...
Nonisothermal elongational behavior of blends with liquid crystalline polymers
1994
Measurements of melt strength and breaking stretching ratio of several blends of thermoplastic polymers with liquid crystalline polymers are presented. The melt strength behavior depends not only on the viscosity of the blends but also on the temperature dependence of the viscosity. In particular, even if the viscosities of the blends are, at the extrusion temperature, lower than that of the thermoplastic matrices, the melt strength can be larger than that of the pure thermoplastics if its viscosity-temperature curve exceeds that of the matrices far from the solidification temperature. This behavior allows one to spin or film blow these blends despite the low viscosity.
Shear flow characterization of blends containing liquid crystal polymers
1992
A simple phenomenological approach is proposed in order to predict the presence of minima in the viscosity-composition curves of blends of thermoplastic with liquid crystal polymer (LCP). When the viscosity of the liquid crystal polymer is larger than that of the thermoplastic matrix, a minimum is observed. A possible explanation of the presence of yield stress in the flow curves of these blends is also given.
Gamma radiation of EVA-AA/MMA swollen systems to obtain mechanically improved blends
2002
In this work a "new" way to obtain "compatibilised" blends of rubber-glassy thermoplastic components is presented. Polyethylen-vinyl acetate acrylic acid terpolymer is swollen by methylmetacrylate and the system is irradiated through gamma rays in order to induce polymerisation of the monomer. Solubility and dynamic mechanical tests indicate the formation of a two phase system, even though in presence of strong interactions between the two components. Mechanical tensile behaviour is that of a ductile material with appreciable modulus values.
Thermal properties of e-beam cured epoxy/thermoplastic matrices for advanced composite materials
2007
The aim of this work is to investigate the possibility to improve the thermal behaviour of epoxy based systems, cured by ionizing radiation, in order to produce matrices for advanced carbon fibres composites. Blends of two epoxy monomers, difunctional and trifunctional, have been polymerized by e-beam irradiation and the dynamic mechanical thermal properties have been investigated. The increase of the concentration of the trifunctional epoxy monomer in the blend causes a marked increase of the Tg, but strongly decreases the reactivity. Subsequently, blends of the same epoxy monomers with a high Tg thermoplastic toughening agent have been considered and their reactivity and the thermal prope…