Search results for "Urethane"
showing 10 items of 78 documents
The effect of partial exfoliation of multilayer silicate filler particles on the elastic properties of a polymer composite
2018
Abstract A method for stepwise calculation the elastic constants of a three-phase composite, including the polymer matrix, the fully exfoliated silicate nanolayers and the platelike silicate particles in the form of multilayer intercalated stacks is considered. A theoretical analysis is carried out by using the Mori–Tanaka theory of an equivalent medium. The influence of degree of exfoliation (the ratio of exfoliated filler content to the total filler content) on the reinforcing efficiency is studied and discussed. A comparative analysis of experimental data of elastic modulus for a rigid polyurethane/montmorillonite composite and prediction results is carried out. It is shown, that with gr…
Bio-based rigid high-density polyurethane foams as a structural thermal break material
2020
Abstract Sustainable development of building industry implies increasing usage of green materials. With this aim and for the intended application as a structural thermal break material, rigid high-density polyurethane foams have been manufactured using polyols derived from renewable resources - tall oil fatty acids. Thermal conductivity, compressive strength and stiffness of the foams of density ranging from ca. 100 to 680 kg/m3 have been determined. Comparison of the bio-based foams with reference foams derived from petrochemical resources demonstrated similar performance characteristics thus suggesting that bio-based foams can also serve as structural thermal break materials. Analytical m…
Synthesis, modelling and characterisation of novel non-linear optical polymer containing indandionylpyridinium betaine units
1999
Abstract In the present article we report about the synthesis, quantum chemical model calculations and non-linear optical characterisation of a novel polyurethane based polymer — a bipolar organic compound N -(indan-1,3-dion-2-yl)-4- N ′, N ′-dialkyaminopyridinium betaine (IPB) containing charged electron donor and electron acceptor groups covalently bonded to polyurethane polymer backbone. This newly synthesised IPB containing polymer can be regarded as a promising thermally stable organic non-linear optical material with a long time performance for photonics applications.
Estimation of the elastic constants of highly porous cellular plastics reinforced with fibres embedded in foam struts
2015
In order to enhance the mechanical properties of polymer foams, fillers of different materials and sizes are being applied. Fibrous fillers shorter than the characteristic foam cell dimensions have the potential of efficient reinforcement, due to their high aspect ratio, without detrimentally interfering with foam structure. A theoretical model is developed for evaluation of the effect of filler on foam stiffness. The elastic response of rigid polymer foams filled with short fibres, of length commensurable with that of foam struts, is modelled by using the orientational averaging technique. Explicit expressions for components of the stiffness tensor of composite foams are derived in terms …
Supercritical-fluid extraction of chlorofluoroalkanes from rigid polyurethane foams
1996
Abstract Preliminary results about a process for recovering expanding agents chlorofluoroalkanes (CFCs) both trapped in the cavities and dissolved in the polymer from rigid polyurethane foams are reported. The performances of liquid and supercritical carbon dioxide, and of CO2-propane supercritical mixtures were compared. Better results in terms of extraction time and amount of extracted CFCs were obtained with finely ground materials and supercritical propane-carbon dioxide fluids.
Synthesis of reactive hyperbranched and star-like polyethers and their use for toughening of vinylester–urethane hybrid resins
2004
A vinylester – urethane hybrid resin (VEUH) was toughened by adding various vinyl-functionalized branched polyethers in 10 and 20 wt%. Two sets of hyperbranched polymers (HBPs) with different branching density were compared with a set of six-arm star polymers. Besides the architecture, the polymers also varied in their characteristics (molecular mass and mass distribution, vinyl/hydroxy ratio). The morphology of the modified VEUH was studied by dynamic-mechanical thermal analysis (DMTA), transmission (TEM) and scanning electron microscopy (SEM). The toughness was characterized by the fracture energy ðGcÞ determined on compact tension specimens at room temperature. It was established that th…
NLO Polymers Containing as Active Chromophore in Dandionylpyridinium, Betaine Units: Synthesis, Modeling and Characterization
2000
In present article we report about synthesis, quantum chemical model calculations, non-linear optical characterization and dependencies of the surface potential changes on irradiation with light of novel polyurethane based polymers, namely a bipolar organic compound N-(indan-1,3-dion-2-y1)-4-N’,N’dialkylaminopyridinium betaine (IPB) containing charged electron donor and electron acceptor groups covalently bonded to polyurethane polymer backbone. These newly synthesized IPB containing polymers could be regarded as a promising thermally stable organic non-linear optical materials with long time performance for photonic applications.
Enhanced polyurethanes based on different polycarbonatediols
2012
Segmented thermoplastic polyurethanes (PUs) were prepared from 4,4′-diphenylmethane diisocyanate (MDI), 1,4-butanediol (BD) and different macrodiols with a molar mass of 1000. Properties of those PUs based on polycarbonatediol (PCD) were compared with their homologous based on polyesterdiol and polyetherdiol as macrodiols. The proportion used in this study was macrodiol:BD:MDI = 1:2:3, in mole ratio. The hard segment weight percentage is 48 wt% for different PUs. Thermogravimetric analysis, differential scanning calorimetry, differential mechanical analysis, Fourier transform infrared-attenuated total reflection spectroscopy, as well as mechanical properties and retention on flexural prope…
Influence of Nanoclay Additive on Mechanical Properties of Bio-Based Polyurethane Nanocomposites
2013
This paper is about investigation of the bio-based polyurethanes from the rapeseed oil polyols and their modification with montmorillonite nanoparticles. The results of hardness and tensile properties investigation of polyurethane / montmorillonite nanocomposites are presented.
Topochemische reaktionen von monomeren mit konjugierten dreifachbindungen. II. Mitt.: Eine topochemische farb- und vernetzungsreaktion bei polymeren …
1970
Es wurden kristallisationsfahige Polymere mit zwei konjugierten CC-Dreifachbindungen im Grundbaustein hergestellt und ihre Reaktionsfahigkeit im kristallinen Zustand untersucht. Die Polyurethane aus 2.4-Hexadiin-1.6-diol (I) bzw. 3.6.13.16-Tetraoxa-octadeca-8.10-diin-1.18-diol (II) und Hexamethylendiisocyanat sowie der Polyester aus I und Adipoylchlorid farben sich beim Belichten mit UV-Licht oder beim Tempern unterhalb ihres Schmelzpunktes tief rot und werden dabei unloslich. Die Reaktion kann durch Radikaldonatoren katalysiert und durch Radikalfanger inhibiert werden. Die gelosten Polymeren zeigen keine Reaktivitat in dieser Hinsicht. Die Verfarbung und Vernetzungsreaktion kann in Analogi…