Mixture Of Polyurethane Research Articles

Study on temperature dependence of catalytic thermal decomposition of polyamides and polyurethanes mixed with acidic zeolites

Waste electric and electronic equipments (WEEE) and automotive plastic shredder contain nitrogen-containing polymers such as polyamides and polyurethanes. Thermal decomposition of these polymers leads to pyrolysis oil in which unwanted N-containing compounds are also present. Catalytic pyrolysis can be a way to reduce the oil's N-content or to obtain valuable products. We have examined the slow heating rate pyrolysis of zeolite–polyamide and zeolite–polyurethane mixtures by thermogravimetry-mass spectrometry (TG-MS), moreover flash pyrolysis of the mixtures at three different temperatures were carried out by pyrolysis-gas chromatography mass spectrometry (Py-GC/MS). In TG-MS experiments thermal decomposition characteristics of polyamides are hardly affected by the presence of acidic zeolites, nevertheless, MS ion curves show that the nature of the evolved volatile compounds have changed considerably. Similarly different pyrolysis products have been obtained from pure polyurethanes and polyurethane–zeolite mixtures, but polyurethane–zeolite mixtures have noticeably dissimilar thermal behaviour than the pure polymer. Py-GC/MS measurements have revealed that the pyrolysis temperature significantly affects the pyrolysis product distribution of the investigated polymers and also that of their mixtures with acidic zeolites. For zeolite–polyamide-6,6 1:1 mixtures it was concluded that hexanedinitrile is the main pyrolysis product and its predominance is the highest at 500°C. Main pyrolysis products of zeolite–polyamide-6 mixtures of 1:1 ratio are dihydro-azepine isomers. Their amount does not increase over 450°C, however with rising temperature aromatic compounds are also formed. In case of polyurethane–zeolite mixtures the ether and ester segments are decomposed mainly to monomers, while diisocyanate units are converted to N-containing aromatic compounds. The amount of these compounds is varying with temperature, moreover increasing the pyrolysis temperature (450°C or higher) the formation of aromatic hydrocarbons (benzene and naphthalene compounds) and light unsaturated hydrocarbons are favoured. Flash pyrolysis of polyurethane–NH4Y zeolite mixtures indicated that ammonia notably affects the decomposition of polyester segments leading to hexanedinitrile formation at as low temperature as 400°C.

Morphology and structure of antibacterial nanocomposite organic–polymer and metal–polymer coatings deposited from active gas phase

The synthesis of nanocomposite polymer-based coatings was produced from active gas phase formed by electron beam dispersion of polymer and biocide agent in vacuum. The features of thin nanocomposite coatings formation from an active gas phase and their molecular structures were defined. Possibility of vacuum deposition of organic–polymer coating containing ciprofloxacin with antibacterial properties was stated. It was shown that during electron-beam dispersion of mechanical mixtures of ciprofloxacin and polyurethane, ciprofloxacin and polyethylene powders there is no appreciable radiation-thermal degradation of the initial chemical compounds. Polymer matrix of such thin-layer systems permits to control the release of the biocide agent in isotonic sodium chloride solution. For the coatings containing silver nanoparticles, the antibacterial action on test microorganisms including drug resistant bacteria was defined.

Catalytic thermal decomposition of polyamides and polyurethanes mixed with acidic zeolites

The purpose of this work was to examine the pyrolysis products derived from zeolite–polyamide and zeolite–polyurethane mixtures prepared in different ratios in order to elucidate the chemical reactions taking place under pyrolysis of these polymers in the presence of acidic Y zeolites (ultra stabilized HY (HUSY) and NH4NaY). Therefore 5:1, 3:1, and 1:1 ratios of zeolite and nitrogen-containing polymer (polyamides and polyurethanes) mixtures were pyrolysed at 500°C in a micro-pyrolyser on-line coupled with GC/MS. The products and product distribution of zeolite–polymer mixtures indicate that the amount of catalysts significantly affects the pyrolysis product distribution. In case of zeolite–PA-6,6 1:1 mixtures hexanedinitrile is the main pyrolysis product indicating that the thermal decomposition of PA-6,6 via cis-elimination is enhanced. Main pyrolysis products of zeolite–PA-6 mixtures of 1:1 ratio are dihydro-azepine isomers that are the dehydrated derivatives of ɛ-caprolactam. Pyrolysis of 1:1 zeolite–PA-12 mixtures leads to the promoted formation of dehydrated cyclic monomer isomers (azacyclotrideca-dienes). For zeolite–PUR 1:1 mixtures it was concluded that MDI decomposition to N-containing aromatics is enhanced, while the polyester and polyether segments degrade to monomer type products and to aromatics. For all zeolite–polymer mixtures increasing ratio of catalysts leads to increased amount of aromatics (benzene and naphthalene compounds) and light unsaturated hydrocarbons, while the amount of main products of 1:1 mixtures decreases.

Simulation based estimation of dynamic mechanical properties for viscoelastic materials used for vocal fold models

In order to obtain a deeper understanding of the human phonation process and the mechanisms generating sound, realistic setups are built up containing artificial vocal folds. Usually, these vocal folds consist of viscoelastic materials (e.g., polyurethane mixtures). Reliable simulation based studies on the setups require the mechanical properties of the utilized viscoelastic materials. The aim of this work is the identification of mechanical material parameters (Young's modulus, Poisson's ratio, and loss factor) for those materials. Therefore, we suggest a low-cost measurement setup, the so-called vibration transmission analyzer (VTA) enabling to analyze the transfer behavior of viscoelastic materials for propagating mechanical waves. With the aid of a mathematical Inverse Method, the material parameters are adjusted in a convenient way so that the simulation results coincide with the measurement results for the transfer behavior. Contrary to other works, we determine frequency dependent functions for the mechanical properties characterizing the viscoelastic material in the frequency range of human speech (100–250 Hz). The results for three different materials clearly show that the Poisson's ratio is close to 0.5 and that the Young's modulus increases with higher frequencies. For a frequency of 400 Hz, the Young's modulus of the investigated viscoelastic materials is approximately 80% higher than for the static case (0 Hz). We verify the identified mechanical properties with experiments on fabricated vocal fold models. Thereby, only small deviations between measurements and simulations occur.

Thermal performance of a mobile home with light envelope

The present work analyzes, through in situ measurements, the environmental parameters of a mobile home (camper type van) characterized by a light envelope, located in Southern Italy. Through dynamic simulation, using EnergyPlus software, a few strategies to improve the inside conditions are then proposed and verified. The solution that best improves the indoor microclimate is forced ventilation combined with shading providing by simple roofing. Three envelope solutions were also analyzed: a low thermal mass (polyurethane foam), a high thermal mass (phase change material, PCM), and a medium thermal mass (mixture of polyurethane foam and PCM) solution. The material that improves the inside conditions appears to be the high thermal mass solution (pure PCM), while the mixture of polyurethane and PCM has a performance similar to that of pure polyurethane.

Polyurethane unimorph bender microfabricated with Pressure Assisted Microsyringe (PAM) for biomedical applications

This paper describes a new microfabrication technique for bender-type electromechanical actuators made of an elastomeric electroactive polymer. The technique is based on a computer-controlled deposition of the active material with a microsyringe. The paper describes the developed microfabrication system and proposes a simple deposition model. The realization of solid-state unimorph bender actuators made of polyurethane as electrolyte and a mixture of carbon black and polyurethane as electrodes is presented. Prototype actuators fabricated both with the new technique were driven with electrical field of 100 V/μm and showed bending angles higher than 30°. In this way, we have demonstrated that it is possible to fabricate polyurethane based microactuators using a polyurethane/carbon black composite such as device.

Morphological and physical properties of a thermoplastic polyurethane reinforced with functionalized graphene sheet

AbstractBACKGROUND: Functionalized graphene sheet (FGS) was recently introduced as a new nano‐sized conductive filler, but little work has yet examined the possibility of using FGS as a nanofiller in the preparation of polymer nanocomposites. In particular, there are currently no published papers that evaluate polyurethane/FGS nanocomposites. The purpose of this study was to prepare a polyurethane/FGS nanocomposite and examine the morphological and physical properties of the material.RESULTS: A cast nanocomposite film was prepared from a mixture of thermoplastic polyurethane (TPU) solution and FGS suspended in methyl ethyl ketone. The FGS dispersed on the nanoscale throughout the TPU matrix and effectively enhanced the conductivity. A nanocomposite containing 2 parts of FGS per 100 parts of TPU had an electrical conductivity of 10−4 S cm−1, a 107 times increase over that of pristine TPU. The dynamic mechanical properties showed that the FGS efficiently reinforced the TPU matrix, particularly in the temperature region above the soft segment melt.CONCLUSION: Our results show that FGS has a high affinity for TPU, and it could therefore be used effectively in the preparation of TPU/FGS nanocomposites without any further chemical surface treatment. This indicates that FGS is an effective and convenient new material that could be used for the modification of polyurethane. It could also be used in place of other nano‐sized conductive fillers, such as carbon nanotubes. Copyright © 2009 Society of Chemical Industry

Use of microorganisms immobilized on composite polyurethane foam to remove Cu(II) from aqueous solution

Composite polyurethane (PU) foams were made via the polymerization of toluene diisocyanate (TDI) and polyether polyol with activated carbon fiber, and immobilized microorganisms on polyurethane (IPU) foam were prepared by cultivating the microbe B350 in a mixture of culture medium and PU. We used batch adsorption techniques to study the removal of Cu(II) ions from aqueous solutions via PU and IPU. Moreover, the effects of pH, temperature, carrier amount, and biosorption time on the removal rate of Cu(II), adsorption equilibrium, and adsorption kinetics were investigated in detail. The IPU showed an excellent removal rate for Cu(II). The adsorption kinetics data were in good agreement with the pseudo-second-order rate model, and the adsorption isotherms could be adequately described by the Langmuir equation. For synthetic wastewater containing Cu(II), the removal rates for Cu(II) and COD after 4 h treatment were 85% and 80%, respectively.

Multilayer radar absorbing material processing by using polymeric nonwoven and conducting polymer

This study shows the processing of radar absorbing multilayer structures based on nonwoven substrates of polyacrylonitrile and poly (ethylene terephthalate) impregnated with a polyaniline and polyurethane mixture. Processed materials with different parameters - layer stacking and impregnated faces - were evaluated considering the incident radiation attenuation in the frequency range of 8 to 12 GHz. The results show the influence of the quantity, types and thickness of the impregnated layers. Scanning electronic microscopy observations evaluated the anchorage of the absorbing center (polyaniline) in the substrate. In a general way, the different obtained structures presented incident radiation attenuation values between 87 and 99%. This result allows its use as microwave absorbers.

A New Polyurethane/Heparin Vascular Graft for Small-Caliber Vein Repair

Small-caliber (1.2 mm inner diameter) vein grafts, made from a mixture of heparin and polyurethane with superior compliance, excellent antithrombogenicity and biocompatibility, have been developed. Eighteen rabbits were used; 12 for the heparin containing grafts and the other six were pure polyurethane grafts as controls. Each graft segment (2 cm in length) was implanted into the femoral veins using a newly developed anastomosis method. Sodium heparin was given before surgery, but no anticoagulant was used thereafter. All the rabbits lived during the whole experimental period of 1 year. Histological analyses of vessels retrieved 2, 4, 8, 12 and 24 weeks after implantation revealed regeneration of endothelial-like cells (in 2 weeks), elastin-like tissues (in 8 weeks), and neoadventitia-like layers (in 12 weeks). The patency rate for the heparin containing grafts was 100%, but was only 83.3% in the no heparin controls. These results indicate that “ideal” small diameter blood vessels can be synthesized and used directly without cellularization before implantation. By the properly selecting scaffold materials, a native vein can repair itself spontaneously to certain degree.

Polyurethane coating for protecting concrete floors using the system with fillers produced by recycling

The top layer of the systems covering a concrete surface is made of polyurethane. The polyurethane layer should be characterized by high tensile strength and abrasive wear resistance, because this material is used in workshops, corridors, and warehouses. Up till now the systems have been a mixture of polyurethane and different fillers. The recyclate from polyurethane waste added to the systems can modify their properties. Our purpose was to produce and to test the composites supplemented with recyclates of different hardness. The influence of the proportion of wastes on the composite properties was investigated as well. As a result we obtained the materials of higher resistance to abrasive wear and of higher values of Young's modulus and with unchanged resistance to tensile strength, ultimate elongation and bending. Furthermore a permanent deformation of the materials tested was decreased. The recyclates of the 50°ShD hardness increase the abrasive wear resistance of compasites by 50%, whilst the cost of the material is reduced.

Combustion Characteristics and Pollutant Control by Eco-fuel from Polyurethane Foam

Around the world, thousands of tons of polyurethane (PU) foam waste accumulate in municipal dumps from sources such as car disposal industries. Due to its low density and high volume, polyurethane foam waste is difficult to treat and dispose of in landfill. In this study, we developed a novel and environmentally friendly disposal method for PU waste by mixing it with coal to produce a new composite fuel called Eco-fuel. Eco-fuel is made by briquetting a mixture of PU with coal (10:90 by weight) under high pressure. The combustion characteristics and emission gases of Eco-fuel were compared with those of biobriquette (a 20:80, by weight, briquette of biomass and coal). The combustion characteristics of Eco-fuel briquette fuel were improved with the addition of PU foam. Although PU has a higher nitrogen content (6 wt %) compared to biomass (1.4 wt %) and coal (1 wt %), the emission of NOx from the combustion of Eco-fuel did not increase. We discovered that the combustion of PU results in the conversion of n...

Synthesis, properties, and dyeing application of nonionic waterborne polyurethanes with different chain length of ethyldiamines as the chain extender

AbstractThis study deals with the synthesis of some nonionic waterborne polyurethanes (PUs), using ethyldiamines of different chain length, such as ethylenediamine (EDA) and diethyltriamine (DETA), as the chain extender in the reaction, and examines the thermal properties, mechanical properties, and dyeing properties of the PU products and their blends. As far as each PU by itself is concerned, we found that the Tg of the one made with DETA is the highest, followed by that with EDA, and the one with 1,4‐butanediol (1,4‐BD) is the lowest. The PU made with 1,4‐BD as the chain extender has no Tm, while the two others, using diamines as chain extenders, have a clear Tm, the one with DETA being higher than that with EDA. However, the enthalpy data are just the opposite. The tensile strengths of the two PUs, made with diamines as the chain extender, are larger than that made with 1,4‐BD, but their respective elongation properties are just the opposite. A comparison within PUs made with diamines showed that the one made with EDA is greater in both strength and elongation categories than that made with DETA. However, the one made with DETA is far superior to both of those made with 1,4‐BD and EDA in their dye‐exhaustion ratio, color yield (K/S), fixation rate, and color fastness. In respect to the various PU mixtures that we examined, we found that both PUs synthesized with EDA or DETA as the chain extender would have their Tg's greatly increased by blending in some PU made using 1,4‐BD as the chain extender. Among them, in particular, a blend of PU, made separately with DETA and 1, 4‐BD as the chain extender, showed great improvements in both tensile strength and elongation and also demonstrated better dyeability. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2824–2833, 2003

Urethane oligomers as raw materials and intermediates for polyurethane elastomers. Methods for synthesis, structural studies and analysis of chemical composition

Based on earlier models developed for polyaddition of diisocyanates and polyols, a non-stoichiometric process was provided for step-by-step polymerisation of 2,4- and 2,6-tolylene diisocyanate (TDI) with diols which had various molecule sizes and the nature of polyethers and polyesters. Said process yielded urethane oligomers which had –NCO or –OH groups as their chain end groups. After elimination of excess monomer, these compounds were—at subsequent stages (2–5)—subjected to further reaction with diisocyanate or with selected polyol. The process was operated in bulk and excess monomers were eliminated with the use of the selective extraction method. Linear products were obtained in that way which had well defined chain structures and narrow distribution of their molecular weights (MWD) PD= M ̄ w / M ̄ n =1.1–1.3. On the basis of IR and mass spectrometry (MS) (electrospray ionization (ESI) and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF)) structural analyses, the expected structures of oligomers were confirmed and the actual compositions of polyurethane mixtures formed at every stage of the polymerisation process could be verified against the data obtained from the model, from the balance calculations (based on determinations of free isocyanate groups) and from the findings of the gel-permeation chromatography (GPC) analysis. Applicability of the presented method was demonstrated and the general scheme was suggested for the process discussed.

Gravure‐printed colour indicators for monitoring Kimchi fermentation as a novel intelligent packaging

AbstractGravure‐printed colour indicators on common nylon/polyethylene (Ny/PE) films were newly developed for kimchi (fermented vegetable products in Korea) packaging to examine the degree of fermentation of such products non‐destructively during distribution and sale. A printing ink consisting of Ca(OH)2 as a CO2 absorbent, bromocresol purple (BP) or methyl red (MR) as a chemical dye, and a mixture of polyurethane and polyester dissolved in organic solvents as a binding medium, was applied on Ny films by the gravure process and then laminated with PE films to form the printed indicator. During storage at 0, 10, 20°C, kimchi fermentation was assessed for titratable acidity (TA), and the colour of the indicators was determined as Hunter values and expressed as total colour difference (TCD). Although TCD value of the BP type indicator was slightly less than that of the MR type, colour changes in both the types of indicator correlated well to TA values of kimchi. The results suggest that gravure‐printed colour indicators have great potential as an intelligent packaging system for monitoring the ripeness of commercial kimchi products. Copyright © 2002 John Wiley & Sons, Ltd.

Development of a generic microelectrode array biosensing system

A new type of electrochemical cell has been developed for use in biosensor applications. Utilising a random array of platinum microdiscs as the working electrode, it incorporates a Ag/AgCl reference electrode and platinum auxiliary electrode into the tip of a polished glassy Teflon probe. Immobilisation of the biochemical moiety onto the surface of the probe is achieved using a mixture of polyurethane (PU) and polyethylene oxide (PEO). Enclosing the tip of the probe within a dialysis membrane completes the electrochemical cell. The hydrophilic nature of the PU–PEO mixture ensures the biochemical moiety is trapped in a stable, hydrophilic environment. The result is an all in one generic electrochemical sensor that can be used in a wide range of biosensor applications in both batch or flow injection modes. The unique features of this system are demonstrated in this paper using the glucose — glucose oxidase (GOD) system. Parameters affecting sensor performance were investigated in both batch and flow injection modes. In terms of sensitivity, reproducibility, equilibration time and linear dynamic range, the performance of the microdisc based sensing system was superior to similar macroelectrode versions. Practical detection limits (0.1 μM) were four–five orders of magnitude better for this system compared with a conventional electrode system. The advantages of using this system in flow injection mode, particularly in terms of increased linear range, were also addressed. The overall linear range of our system (0.1 μM–60 mM) is three–four orders of magnitude greater than the conventional electrode system.

Polyurethane + polyacrylate latex mixtures: Synthesis, characterization and properties

A series of polyurethane + polyacrylate latexes has been synthesized by putting different quantities of polyacrylate dispersion into an acetone solution of an anionic polyurethane prepolymer with terminal isocyanate groups. Colloid-chemical and rheological properties of these systems have been investigated. The sorption of solvent vapors by mixtures of polyurethane + polyacrylate latexes has been studied. Some thermodynamical parameters including partial Gibbs functions of the solvent, individual polymers and their mixtures, and the Gibbs function of mixing polyurethane ionomer and acrylate copolymer have been calculated. Structureproperties relationships of the polyurethane + polyacrylate latexes were studied by dynamic mechanical analysis. Effects of varying the composition on the mechanical properties have been determined.

Effect of fillers on thermal and mechanical properties of polyurethane elastomer

The effects of five different types of fillers on the thermal and mechanical properties of hydroxyl-terminated polybutadiene-based polyurethane elastomers were explored to develop a filled polyurethane elastomeric liner for rocket motors with hydroxyl-terminated polybutadiene-based composite propellants. Two type of carbon black, silica, aluminum oxide, and zirconium(III) oxide were used as filler. Based on the improvement in the tensile properties and the erosion resistance achieved in the first part of the study, an ISAF-type carbon black was selected to be used as the main filler in combination with an additional filler. The second part involves the investigation of polyurethane elastomers containing a second filler in various amounts in addition to the ISAF-type carbon black used as the main filler. In addition to the thermal and mechanical properties, the processability of the uncured polyurethane mixtures were also explored by measuring the viscosity in this second part of the study. The studied fillers do not considerbly change the thermal degradation temperatures and the thermal conductivity of the polyurethane elastomers with a filler content up to 16 wt %. The best improvement in the erosion resistance and tensile strength of the polyurethane elastomers with additional fillers is also achieved when filled with the ISAF-type carbon black, whereas the use of zirconium(III) oxide as additional filler provides almost no improvement in these properties. Viscosity of the uncured polyurethane mixtures increases with the increasing filler content and with the decreasing particle size of the filler. Aluminum oxide-filled elastomers seem to be the most suitable compositions having sufficiently high thermal and mechanical properties, together with the processability of uncured mixtures. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1057–1065, 1998

Polyurethane/polyethyl acrylate interpenetrating polymer networks

The thermal decomposition kinetics of polyurethane/polyethyl acrylate interpenetrating polymer networks (PU/PEA IPN) were studied by means of thermogravimetry and derivative thermogravimetry (TG-DTG), and compared with those of polyurethane (PU) and polyethyl acrylate (PEA). The decomposition temperature (T i) of PU/PEA IPN was found to be higher thanT i of PEA, but lower thanT i of PU. Thermal decomposition kinetic parameters,n andE, estimated using Coats-Redfern method, are found for PU/PEA IPN, PU and PEA to be 1.6, 1.9 and 1.1, and 196.6, 258.6 and 139.2 kJ mol−1, respectively. The results show that PU/PEA IPN is neither a simple mixture of PU and PEA nor a copolymer of them. The mechanism of thermal decomposition of PU/PEA IPN is different from those of PU and PEA. The special network in PU/PEA IPN effectually protects weak bonds in the molecular chain of PU and PEA.

Rapid detection of hyperglycaemia by a subcutaneously-implanted glucose sensor in the rat

The relationship between the concentration of polymer in the coat of an electrochemical glucose sensor and the lag time between changes in blood glucose and sensor output was explored. Sensors designed to be highly permeable to glucose were coated with a polyurethane mixture diluted 1:6·7 (15%) in trichloroethane. Coats of those designed to be less permeable were diluted 1:2·5 (40%). The in vitro response of the 40% sensors, but not of the 15% sensors, was nearly linear up to a glucose level of 56 mM. When tested in 10 rats, the response of the 15% sensors to injected glucose was much more rapid than that of the 40% sensors. The time difference between the peak blood glucose level and peak sensor output was also much smaller for the 15% sensors. In conclusion, use of an electrochemical glucose sensor with high permeability to glucose demonstrates that glucose in the intravascular space equilibrates very rapidly with the subcutaneous space.