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Wyniki wyszukiwania dla: POLYURETHANES
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DETERMINATION OF THE HYDROXYL NUMBER OF GROUND TIRE RUBBER PARTICLES VIA MODIFIED TEST METHOD FOR ISOCYANATE GROUPS
PublikacjaNowadays, considering the environmental trends and law regulations associated with the circular economy, it is very important to seek for the methods of by-products and waste utilization. The example of such material, which requires the attention and recycling method is ground tire rubber generated during recycling of post-consumer car tires. It can be introduced into various polymer matrices as a filler, but to enhance its effectivity...
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Waste tire rubber as low-cost and environmentally-friendly modifier in thermoset polymers – a review
PublikacjaNowadays, waste tire rubber (WTR) management is a growing and serious problem. Therefore, research works focused on the development of cost-effective and environmentally-friendly methods of WTR recycling are fully justified. Incorporation of WTR into polymer matrices and composite materials attracts much attention, because this approach allows sustainable development of industrially applicable waste tires recycling technologies....
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A review: Fabrication of porous polyurethane scaffolds
PublikacjaThe aim of tissue engineering is the fabrication of three-dimensional scaffolds that can be used for the reconstruction and regeneration of damaged or deformed tissues and organs. A wide variety of techniques have been developed to create either fibrous or porous scaffolds from polymers, metals, composite materials and ceramics. However, the most promising materials are biodegradable polymers due to their comprehensive mechanical...
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Sustainable synthesis of cyclic carbonates from bio‐based polyether polyol: the structure characterization, rheological behaviour and thermal properties
PublikacjaThe cycloaddition of CO2 to epoxides represents a green efficient method to form bis(cyclic carbonate)s. The main purpose of the work reported in this paper was to examine the effect of the gas flow rate (20, 40, 60 and 100 mL min–1) during carbonation on the conversion yield, chemical structure, rheological behaviour and thermal properties of the prepared compounds. A series of new bis(cyclic carbonate)s was obtained from bio‐based...
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Degradable poly(ester-ether) urethanes of improved surface calcium deposition developed as novel biomaterials
PublikacjaBones, which are considered as hard tissues, work as scaffold for human body. They provide physical support for muscles and protect intestinal organs. Percentage of hard tissues in human body depends on age, weight, and gender. Human skeleton consists of 206 connected bones. Therefore, it is natural that the hard-tissue damage such as fractures, osteoporosis, and congenital lack of bone may appear. The innovative way of bone healing...
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Bio‐polyols synthesized by liquefaction of cellulose: Influence of liquefaction solvent molecular weight
PublikacjaCurrently, the plastics industry including polyurethanes is based on the use of petrochemicals. For this reason, scientists are looking for new types of renewable resources for the substitution of petrochemical substances. This work aims to evaluate the effect of polyethylene glycols (PEG) with different molecular mass impact on properties of bio-based polyols synthesized via biomass liquefaction of cellulose. To date, research...
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Synthesis, structure and properties of poly(ether-urethane)s synthesized using a tri-functional oxypropylated glycerol as a polyol
PublikacjaThe main aim of this work was to obtain poly(ether-urethane)s using tri-functional polyoxyalkylene polyol (Rokopol G1000), which introducing the chemical cross-links into the structure of polyurethanes. Poly(ether-urethane)s were prepared using two-step method, called prepolymer method, which involves in the first step the reaction of 4,4'-diphenylmethane diisocyanate (MDI) and tri-functional polypropylene glycol glycerol triether...
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Polymers for burn dressings and skin substitutes
PublikacjaSkin burns belong to the group of the most complex injuries due to convoluted skin structure which includes nerve cells, muscles, sweat and sebaceous glands and blood vessels. Both on the market and at the research stage, there are many different dressing and skin substitutes proposals that utilize various materials and active substances. This chapter focuses on summarizing and describing the most popular polymer-based commercial...
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Polyurethane Glycerolysate as a Modifier of the Properties of Natural Rubber Mixtures and Vulcanizates
PublikacjaChemical recycling of polyurethanes can be realized in several different ways, but the most important methods are glycolysis and glycerolysis. Both methods permit recovery of polyols (when the process is realized with the mass excess of depolymerizing agent) or substitutes of polyols, which contain urethane moieties in the main chains and terminate mainly in hydroxyl groups (when the process is realized with the mass excess of...
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Shape-Memory Polyurethane Polymers
PublikacjaPolyurethanes (PUs) are one of the most widely used polymers in research and industry. They can be synthesized from chemical sources and natural sources. PUs are a very useful class of polymers and exhibit many desirable properties that can be exploited in various applications. PUs are formed by the reaction between polyols and isocyanates. A wide variety of polyols and isocyanates are available for synthesis, and hence we can...
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Green TPUs from Prepolymer Mixtures Designed by Controlling the Chemical Structure of Flexible Segments
PublikacjaThis study concerns green thermoplastic polyurethanes (TPU) obtained by controlling the chemical structure of flexible segments. Two types of bio-based polyether polyols—poly(trimethylene glycol)s—with average molecular weights ca. 1000 and 2700 Da were used (PO3G1000 and PO3G2700, respectively). TPUs were prepared via a two-step method. Hard segments consisted of 4,4?- diphenylmethane diisocyanates and the bio-based 1,4-butanodiol...
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Bio polyetherurethane composites with high content of natural ingredients: hydroxylated soybean oil based polyol, bio glycol and microcrystalline cellulose
PublikacjaIn our study, we focused on obtaining bio-polyurethane composites using bio-components such as bio glycol, modified natural oil-based polyol, and microcrystalline cellulose (MCC). The pre-polymer method was used to prepare the bio polyurethane matrix. Prepolymer was synthesized using 4,4’-diphenylmethane diisocyanate (MDI) and a polyol mixture containing 50 wt.% of commercial polyether and 50 wt.% of hydroxylated soybean oil (H3)....
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Morphology, Mechanical and Thermal Properties of Thermoplastic Polyurethane Containing Reduced Graphene Oxide and Graphene Nanoplatelets
PublikacjaPolyurethane/graphene nanocomposites were synthesized using commercial thermoplastic polyurethane (TPU, Apilon 52DE55), and two types of graphene derivatives: graphene nanoplatelets (GNP) and reduced graphene oxide (RGO). Fourier Transformation Infrared Spectroscopy Fourier Transformation Infrared Spectroscopy (FTIR) spectroscopy, TEM, and SEM microscopy and XRD techniques were used to chemically and structurally characterize GNP...
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Insights into Stoichiometry Adjustments Governing the Performance of Flexible Foamed Polyurethane/Ground Tire Rubber Composites
PublikacjaPolyurethanes (PU) are widely applied in the industry due to their tunable performance adjusted by changes in the isocyanate index—stoichiometric balance between isocyanate and hydroxyl groups. This balance is affected by the incorporation of modifiers of fillers into the PU matrix and is especially crucial for PU foams due to the additional role of isocyanates—foaming of the material. Despite the awareness of the issue underlined...
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Microwave radiation in the synthesis of urethane prepolymers
PublikacjaThis paper describes the use of microwave radiation in the synthesis of urethane prepolymers in bulk (without solvent). The prepolymers were synthesized using 1,6-hexamethylene diisocyanate (HDI) and poly (ε-caprolactone) diol (PCL) at a molar ratio of 4:1. The reaction was carried out without a catalyst in the reactor with a conventional heating system (oil bath) or in the microwave reactor (MW Reactor NOVA 09) at temperatures...
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Structure and properties comparison of poly(ether-urethane)s based on nonpetrochemical and petrochemical polyols obtained by solvent free two-step method
PublikacjaThe application of thermoplastic polyurethanes (TPU) is becoming more and more extensive, and the decreasing of used petrochemical monomers and reduction of energy for the polymerization and processing processes is getting increasingly important. In this paper, we confirmed the positive influence of high bio-based monomers contents (by replacing petrochemical polyol and glycol by bio-based counterparts) on processing and properties...
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Biopolyols obtained via crude glycerol-based liquefaction of cellulose: their structural, rheological and thermal characterization
PublikacjaIn this work lignocellulose biomass liquefaction was used to produce biopolyols suitable for the manufacturing of rigid polyurethane foams. In order to better evaluate the mechanism of the process, pure cellulose was applied as a raw material. The effect of time and temperature on the effectiveness of liquefaction and the parameters of resulting biopolyols were characterized. The prepared materials were analyzed in terms of their...
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Fabrication of polyurethane and polyurethane based composite fibers by the electrospinning technique for soft tissue engineering of cardiovascular system
PublikacjaElectrospinning is the unique technique, which provides forming of polymeric scaffolds for soft tissue engineering, which include tissue scaffolds for soft tissues of cardiovascular system. Such artificial soft tissues of cardiovascular system may possess mechanical properties comparable to native vascular tissues. Electrospinning technique gives the opportu nity to form fibres with nm- to μm-scale in diameter. The arrangement...
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Effect of bio-based components on the chemical structure, thermal stability and mechanical properties of green thermoplastic polyurethane elastomers
PublikacjaIt seems to be obvious that conditions changes during polyols synthesis have impact on the polyols properties. Even the chemical formula is the same or similar, physicochemical properties and also molecular weight of polyols might be different and are significant in term of future polyurethanes properties and processing. In this work, fully bio-based poly(propylene succinate)s synthesized at different temperature conditions were...
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The Green Approach to the Synthesis of Bio-Based Thermoplastic Polyurethane Elastomers with Partially Bio-Based Hard Blocks
PublikacjaBio-based polymeric materials and green routes for their preparation are current issues of many research works. In this work, we used the diisocyanate mixture based on partially bio-based diisocyanate origin and typical petrochemical diisocyanate for the preparation of novel bio-based thermoplastic polyurethane elastomers (bio-TPUs). We studied the influence of the diisocyanate mixture composition on the chemical structure, thermal,...
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Polyurethane-based aerogels: Preparation, properties, and applications
PublikacjaPolyurethane aerogels (PUAs) are interesting materials because of their high porosity, low density, and low thermal conductivity, which result in their application as thermal insulations. PUAs are mainly synthesized using di- and polyisocyanates, diols or polyols, catalysts (tertiary amines and organometallic), and solvents (which are used as reaction medium, purifying of obtained semiproducts). Preparation procedure involves several...
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Polyisocyanates from Sustainable Resources
PublikacjaIsocyanates, next to polyols, constitute the major components essential for polyurethane (PU) production. They have a significant impact on physicochemical, mechanical, and thermal properties of PU materials. They also have an impact on those materials’ purposes, forms, textures, and other features. The available and used isocyanates are of a petrochemical origin. With the development of a trend toward green chemistry in the science...
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Microcrystalline Cellulose Management in the Production of Poly(ether-urethane)s- Structure, Morphology, and Thermal Characteristic
PublikacjaIn response to the demand of polymer industry for reducing the use of synthetic chemicals, eco-friendly materials are investigated. In the presented study, bio-based poly(ether-urethane)s were prepared by using microcrystalline cellulose (MCC) and polyether polyol and 1,3-propanediol derived from corn sugar. A step towards sustainability was taken by incorporating bio-based compounds and cellulose, consequently, bio-waste are utilized...
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Evaluation of the glycerolysis process and valorisation of recovered polyol in polyurethane synthesis
PublikacjaIn this study, the glycerolysis of polyurethane (PU) foam and the applicability of obtained glycerolysate (GLY) for cast PUs were investigated. It was found that crude glycerine with purity grade of 84% might be successfully used for the glycerolysis. The optimal conditions were determined as follows: reaction time of 60 min at 220 °C using dibutyltin dilaurate catalyst (0.5%). Moreover, the purification of GLY by means of liquid-liquid...
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Susceptibility to Degradation in Soil of Branched Polyesterurethane Blends with Polylactide and Starch
PublikacjaA very important method of reducing the amount of polymer waste in the environment is the introduction to the market of polymers susceptible to degradation under the influence of environmental factors. This paper presents the results of testing the susceptibility to degradation in soil of branched polyesterurethane (PUR) based on poly([R,S]-3-hydroxybutyrate) (R,S-PHB), modified with poly([D,L]-lactide) (PLA) and starch (St). Weight...
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Nonlinear Viscoelastic Properties of Polyurethane Nanocomposites
PublikacjaIn recent years, the nonlinear viscoelastic behaviors of elastomeric nanocomposites have been examined, especially for a wide range of rubbery composite (including natural rubber) materials. This chapter describes the influence of fillers and nanofillers on the nonlinear viscoelastic properties of elastomeric polyurethane systems. These filled elastomers (similar to the classic natural rubber reinforced elastomers), also exhibit...
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Elastic polyurethane foams containing graphene nanoplatelets
PublikacjaElastic polyurethane foams were produced from two-component polyurethane systems (SPECFLEX NE 113 izocyjanian/NR 816 poliol system—SPC and Elastic MBMarket company system POLYOL ET MB 500/ISO ET MB 800—ET) by using a one-step method. The foams were a graphene nanoplatelets (GNP) in the amount ranging from 1 to 2 wt.%. The effect of the nanofiller on polyurethane matrix was determined by analyzing the chemical structure, static...
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Effect of Variation of Hard Segment Content and Graphene-Based Nanofiller Concentration on Morphological, Thermal, and Mechanical Properties of Polyurethane Nanocomposites
PublikacjaThis study describes the development of a new class of high-performance polyurethane elastomer nanocomposites containing reduced graphene oxide (RGO) or graphene nanoplatelets (GNP). Two types of polyurethane elastomers with different contents of hard segments (HS) were used as a polymer matrix. The developed nanocomposites were characterized by thermal analysis (DSC, TG), dynamic mechanical testing (DMA), hardness testing, mechanical...