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Journal articles on the topic 'Polyurethanes'

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Author: Grafiati
Published: 4 June 2021
Last updated: 1 August 2024

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1

Zych, Krzysztof, Robert Pełech, and Zbigniew Czech. "Thermal degradation of poly(alkyl methacrylates) and polyurethane pressure-sensitive adhesives." Polish Journal of Chemical Technology 12, no. 4 (January 1, 2010): 40–43. http://dx.doi.org/10.2478/v10026-010-0048-4.

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Thermal degradation of poly(alkyl methacrylates) and polyurethane pressure-sensitive adhesives Gas chromatography, coupled with the temperature controlled pyrolysis technique, can be used as a quick method of identification of polymers such as acrylates, methacrylates and polyurethanes. Polymers based on alkyl methacrylates are widely used as construction materials and coatings. Polyurethanes are widely used as self-adhesives, sealants and electrical products (due to polyurethane's low glass transition temperature Tg). The aim of this work is to investigate which products can be obtained from polymethacrylates and polyurethanes.
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2

Zagożdżon, Izabela, Paulina Parcheta, and Janusz Datta. "Novel Cast Polyurethanes Obtained by Using Reactive Phosphorus-Containing Polyol: Synthesis, Thermal Analysis and Combustion Behaviors." Materials 14, no. 11 (May 21, 2021): 2699. http://dx.doi.org/10.3390/ma14112699.

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Phosphorus-containing polyol applications in polyurethane synthesis can prevent volatilization of flame retardants and their migration on the surface of a material. In this work, novel cast polyurethanes were prepared by a one-step method with the use of different amounts of phosphorus-containing polyol, 4,4′–diphenylmethane diisocyanate and 1,4-butanediol. The chemical structure, thermal, physicochemical and mechanical properties and flame resistance of the prepared materials were investigated. The results obtained for cast flame-retarded polyurethanes were compared with cast polyurethane synthesized with commonly known polyether polyol. It has been shown that with an increasing amount of phosphorus content to polyurethane’s chemical structure, an increased flame resistance and char yield were found during combustion tests. Phosphorus polyol worked in both the condensed (reduced heat and mass exchange) and gas phase (inhibition of flame propagation during burning). The obtained materials contained phosphorus polyol, indicating higher thermal stability in an oxidative environment than an inert atmosphere.
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3

Schmidt and Eschig. "Hydrophobilization of Furan-Containing Polyurethanes via Diels–Alder Reaction with Fatty Maleimides." Polymers 11, no. 8 (July 31, 2019): 1274. http://dx.doi.org/10.3390/polym11081274.

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We describe new hydrophobic functionalized linear polyurethane resins by combining N-alkyl maleimides via the Diels–Alder reaction with linear furan-modified polyurethanes. This procedure provides the opportunity for the post-polymerization-functionalizing of polyurethanes. Access to furan-bearing polyurethanes is achieved via the reaction of a furan-containing diol, polyethylenglycol (PEG), and different diisocyanates. The furan-containing diol is obtained from the reaction of furfurylamine and two equivalents of hydroxyalkyl acrylate. The resulting furan-bearing polyurethanes are reacted with fatty amine-based N-alkyl maleimides. The maleimide and furan functionalities undergo a Diels–Alder reaction, which allows for the covalent bonding of the hydrophobic side chains to the polyurethane backbone. The covalent bonding of the hydrophobic maleimides to the polyurethane backbone is proven by means of NMR. The influence of the functionalization on the surface properties of the resulting polyurethane films is analyzed via the determination of surface energy via the sessile drop method.
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4

Carbonell-Blasco, Pilar, Iulian Antoniac, and Jose Miguel Martin-Martinez. "New Polyurethane Sealants Containing Rosin for Non-Invasive Disc Regeneration Surgery." Key Engineering Materials 583 (September 2013): 67–79. http://dx.doi.org/10.4028/www.scientific.net/kem.583.67.

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Different polyurethane sealants were prepared by reacting methylene dyísocyanate and polyadipate of 1,4 butane diol (Mw : 2500 daltons) by using the prepolymer method and different mixtures of rosin and 1,4 butane diol were used as chain extenders. The polyurethanes were characterized by plate-plate rheology, molecular weight distribution, Differential Scanning Calorimetry (DSC), and Laser Confocal Microscopy. The tack of the polyurethanes sealants was obtained by using a modified probe tack method, and their adhesion was obtained by T-peel test of leather/polyurethane sealant/leather joints and by single lap-shear tests of aluminium/polyurethane sealant/aluminium joints. Depending on the rosin content in the chain extender the structure of the polyurethanes was different, i.e. more urethane and urethane-amide hard segments were created up to 50 eq% rosin in the chain extender, and separation of domains was prevailing in the polyurethanes with higher rosin content. Furthermore, the addition of rosin caused an increase in the length of the polymer chains and in the storage modulus (particularly in the polyurethane containing 50 eq% rosin), and decrease in the melting enthalpy. Moreover, the crystallinity of the polyurethanes containing up to 50 eq% rosin showed lower number and smaller spherulites, Finally, the tack at 37 °C and the peel strength increased in the joints made with the polyurethane sealants containing rosin whereas the adhesive shear strength decreased when the polyurethane sealant contained 50 eq% rosin or less.
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5

Domańska, Agata, Anna Boczkowska, Marta Izydorzak-Woźniak, Zbigniew Jaegermann, and Małgorzata Grądzka-Dahlke. "Polyurethanes from the crystalline prepolymers resistant to abrasive wear." Polish Journal of Chemical Technology 16, no. 4 (December 1, 2014): 14–20. http://dx.doi.org/10.2478/pjct-2014-0063.

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Abstract The research aimed at the selection of polyurethanes synthesized from poly(tetramethylene ether) glycol (PTMEG), as well as from two different isocyanates 4,4′-methylenebis(cyclohexyl)isocyanate (HMDI) and 4.4′-methylenebis(phenyl isocyanate) (MDI) in order to obtain polyurethane with increased resistance to abrasive wear and degradation for bio-medical application. Polyurethanes were fabricated from crystalline prepolymers extended by water. The paper presents preliminary results on polyurethane surface wettability, friction coefficient for different couples of the co-working materials such as polyurethane-polyurethane, polyurethane-titanium alloy, polyurethane-alumina, in comparison to commonly used polyethylene-titanium alloy. Shear strength of polyurethane-alumina joint, as well as viscosity of prepolymers were also measured. The values of friction coefficient were compared to literature data on commercially available polyurethane with the trade name Pellethane. Polyurethanes obtained are characterized by low abrasive wear and low friction coefficient in couple with the titanium alloy, what makes them attractive as possible components of ceramic-polymer endoprosthesis joints.
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6

Nakajima-Kambe, T., Y. Shigeno-Akutsu, N. Nomura, F. Onuma, and T. Nakahara. "Microbial degradation of polyurethane, polyester polyurethanes and polyether polyurethanes." Applied Microbiology and Biotechnology 51, no. 2 (February 25, 1999): 134–40. http://dx.doi.org/10.1007/s002530051373.

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7

Ke, Ruoyi, Zhaowen Lin, Hongbo Zhang, and Shilin Zhou. "Research Progress in Intrinsic Self-healing Polyurethane Materials Based on Dynamic Reversible Non-covalent Bonds." Journal of Physics: Conference Series 2324, no. 1 (August 1, 2022): 012007. http://dx.doi.org/10.1088/1742-6596/2324/1/012007.

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Abstract Polyurethane (PU) is a polymer with great capabilities like high elasticity, low-temperature resistance, wear resistance, and corrosion resistance. However, it will inevitably be damaged in processing or long-term use, which will shorten the service life of the material and increase the potential safety hazards. The widespread use of polyurethanes has given researchers more motivation to make polyurethanes self-healing, thereby eliminating material damage and potential safety hazards to a certain extent. This paper mainly reviews the self-healing mechanism and the research progress of intrinsic self-healing polyurethanes based on dynamic reversible non-covalent bonds, including H-bonding, metal-ligand, π-π and host-guest interactions. This paper holds that the non-covalent self-healing polyurethane can repair cracks repeatedly without adding a repair agent by introducing the above non-covalent reversible bonds into the polyurethane with good mechanical properties. Various types of reversible bonds provide a variety of options for self-healing. In addition, through the research on the preparation, mechanical properties, and self-healing ability of various self-healing polyurethanes, this paper summarizes and analyzes the prospect and existing problems of self-healing polyurethanes. In the future, researchers should focus on solving the existing deficiencies. This paper looks forward to finding a better scheme to improve the performance of self-healing polyurethanes and preparing ideal self-healing polyurethane materials that appear in the public’s field of vision. This paper is written to provide help for the research of self-healing PU and accelerate the transformation of the world to green development.
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8

Domańska, Agata, Anna Boczkowska, Marta Izydorzak, Zbigniew Jaegermann, and Krzysztof Kurzydłowski. "Polyurethanes used in the endoprosthesis of joints." Polish Journal of Chemical Technology 12, no. 3 (January 1, 2010): 10–14. http://dx.doi.org/10.2478/v10026-010-0025-y.

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Polyurethanes used in the endoprosthesis of joints The aim of the studies presented in this paper was the selection of the polyurethanes synthesized from different substrates in order to obtain i) ceramic - biodegradable polymer composite and ii) polyurethane resistant to abrasive wear. The polyurethanes were obtained from the crystalline prepolymers extended by water, because it may have a beneficial effect on the toxicity of the material. The properties of PUs were investigated using infrared spectroscopy, thermogravimetry, differential scanning calorimetry and scanning electron microscopy. In all the tested polyurethanes the peak from the reactive -NCO groups was not observed, which indicates that all the substrates are fully reacted. Such polyurethanes are characterized by interesting properties with the perspective use as components of ceramic-polymer joints endoprosthesis. The designed endoprosthesis should fulfill at least three functions: load bearing function (ceramic core), fastening and stabilizing endoprosthesis to the bone (composite ceramics - biodegradable polymer) and tribologic function allowing mating with parts of the prosthesis (polyurethane layer resistant to abrasive wear).
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9

Gunatillake, Pathiraja A., Darren J. Martin, Gordon F. Meijs, Simon J. McCarthy, and Raju Adhikari. "Designing Biostable Polyurethane Elastomers for Biomedical Implants." Australian Journal of Chemistry 56, no. 6 (2003): 545. http://dx.doi.org/10.1071/ch02168.

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The chemical structure, synthesis, morphology, and properties of polyurethane elastomers are briefly discussed. The current understanding of the effect of chemical structure and the associated morphology on the stability of polyurethanes in the biological environments is reviewed. The degradation of conventional polyurethanes appears as surface or deep cracking, stiffening, and deterioration of mechanical properties, such as flex-fatigue resistance. Polyester and poly(tetramethylene oxide) based polyurethanes degrade by hydrolytic and oxidative degradation of ester and ether functional groups, respectively. The recent approaches to develop polyurethanes with improved long-term biostability are based on developing novel polyether, hydrocarbon, polycarbonate, and siloxane macrodiols to replace degradation-prone polyester and polyether macrodiols in polyurethane formulations. The new approaches are discussed with respect to synthesis, properties and biostability based on reported in vivo studies. Among the newly developed materials, siloxane-based polyurethanes have exhibited excellent biostability and are expected to find many applications in biomedical implants.
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10

Datta, J., and J. T. Haponiuk. "Influence of Glycols on the Glycolysis Process and the Structure and Properties of Polyurethane Elastomers." Journal of Elastomers & Plastics 43, no. 6 (September 2, 2011): 529–41. http://dx.doi.org/10.1177/0095244311413447.

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In this work, the influence of glycols on the glycolysis process and the properties of obtained polyurethanes were investigated. The glycolysates were produced via glycolysis of waste polyurethane foam in the reaction with one of the following glycols: 1,3-propanediol, 1,5-pentanediol, and 1,6-hexanediol.The reactions were carried out for different mass ratios of polyurethane wastes to glycolysis agent, i.e. 6:1, 8:1, and 10:1. Polyurethanes were synthesized from the obtained intermediates by a one-step method of mixing polymeric di-isocyanate and the glycolysis products with molecular masses ranging from 700 to 1000, while a polyol (Poles 55/20) was used as a chain elongation agent. The influence of glycolysates on tensile strength and elongation at break of polyurethanes was investigated using a Zwick universal tensile tester. Thermal decomposition of the obtained glycolysates and polyurethanes was investigated by thermogravimetry coupled with Fourier transform infrared spectroscopy. It has been found that of all used glycols, 1,6-hexanediol gives the best improvement in the thermal stability of polyurethanes during the glycolysis process. The mean hardness of polyurethanes decreases but rebound resilience increases with chain length of the glycol used for obtaining glycolysates.
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11

Desappan, Venkatesh, and Jaisankar Viswanathan. "Synthesis and Characterization of Biodegradable Jatropha Oil Based Polyurethanes Using Modified Sesame Oil as Cross-Linker Containing Different NCO Groups with Improved Thermal Stability." Asian Journal of Chemistry 31, no. 10 (August 30, 2019): 2375–82. http://dx.doi.org/10.14233/ajchem.2019.22014.

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In this work, the modified S-diol were prepared from sesame oil to produce polyol. The thermal responsive vegetable oil-based polyurethane was prepared by polycondensation method. The different diisocyanate react with jatropha-sesame oil polyol to produce higher density with molecular weight of polyurethanes structure and functionality were characterized by Fourier transform spectroscopy, proton nuclear resonance spectroscopy and gel permeation chromatography. The thermal analysis was carried with TG analysis. The kinetic and thermodynamic parameters was calculated by TGA decomposition temperature and compared with PU-1, PU-2 and PU-3. Furthermore, the corresponding decomposition temperature of polyurethanes activation energy were calculated by Coats-Redfern, Sharp-Wentworth and Freeman-Carols methods, and it is investigated with lifetime of polyurethanes. Depending on the physically observed NH and C=O linkages of polyurethane matrix, which enhancing the hard and soft segment to improve their chain mobility. The success of the investigated polyurethanes, the corresponding estimated enthalpy, entropy and pre-exponential factors are much closer with toluene and phenyl based polyurethane matrix
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12

Yeoh, Fang Hoong, Choy Sin Lee, Yew Beng Kang, Shew Fung Wong, Sit Foon Cheng, and Wei Seng Ng. "Production of Biodegradable Palm Oil-Based Polyurethane as Potential Biomaterial for Biomedical Applications." Polymers 12, no. 8 (August 17, 2020): 1842. http://dx.doi.org/10.3390/polym12081842.

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Being biodegradable and biocompatible are crucial characteristics for biomaterial used for medical and biomedical applications. Vegetable oil-based polyols are known to contribute both the biodegradability and biocompatibility of polyurethanes; however, petrochemical-based polyols were often incorporated to improve the thermal and mechanical properties of polyurethane. In this work, palm oil-based polyester polyol (PPP) derived from epoxidized palm olein and glutaric acid was reacted with isophorone diisocyanate to produce an aliphatic polyurethane, without the incorporation of any commercial petrochemical-based polyol. The effects of water content and isocyanate index were investigated. The polyurethanes produced consisted of > 90% porosity with interconnected micropores and macropores (37–1700 µm) and PU 1.0 possessed tensile strength and compression stress of 111 kPa and 64 kPa. The polyurethanes with comparable thermal stability, yet susceptible to enzymatic degradation with 7–59% of mass loss after 4 weeks of treatment. The polyurethanes demonstrated superior water uptake (up to 450%) and did not induce significant changes in pH of the medium. The chemical changes of the polyurethanes after enzymatic degradation were evaluated by FTIR and TGA analyses. The polyurethanes showed cell viability of 53.43% and 80.37% after 1 and 10 day(s) of cytotoxicity test; and cell adhesion and proliferation in cell adhesion test. The polyurethanes produced demonstrated its potential as biomaterial for soft tissue engineering applications.
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13

Xu, Chun Lei, Yi Hu, Jin Qiang Liu, Sheng Peng Wang, Shao Min Qu, and Jian Hua Xu. "The Preparation of Core-Shell Type Acrylic-Polyurethane Composite Emulsions for Pigment Printing." Advanced Materials Research 332-334 (September 2011): 387–90. http://dx.doi.org/10.4028/www.scientific.net/amr.332-334.387.

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Vinyl-endblocked polyurethanes were prepared from polyether diols(N210), isophorone diisocyanate (IPDI), dimethylol propionic acid (DMPA) and 2-hydroxyethyl acrylate (HEA). The core-shell structure acrylic-polyurethane composite emulsion was prepared by seeded emulsion polymerization of methyl methacrylate (MMA) and butyl acrylate (BA) using the polyurethanes emulsions as seeded emulsions. The core and shell regions were occupied by acrylic polymer and polyurethane, respectively. Because polyurethanes were vinyl-endblocked, acrylic monomers could graft partially to them. The formation of core-shell structure was observed by transmission electron microscopy (TEM). The structure and properties of dried film were studied by Fourier-transform infrared spectroscopy (FT-IR) and TGA.
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14

Zheng, Qin, Shuling Gong, Haiqing Dong, and Yuanyin Chen. "Calix[4]arenes Used as a New Type of Chain Extender in the Preparation of Polyurethanes." Australian Journal of Chemistry 60, no. 3 (2007): 167. http://dx.doi.org/10.1071/ch06387.

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A series of polyether– or polyester–polyurethanes based on tetrahydrofuran–propylene oxide copolyether diol (PTMG/PPG) or poly(ethylene terephthalate) diol (PET), toluene diisocyanate (TDI), and three kinds of chain extenders including two calix[4]arene derivatives and 3,3´-dichloro-4,4´-diaminodiphenylmethane (MOCA) were synthesized in toluene. The thermal stability and mechanical properties of solvent-type polyurethanes were investigated. Incorporation of calixarenes into polyurethane backbones improved the thermal properties of the polyurethane as a result of the residual phenol hydroxy groups of the calix[4]arene units. Compared with polyurethane chain-extended by MOCA, the polyurethanes with calix[4]arene derivatives had higher elongation at break, lower elastic modulus, and lower yield strength, as a result of the larger steric cubage of calix[4]arene units and relatively large free volume of the polymer.
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15

Ciastowicz, Żaneta, Renata Pamuła, and Andrzej Białowiec. "Utilization of Plant Oils for Sustainable Polyurethane Adhesives: A Review." Materials 17, no. 8 (April 10, 2024): 1738. http://dx.doi.org/10.3390/ma17081738.

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The utilization of plant oils as a renewable resource for the production of polyurethane adhesives presents a promising way to improve sustainability and reduce environmental impact. This review explores the potential of various vegetable oils, including waste oils, in the synthesis of polyurethanes as an alternative to conventional petroleum-based raw materials. The investigation highlights the environmental challenges associated with conventional polyurethane production and highlights the benefits of switching to bio-renewable oils. By examining the feasibility and potential applications of vegetable oil-based polyurethanes, this study emphasizes the importance of further research and development in this area to realize the full potential of sustainable polyurethane adhesives. Further research and development in this area are key to overcoming the challenges and realizing the full potential of plant-oil-based polyurethanes in various industrial applications.
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16

Echarri-Giacchi, María, and José Miguel Martín-Martínez. "Efficient Physical Mixing of Small Amounts of Nanosilica Dispersion and Waterborne Polyurethane by Using Mild Stirring Conditions." Polymers 14, no. 23 (November 25, 2022): 5136. http://dx.doi.org/10.3390/polym14235136.

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Good dispersion of nanosilica particles in waterborne polyurethane was obtained by mild mechanical stirring when 0.1–0.5 wt.% nanosilica in aqueous dispersion was added. The addition of small amounts of nanosilica produced more negative Z-potential values, increased the surface tension and decreased the Brookfield viscosity, as well as the extent of shear thinning of the waterborne polyurethane. Depending on the amount of nanosilica, the particle-size distributions of the waterborne polyurethanes changed differently and the addition of only 0.1 wt.% nanosilica noticeably increased the percentage of the particles of 298 nm in diameter. The DSC curves showed two melting peaks at 46 °C and 52 °C, as well as an increase in the melting enthalpy. In addition, when nanosilica was added, the crystallization peak of the waterborne polyurethane was displaced to a higher temperature and showed higher enthalpy. Furthermore, the addition of 0.1–0.5 wt.% nanosilica displaced the temperature of decomposition of the soft domains to higher temperatures due to the intercalation of the particles among the soft segments; this led to a change in the degree of phase separation of the waterborne polyurethanes. As a consequence, improved thermal stability and viscoelastic and mechanical properties of the waterborne polyurethanes were obtained. However, the addition of small amounts of nanosilica was detrimental for the wettability and adhesion of the waterborne polyurethanes due to the existence of acrylic moieties on the nanosilica particles, which seemed to migrate to the interface once the polyurethane was cross-linked. In fact, the final T-peel strength values of the joints made with the waterborne polyurethanes containing nanosilica were significantly lower than the one obtained with the waterborne polyurethane without nanosilica; the higher the nanosilica content, the lower the final adhesion. The better the nanosilica dispersion in the waterborne polyurethane+nanosilica, the higher the final T-peel strength value.
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17

Jayakumar, R., S. Nanjundan, and M. Prabaharan. "Developments in Metal‐Containing Polyurethanes, Co‐polyurethanes and Polyurethane Ionomers." Journal of Macromolecular Science, Part C: Polymer Reviews 45, no. 3 (July 2005): 231–61. http://dx.doi.org/10.1081/mc-200067721.

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18

Okieimen, F. E., I. O. Bakare, and C. Pavithran. "Network Structures, Flexibility and Stability in Thermal and Chemical Environments of Polyurethane Prepared from Rubber Seed Oil." Advanced Materials Research 62-64 (February 2009): 324–34. http://dx.doi.org/10.4028/www.scientific.net/amr.62-64.324.

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Rubber seed oil monoglyceride was prepared by glycerolysis and characterized by chemical and spectroscopic methods. The monoglyceride was reacted with excess diisocyanates (hexamethylene -diisocyanate and toluene diisocyanate), and the network structures and molecular mass of the polyurethane were determined from swelling experiments in toluene and size exclusion chromatography respectively. The polyurethane films obtained were characterized in terms of their resistance to chemicals (water, brine, dilute acid and alkali) thermal stability and tensile and flexural strength and modulus. It was found that under the experimental conditions, conversion of the triglyceride content of the rubber seed oil to monoglyceride not quantitative less than 70%. The measured properties of the RSO-based polyurethanes were attributed to the degree of crosslinking and the observed superior properties of the polyurethane obtained with hexamethylene diisocyanate in comparison with polyurethane obtained with toluene diisocyanate were explained in terms of structure-property relationship. The measured properties of RSO-based polyurethanes compare favourably with the properties reported for polyurethanes derived from other vegetable oils.
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19

Senthilkumar, Natarajan, and Mohammad Luqman. "Metal-Containing Polyurethanes: An Overview." Materials Science Forum 657 (July 2010): 1–25. http://dx.doi.org/10.4028/www.scientific.net/msf.657.1.

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The combination of the concept of metallopolymers with urethane chemistry offers a versatile approach for the synthesis of new polyurethane materials. Polyurethanes are a distinct class of materials with tremendous industrial importance, and it is of interest to develop these materials with modified thermal and liquid crystalline behavior for advanced applications. Generally, polyurethanes suffer a major disadvantage of poor thermal stability. This can be improved upon by chemical modification of their structures by the incorporation of thermally stable heterocyclic ring structures along with transition metals. Metal-containing polyurethanes prepared from a polymeric diol, diisocyanate and a metal containing diol (metallodiol and metallomesogenic diol) as a chain extender are attracting contemporary research interest. The addition of a polymeric diol (polyol) induces flexibility to the polyurethane by reducing the glass transition temperature, increases its solubility and imparts elastomeric properties. Multifunctional polymers are materials poised for applications in different avenues with preference for plastic electronics. An introduction-cum-overview of synthesis and applications of metal-containing polyurethanes is presented in this chapter.
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20

Tran, Tuan, Prasun Kumar, Hak-Ryul Kim, Ching Hou, and Beom Kim. "Microbial Conversion of Vegetable Oil to Hydroxy Fatty Acid and Its Application to Bio-Based Polyurethane Synthesis." Polymers 10, no. 8 (August 19, 2018): 927. http://dx.doi.org/10.3390/polym10080927.

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New polyurethanes were synthesized based on dihydroxy fatty acid obtained by the microbial conversion of olive oil. Monounsaturated 7,10-dihydroxy-8(E)-octadecenoic acid (DOD) was produced from olive oil by Pseudomonas aeruginosa PR3 and reacted with hexamethylene diisocyanate (HMDI) at different ratios to form polyurethanes. Fourier transform infrared spectroscopy and gas chromatography/mass spectrometry confirmed the synthesis of DOD. The thermal and tensile properties of the polyurethanes were investigated by differential scanning calorimetry, thermogravimetric analysis, and a universal testing machine. At an isocyanate/hydroxyl ratio of 1.4, the polyurethane exhibited an elongation at break of 59.2% and a high tensile strength of 37.9 MPa. DOD was also mixed with polycaprolactone diol or polyethylene glycol at different weight ratios and then reacted with HMDI to produce new polyurethanes of various properties. These polyurethanes displayed higher elongation at break and good thermal stability. This is the first report on the synthesis of polyurethanes based on DOD produced by the microbial conversion of vegetable oil.
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21

Alaa, M. A., Kamal Yusoh, and S. F. Hasany. "Comparative Study of Physico-Chemical Properties of Pure Polyurethane and Polyurethane Based on Castor Oil." Advanced Materials Research 983 (June 2014): 39–43. http://dx.doi.org/10.4028/www.scientific.net/amr.983.39.

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Petroleum based polyurethanes are contributing major portions in the world requirement. To overcome the environmental issues and price adaptability, there is always a massive demand of utilization of renewable resources for polyurethane synthesis with comparable physico-chemical properties. Castor oil is the only major natural vegetable oil that contains a hydroxyl group (-OH) and unsaturated double bonds (C=C) in its organic chain and therefore can be employed with or without modification due to the excellent properties derived from the hydrophobic nature of triglycerides. In this study, physico-chemical properties of high performance polyurethane synthesized from Poly propylene glycol (PPG) in comparison with a combination of PPG and Castor oil (a renewable source), by in situ polymerization technique has been studied. The variations in properties of both types of polyurethanes are evaluated by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Thermogravimetric analysis technique (TGA). Tensile strength properties were investigated by Film Tensile testing equipment. Results indicated the presence of large-CH stretching in castor oil mixed polyurethane with a larger oxidative thermal stability, over a pure PPG polyurethanes. Tensile properties were found almost comparable in pure and mixed polymers, which signify the usage of mixed polymer in coming future, to overcome the environmental and economical crisis in polyurethanes synthesis.
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22

Kim, Jang Soon, Ok Hyoung Lee, and Yun Soo Lim. "AFM Studies on the Effect of Crystalline Interphase on Adhesion of Polyurethane Thin Film to Al Substrate." Materials Science Forum 658 (July 2010): 65–68. http://dx.doi.org/10.4028/www.scientific.net/msf.658.65.

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Polyurethanes crystallized at the aluminum surface, but the crystalline interphase varied with polyol OH number. Early stage of spherulite formation was characterized using AFM after removing amorphous polyurethane. The crystallite shapes of polyurethanes were correlated with the bond strength measured from indentation debonding. Interestingly, the samples involving non-specific shape of crystallites displayed high bond strength, while the polyurethanes with rod-like crystallite poorly adhered to aluminum substrate. Although crystallite shape did not unequivocally relate to bond strength, the results propose that there is a probable correlation.
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23

Lin, Ling, Haiyan Mao, Ziyin Li, Wenyao Li, and Chaoxia Wang. "Preparation and Characterization of Optically Active Polyurethane from Rotatory Binaphthol Monomer and Polyurethane Prepolymer." Molecules 26, no. 10 (May 18, 2021): 2986. http://dx.doi.org/10.3390/molecules26102986.

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Optically active polymers are promising multifunctional materials with great application potentials. Herein, environmentally friendly optically active polyurethanes (OPUs) were obtained by introducing rotatory binaphthol monomer to polyurethane. The influence of binaphthol monomer content on the structure, mechanical properties, infrared emissivity, and thermal insulation of OPUs was studied intensively. Structure characterization indicated that the optically active polyurethanes have been successfully synthesized. The OPU synthesized with BIMOL and BDO at the mole ratio of 1:1 presented better thermal resistance. In addition, OPUs showed enhanced tensile strength and stretchability with the increase of BINOL content to a certain extent due to its rigid structural features and high molecular weight. The optically active polyurethanes showed lower infrared emissivity values (8–14 μm) than waterborne polyurethane (WPU), and the infrared emissivity decreased from 0.850 to 0.572 as the content of the BINOL monomer increased. Moreover, OPU4 exhibited the best heat insulation and cooling ability with about a 7 °C temperature difference. The thus-synthesized optically active polyurethanes provide an effective solution for developing highly effective thermal insulation materials.
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Zumbardo-Bacelis, Gualberto Antonio, Laura Peponi, Rossana Faride Vargas-Coronado, Eustolia Rodríguez-Velázquez, Manuel Alatorre-Meda, Pascale Chevallier, Francesco Copes, Diego Mantovani, Gustavo A. Abraham, and Juan Valerio Cauich-Rodríguez. "A Comparison of Three-Layer and Single-Layer Small Vascular Grafts Manufactured via the Roto-Evaporation Method." Polymers 16, no. 10 (May 8, 2024): 1314. http://dx.doi.org/10.3390/polym16101314.

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This study used the roto-evaporation technique to engineer a 6 mm three-layer polyurethane vascular graft (TVG) that mimics the architecture of human coronary artery native vessels. Two segmented polyurethanes were synthesized using lysine (SPUUK) and ascorbic acid (SPUAA), and the resulting materials were used to create the intima and adventitia layers, respectively. In contrast, the media layer of the TVG was composed of a commercially available polyurethane, Pearlbond 703 EXP. For comparison purposes, single-layer vascular grafts (SVGs) from individual polyurethanes and a polyurethane blend (MVG) were made and tested similarly and evaluated according to the ISO 7198 standard. The TVG exhibited the highest circumferential tensile strength and longitudinal forces compared to single-layer vascular grafts of lower thicknesses made from the same polyurethanes. The TVG also showed higher suture and burst strength values than native vessels. The TVG withstood up to 2087 ± 139 mmHg and exhibited a compliance of 0.15 ± 0.1%/100 mmHg, while SPUUK SVGs showed a compliance of 5.21 ± 1.29%/100 mmHg, akin to coronary arteries but superior to the saphenous vein. An indirect cytocompatibility test using the MDA-MB-231 cell line showed 90 to 100% viability for all polyurethanes, surpassing the minimum 70% threshold needed for biomaterials deemed cytocompatibility. Despite the non-cytotoxic nature of the polyurethane extracts when grown directly on the surface, they displayed poor fibroblast adhesion, except for SPUUK. All vascular grafts showed hemolysis values under the permissible limit of 5% and longer coagulation times.
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Sur, Suk-Hun, Pil-Jun Choi, Jae-Wang Ko, Jae-Yeon Lee, Young-Hee Lee, and Han-Do Kim. "Preparation and Properties of DMF-Based Polyurethanes for Wet-Type Polyurethane Artificial Leather." International Journal of Polymer Science 2018 (September 2, 2018): 1–9. http://dx.doi.org/10.1155/2018/7370852.

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DMF-based polyurethanes for wet-type polyurethane artificial leather were prepared using 4,4′-diphenylmethane diisocyanate (MDI) as diisocyanate, 1,4-butanediol (BD)/1,6-hexanediol (HD) as chain extender, and four different macroglycols (MW: 2000): poly(butylene/3-methyl-pentylene adipate) glycol based on 1,4-butanediol/3-methyl-1,5-pentanediol (MPD), poly(butylene adipate) glycol based on BD, polycarbonate glycol based on HD/MPD, and polycarbonate glycol based on HD. The properties of the as-polymerized polyurethane solutions and their films and the size/uniformity of cells of the foam layer of the resulting artificial leather were investigated. The viscosities of as-polymerized polyurethane solutions were significantly high in the range of 7500–15,000 cps, indicating that the molecular weight of the obtained polyurethanes is high. The tensile strengths of polyurethane films based on carbonate-polyol and BD chain extender were found to be higher than those of polyurethane films based on ester-polyol and HD chain extender. The elongation at the break of polyurethane films with the MPD component were higher than that of polyurethane films without the MPD component. The artificial leather containing MPD had smaller cells than the artificial leather without MPD and had higher uniformity. From these results, DMF-based polyurethanes prepared by using MPD components containing polyols are found to be most suitable for wet-type artificial leather.
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Song, Ru Yi, Yong Yan Li, Xin Ping Li, Jing Zhang, and Heng Quan. "Influences of Ion Abundance of Cationic Hydrophilic Polyurethane Modified with Polysiloxane on its Emulsion Properties." Advanced Materials Research 781-784 (September 2013): 2685–89. http://dx.doi.org/10.4028/www.scientific.net/amr.781-784.2685.

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Several cationic water-based polyurethanes end-capped with silicone coupling agent with different ion abundance are prepared. The effects of ion abundance of those polyurethanes on its emulsion particle size distribution, wet rubbing fastness improvement, hydrophility and soft handle are studied. The results show that the sample with moderate cationic ion abundance has optimal efficiency for color fixing of reactive dyes, and the quaterized cationic groups in polyurethane molecule should has positive contribution to hydrophility and soft handle of the treated fabric, especially for the color fabric treated with higher concentration polyurethane emulsion.
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Lee, Jong Baek, and Byung Won Kang. "Synthesis and Properties of Thermotropic Main-Chain Type Liquid Crystalline Polyurethanes Containing Biphenyl Mesogen." Key Engineering Materials 342-343 (July 2007): 729–32. http://dx.doi.org/10.4028/www.scientific.net/kem.342-343.729.

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A new type of thermotropic main-chain liquid crystalline polyurethanes containing biphenyl units was synthesized by polyaddition reaction of diisocyanates such as 2,6-tolylene diisocyanate, 2,5-tolylene diisocyanate, 2,4-tolylene diisocyanate, and 1,4-phenylene diisocyanate, with 4,4′-Bis(8-hydroxyoctoxy)biphenyl (BP8). The structure of the monomer and the corresponding polymers were confirmed using FT-IR and 1H-NMR spectroscopic methods. BP8 exhibited a smectic type mesophase, however, nematic phases were found for all synthesized liquid crystalline polyurethanes except for 1,4-phenylene diisocyanate/BP8 based polyurethane. For example, polyurethane 2,5-TDI/BP8 exhibited monotropic liquid crystallinity in the temperature ranging from 172 to 160 °C on the cooling stage. Properties of these polyurethanes were studied by differential scanning calorimetry (DSC), and optical polarizing microscopy. The FT-IR study indicated that the hydrogen bonding among urethane linkages attributed to the mesomorphism.
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Wang, Kun, Jiping Yang, Chen Gong, and Hao Lu. "Polyurethanes with aggregation-enhanced emission characteristics: preparation and properties." Faraday Discussions 196 (2017): 43–54. http://dx.doi.org/10.1039/c6fd00175k.

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An amino-terminated poly(propylene glycol)-modified tetraaryl-buta-1,3-diene derivative (TABDAA) was introduced to synthesize polyurethanes with different ratios of soft/hard segments. A mixture of TABDAA and poly(tetrahydrofuran) 1000 as the soft segments was reacted with 4,4-diphenylmethane diisocyanate and 1,4-butanediol as the hard segments in molar ratios of 1 : 2 : 1, 2 : 3 : 1, and 3 : 4 : 1 to give the desired polyurethanes named TMPU-211, TMPU-321 and TMPU-431, respectively. The three polyurethanes exhibited different aggregation-enhanced emission (AEE) behaviors because of their different soft/hard segment ratios. The polyurethanes with a higher soft segment content tended to form bigger particles in a DMF/water mixture solution, thus causing a sharper increase in their fluorescence intensity. In addition, the polyurethane films exhibited different fluorescence intensities after different heat treatments. After a quenching treatment of the soft segments in the polyurethane films, the fluorescence intensity dropped greatly. When these quenched polyurethane films were thermally annealed at 60 °C for 24 hours, their fluorescence intensity exceeded the initial intensity of the as-prepared films. Differential scanning calorimetry results showed that the polyurethane films in the quenched condition did not present the endothermal melting peak of the soft segments, and the melting peaks appeared again after thermal annealing. AFM experiments showed that an ordered arrangement was achieved after the heat treatment of these AEE polyurethane films. These results demonstrated that the polymer structure had a significant effect on the AEE properties of the polyurethane films, and more importantly, it is of great significance in improving the fluorescence emission of the AEE polymers and also for their potential application in fluorescent probes, stimuli-responsive materials, PLED devices and so on.
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Patel, Rasmika, Amin Hirani, and Hitesh Patel. "Flame Retardant Polyurethanes and their Applications for the Improvement in Properties of Conventional Castor Oil Based Polyurethane." Material Science Research India 11, no. 2 (December 10, 2014): 159–67. http://dx.doi.org/10.13005/msri/110209.

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The urethane polymers of castor oil (COPU) are used in many commercial applications but one of the major limitations of these polymers is their inherent flammability and poor mechanical properties. Polymers containing phosphorous groups belong to the fire retardants, and when blended with castor oil based polyurethane improves the latter’s fire retardant properties. Present work, deals with the synthesis of a monomer bis (m-hydroxy phenyl) phenyl phosphate (BHPPP) and its related polyurethanes. Characterization of the monomer and polyurethanes are discussed. Blending of the polyurethanes with COPU in different proportions improves both the flame retardant and mechanical properties of the COPU.
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Brzeska, Joanna, Agnieszka Tercjak, Wanda Sikorska, Marek Kowalczuk, and Maria Rutkowska. "Morphology and Physicochemical Properties of Branched Polyurethane/Biopolymer Blends." Polymers 12, no. 1 (December 19, 2019): 16. http://dx.doi.org/10.3390/polym12010016.

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The aim of this study is the analyze the structure of branched polyurethanes based on synthetic poly([R,S]-3-hydroxybutyrate) and their blends with biopolymers and montmorillonite. The properties which would predict the potential susceptibility of these materials to degradation are also estimated. Fourier-transform infrared spectroscopy with attenuated total reflection analysis shows that poly([d,l]-lactide) is on the surfaces of polyurethanes, whereas chitosan and starch are included inside the blend network. Atomic force microscopy images have shown that the surfaces of investigated samples are heterogenous with the formation of spherulites in case of pure polyurethanes. The presence of biopolymers in the blend reduced the crystallinity of polyurethanes. Thermal stability of blends of polyurethanes with poly([d,l]-lactide) and polysaccharides decreased in comparison to pure polyurethanes. Although the tensile strength is reduced after the blending of polyurethanes with biopolymers, the elongation at break increased, especially in the case of polyurethane/poly([d,l]-lactide) blends. The presence of polysaccharides in the obtained blends caused the significant reduction of contact angle after one minute from water drop immersion. This hydrophilizing effect is the highest when montmorillonite has been incorporated into the chitosan blend. The estimated properties of the obtained materials suggest their potential sensitivity on environmental conditions.
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Pavlicevic, Jelena, Mirjana Jovicic, Vesna Simendic, Oskar Bera, Radmila Radicevic, and Milena Spírková. "Modification of epoxy resins with thermoplastic segmented polycarbonate-based polyurethanes." Chemical Industry 68, no. 6 (2014): 755–65. http://dx.doi.org/10.2298/hemind130904086p.

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In this work, epoxy hybrid materials were synthesized by addition of thermoplastic segmented aliphatic polyurethanes with good elastic properties. The modified epoxy samples were obtained by curing of previously homogenized mixture of prepared polyurethane melts, epoxy resin and crosslinking agent Jeffamine D-2000. The influence of different weight content of polyurethanes (5, 10 and 15 wt. % compared to pure epoxy resin) as well the influence of different hard segments of elastomers (20, 25 and 30 wt. %) on the curing of modified epoxy systems was studied. The curing was followed by differential scanning calorimetry (DSC), in dynamic regime from 30 to 300?C, at three heating rates (5, 10 and 20?C/min). With the increase of hard segments content of polyurethanes added in higher concentration (10 and 15 wt. %) into epoxy matrix, the temperature of maximum ratio of curing was shifted to lower values (from 205 to 179?C). Obtained DSC data were analyzed using two integral methods (Ozawa-Flynn-Wall and Kissinger-Akahira-Sunose) and one differential kinetic model (Friedman). The significant differences were observed in the second part of the epoxy curing (for the reaction degrees higher than 60 %), where the values of activation energies remarkably increase. The addition of polyurethane elastomers retarded the curing process due to decreased mobility of reactant molecules caused by higher viscosity of reaction mixture. By detailed analysis of determined kinetic parameters, it is concluded that the influence of slow diffusion is more pronounced in the presence of thermoplastic polycarbonate-based polyurethanes, which confirmed their effect on the mechanism of epoxy curing. The highest tensile strength and hardness showed the DGEBA modified with the polyurethane with highest hard segment content. Increasing the hard segment content of polyurethane and its concentration in matrix, the tensile strength of modified epoxy was increased. The elongation at break of modified epoxy samples was significantly improved by addition of polycarbonate-based polyurethanes with low hard segment content, due to higher content of flexible soft segment chains.
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Kaur, Raminder, Pooja Singh, Surya Tanwar, Gunjan Varshney, and Sarla Yadav. "Assessment of Bio-Based Polyurethanes: Perspective on Applications and Bio-Degradation." Macromol 2, no. 3 (July 4, 2022): 284–314. http://dx.doi.org/10.3390/macromol2030019.

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Among numerous synthetic macromolecules, polyurethane in its different forms has proven its sheer dominance and established a reputation as a reliable and trusted material due to its proficiency in terms of superior properties, which include: high mechanical strength and abrasion resistance, good durability, good adhesion, good thermal stability, excellent chemical and weathering resistance. Synthetic polyurethane materials are non-biodegradable, poisonous, and use petrochemical-based raw materials, which are now depleting, leading to a surge in polyurethane production costs. Bio-based polyurethanes (PU) have been synthesized by researchers in recent decades and have mostly overtaken petrochemical-based PU in terms of challenges such as solid pollution, economic effectiveness, and availability of raw materials. Enormous kinds of available bio-renewable sources as predecessors for the production of polyols and isocyanates have been explored for the development of “greener” PU materials; these bio-based polyurethanes have significant potential to be used as future PU products, with a partial or total replacement of petroleum-based polyurethanes, due to increasing concern about the environment, their relatively low cost and biodegradability. This critical review concentrates on the possibilities of renewable sources to be used for polyurethane production and gives a clear perspective on the journey, utilization, and recent advancements in the field of different bio-based polyurethane polymers that have arisen over the last decade.
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Oprea, Stefan, Violeta Otilia Potolinca, and Veronica Oprea. "Physical properties and the ability to disperse into different polar solvents of the new polyurethane–cellulose composites." Journal of Elastomers & Plastics 52, no. 6 (September 24, 2019): 548–72. http://dx.doi.org/10.1177/0095244319877562.

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Novel castor oil (CO)-based polyurethane composites which include polyethylene glycol (PEG) as a polyol and cellulose fillers were prepared. The purpose of this article was to render polyurethane composites that can be dispersed in polar solvents (ethyl alcohol, isopropyl alcohol, and water) using bio-based feedstocks such as CO and cellulose. The chemical structures of the polyurethanes and their cellulose composites were studied by Fourier transform infrared spectroscopy and nuclear magnetic resonance of protons. The atomic force microscopy results showed the surface topography of the cellulose–polyurethane composites matrix. The inclusion of cellulose has been found to improve the thermal stability of the materials and their ability to disperse into the studied polar solvents. Cellulose along with PEG plays an important role in increasing the degree of moisture within the polyurethane composite matrix. Thus, we obtained solutions in polar solvents of polyurethane–cellulose composites without the use of waterborne polyurethanes.
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Kemona, Aleksandra, and Małgorzata Piotrowska. "Polyurethane Recycling and Disposal: Methods and Prospects." Polymers 12, no. 8 (August 5, 2020): 1752. http://dx.doi.org/10.3390/polym12081752.

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Growing water and land pollution, the possibility of exhaustion of raw materials and resistance of plastics to physical and chemical factors results in increasing importance of synthetic polymers waste recycling, recovery and environmentally friendly ways of disposal. Polyurethanes (PU) are a family of versatile synthetic polymers with highly diverse applications. They are class of polymers derived from the condensation of polyisocyanates and polyalcohols. This paper reports the latest developments in the field of polyurethane disposal, recycling and recovery. Various methods tested and applied in recent years have proven that the processing of PU waste can be economically and ecologically beneficial. At the moment mechanical recycling and glycolysis are the most important ones. Polyurethanes’ biological degradation is highly promising for both post-consumer and postproduction waste. It can also be applied in bioremediation of water and soil contaminated with polyurethanes. Another possibility for biological methods is the synthesis of PU materials sensitive to biological degradation. In conclusion, a high diversity of polyurethane waste types and derivation results in demand for a wide range of methods of processing. Furthermore, already existing ones appear to be enough to state that the elimination of not reprocessed polyurethane waste in the future is possible.
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Briz-López, Eva Marina, Rodrigo Navarro, Héctor Martínez-Hernández, Lucía Téllez-Jurado, and Ángel Marcos-Fernández. "Design and Synthesis of Bio-Inspired Polyurethane Films with High Performance." Polymers 12, no. 11 (November 17, 2020): 2727. http://dx.doi.org/10.3390/polym12112727.

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In the present work, the synthesis of segmented polyurethanes functionalized with catechol moieties within the hard or the soft segment is presented. For this purpose, a synthetic route of a new catechol diol was designed. The direct insertion of this catechol-free derivative into the rigid phase led to segmented polyurethanes with low performance (σmax ≈ 4.5 MPa). Nevertheless, when the derivative was formally located within the soft segment, the mechanical properties of the corresponding functionalized polyurethane improved considerably (σmax ≈ 16.3 MPa), owing to a significant increase in the degree of polymerization. It is proposed that this difference in reactivity could probably be attributed to a hampering effect of this catecholic ring during the polyaddition reaction. To corroborate this hypothesis, a protection of the aromatic ring was carried out, blocking the hampering effect and avoiding secondary reactions. The polyurethane bearing the protected catechol showed the highest molecular weight and the highest stress at break described to date (σmax ≈ 66.1 MPa) for these kind of catechol-functionalized polyurethanes. Therefore, this new approach allows for the obtention of high-performance polyurethane films and can be applied in different sectors, benefiting from the molecular adhesion introduced by the catechol ring.
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Yakushin, Vladimir, Uldis Stirna, Irina Sevastyanova, Dzintra Vilsone, Viesturs Zeltins, and Mikelis Kirpluks. "Properties of Polyurethanes Based on Tall Oil Fatty Acids Ester with Different Types of Flame Retardants." Key Engineering Materials 559 (June 2013): 115–20. http://dx.doi.org/10.4028/www.scientific.net/kem.559.115.

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To decrease the combustibility of polyurethanes based on tall oil fatty acids ester, additives of five different halogen- and phosphorus-containing flame retardants were used. The efficiency of the flame retardants was evaluated from the change in the thermal, mechanical and combustibility characteristics of the obtained polyurethanes. It has been found that the phosphorus-containing flame retardant Levagard 4090 N decreases the combustibility of polyurethane to the greatest extent.
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Rubio Hernández-Sampelayo, Alejandra, Rodrigo Navarro, Dulce María González-García, Luis García-Fernández, Rosa Ana Ramírez-Jiménez, María Rosa Aguilar, and Ángel Marcos-Fernández. "Biodegradable and Biocompatible Thermoplastic Poly(Ester-Urethane)s Based on Poly(ε-Caprolactone) and Novel 1,3-Propanediol Bis(4-Isocyanatobenzoate) Diisocyanate: Synthesis and Characterization." Polymers 14, no. 7 (March 23, 2022): 1288. http://dx.doi.org/10.3390/polym14071288.

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A series of non-toxic biodegradable and biocompatible polyurethanes bearing p-aminobenzoate moieties are presented. The introduction of this attractive motif was carried out by the synthesis of a novel isocyanate. These biodegradable polymers were chemically and physically characterized by several techniques and methods including bioassay and water uptake measurements. The molecular weight of the soft segment (poly-ε-caprolactone, PCL) and hard segment crystallinity dictated the mechanical behavior and water uptake. The behavior of short PCL-based polyurethanes was elastomeric, whilst increasing the molecular weight of the soft segment led to plastic polyurethanes. Water uptake was hindered for long PCL due to the crystallization of the soft segment within the polyurethane matrix. Furthermore, two different types of chain extender, hydrolyzable and non-hydrolyzable, were also evaluated: polyurethanes based on hydrolyzable chain extenders reached higher molecular weights, thus leading to a better performance than their unhydrolyzable counterparts. The good cell adhesion and cytotoxicity results demonstrated the cell viability of human osteoblasts on the surfaces of these non-toxic biodegradable polyurethanes.
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Lee, Jong Baek, Kwang Hyun Lee, Byung Chul Kang, Byung Won Kang, Sang Ll Lee, and Jin Kyung Lee. "Thermal Properties of a Liquid-Crystalline Polyurethanes Containing Biphenyl Mesogen." Key Engineering Materials 321-323 (October 2006): 1385–88. http://dx.doi.org/10.4028/www.scientific.net/kem.321-323.1385.

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A new type of thermotropic main-chain liquid crystalline polyurethanes containing biphenyl units was synthesized by polyaddition reaction of diisocyanates such as 2,6-tolylene diisocyanate, 2,5-tolylene diisocyanate, 2,4-tolylene diisocyanate, and 1,4-phenylene diisocyanate, with 4,4′-Bis(11-hydroxyundeyloxy)biphenyl (BP11). The structure of the monomer and the corresponding polymers were confirmed FT-IR and 1H NMR spectroscopic methods. BP11 exhibited a smectic type mesophase, however, nematic phase was found for all synthesized liquid crystalline polyurethanes except for 1,4-phenylene diisocyanate/BP11 based polyurethane. For example, polyurethane 2,5-TDI/BP11 exhibited monotropic liquid crystallinity in the temperature ranges from 173 to 156 °C on the cooling stage.
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Morales-González, Maria, Luis Eduardo Díaz, Carlos Dominguez-Paz, and Manuel F. Valero. "Insights into the Design of Polyurethane Dressings Suitable for the Stages of Skin Wound-Healing: A Systematic Review." Polymers 14, no. 15 (July 24, 2022): 2990. http://dx.doi.org/10.3390/polym14152990.

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Dressings made with polyurethanes have been found to exhibit good and varied biological properties that make them good candidates for this application. However, as has been seen, the wound-healing process is complex, which includes four different stages. So far, the design and evaluation of polyurethane for wound dressing has focused on achieving good properties (mechanical, physicochemical, and biological), but each of them separates from the others or even directed at only one of the stages of skin wound-healing. Therefore, the aim of this systematic review is to explore the applications of polyurethanes in wound dressings and to determine whether could be designed to cover more than one stage of skin wound-healing. The PRISMA guidelines were followed. The current research in this field does not consider each stage separately, and the design of polyurethane dressings is focused on covering all the stages of wound healing with a single material but is necessary to replace polyurethanes in short periods of time. Additionally, little emphasis is placed on the hemostasis stage and further characterization of polyurethanes is still needed to correlate mechanical and physicochemical properties with biological properties at each stage of the wound-healing. Current research demonstrates an effort to characterize the materials physiochemically and mechanically, but in terms of their biological properties, most of the literature is based on the performance of histological tests of explants morphologically probing the compromised tissues, which give an indication of the potential use of polyurethanes in the generation of wound-healing dressings.
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Lee, Dae-Woo, Han-Na Kim, and Dai-Soo Lee. "Introduction of Reversible Urethane Bonds Based on Vanillyl Alcohol for Efficient Self-Healing of Polyurethane Elastomers." Molecules 24, no. 12 (June 12, 2019): 2201. http://dx.doi.org/10.3390/molecules24122201.

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Urethane groups formed by reacting phenolic hydroxyl groups with isocyanates are known to be reversible at high temperatures. To investigate the intrinsic self-healing of polyurethane via a reversible urethane group, we synthesized vanillyl alcohol (VA)-based polyurethanes. The phenolic hydroxyl group of vanillyl alcohol allows the introduction of a reversible urethane group into the polyurethane backbone. Particularly, we investigated the effects of varying the concentration of reversible urethane groups on the self-healing of the polyurethane, and we proposed a method that improved the mobility of the molecules contributing to the self-healing process. The concentration of reversible urethane groups in the polyurethanes was controlled by varying the vanillyl alcohol content. Increasing the concentration of the reversible urethane group worsened the self-healing property by increasing hydrogen bonding and microphase separation, which consequently decreased the molecular mobility. On the other hand, after formulating a modified chain extender (m-CE), hydrogen bonding and microphase separation decreased, and the mobility (and hence the self-healing efficiency) of the molecules improved. In VA40-10 (40% VA; 10% m-CE) heated to 140 °C, the self-healing efficiency reached 96.5% after 30 min, a 139% improvement over the control polyurethane elastomer (PU). We conclude that the self-healing and mechanical properties of polyurethanes might be tailored for applications by adjusting the vanillyl alcohol content and modifying the chain extender.
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Liu, Beibei, Kun Wang, Hao Lu, Mingming Huang, Zhigang Shen, and Jiping Yang. "Thermally responsive AIE-active polyurethanes based on a tetraaniline derivative." RSC Advances 10, no. 68 (2020): 41424–29. http://dx.doi.org/10.1039/d0ra06193j.

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Hou, Jinghui, Yifei Ma, Zihan Zhang, Xuanhe Yang, Muhua Huang, and Chunpeng Chai. "The Relationship between Solid Content and Particle Size Ratio of Waterborne Polyurethane." Coatings 9, no. 6 (June 21, 2019): 401. http://dx.doi.org/10.3390/coatings9060401.

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A series of high solid content carboxylic acid/sulfonic acid waterborne polyurethanes was prepared by the emulsion dispersion method. The particle size and solid content were measured. By changing the particle size of the large particles to achieve different particle size ratios, high solid content waterborne polyurethanes were obtained at specific particle size ratios. When the particle size ratio was >7, 4–5 or 2–3, the aqueous polyurethane could reach a higher solid content (more than 56%). This indicated that solid content is related to particle size distribution in high solid content waterborne polyurethane. Moreover, the corresponding three-dimensional stacked models (simple cubic accumulation, face-centered cubic accumulation, cubic close packing and hexagonal closest packing) were established.
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Brzeska, Joanna, Agnieszka Tercjak, Wanda Sikorska, Marek Kowalczuk, and Maria Rutkowska. "Predicted Studies of Branched and Cross-Linked Polyurethanes Based on Polyhydroxybutyrate with Polycaprolactone Triol in Soft Segments." Polymers 12, no. 5 (May 7, 2020): 1068. http://dx.doi.org/10.3390/polym12051068.

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The number of cross-links in the non-linear polyurethane structure is the basic factor affecting its properties. Selected properties of aliphatic polyurethanes with soft segments made of different amounts of polycaprolactonetriol, polycaprolactonediol and synthetic, telechelic poly([R,S]-3-hydroxybutyrate) were determined. On the basis of changes in polyurethane properties, the correlation between these properties and the construction of soft segments was found. The structure of polyurethanes, their morphology, hydrophilicity, thermal and mechanical properties were examined. These properties were changed linearly up to 15% content of polycaprolactonetriol in soft segments. A further increase in the amount of triol causes that these properties are mainly determined by the high number of cross-links.
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Li, Ying, Sichong Chen, Jun Shen, Siqi Zhang, Ming Liu, Ruixue Lv, and Wang Xu. "Preparation and Properties of Biobased, Cationic, Waterborne Polyurethanes Dispersions from Castor Oil and Poly (Caprolactone) Diol." Applied Sciences 11, no. 11 (May 23, 2021): 4784. http://dx.doi.org/10.3390/app11114784.

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Biobased cationic waterborne polyurethanes (WPUs) were prepared using isophorone diisocyanate (IPDI), N-methyl diethanolamine (N-MDEA), polycaprolactone (PCL) diol, hydrochlotic acid (HCl), and 1,4-butanediol (BDO). To improve the mechanical performance and adhesive strength of the waterborne polyurethane films, different amounts of castor oil (CO) acting as a cross-linking agent were incorporated in the polyurethane structure. The structures of the waterborne polyurethanes were assessed by Fourier-transform infrared spectroscopy (FTIR). The combination of CO had a positive effect on the dispersion and stability properties of WPUs. WPUs containing higher content of CO demonstrated a remarkable enhancement in homogeneity among particles. The stable aqueous dispersion was obtained even when N-MDEA loading was as low as 3.2 wt%; a bonus of this low hydrophilic moiety was the excellent adhesive strength, whose T-peel strength could reach up to 36.8 N/25 mm, about 114% higher than that of WPU (17.2 N/25 mm) without any CO content. The elongation at break of CO7.40%-WPU was 391%. In addition, the fracture mechanism of the waterborne polyurethane films transformed from the brittle failure to the ductile fracture. The experiment results showed the CO-modified WPUs displayed excellent film-forming property, flexibility, and adhesion, which can be employed for constructing the eco-friendly, biodegradable, cationic, waterborne polyurethanes.
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Zahedifar, Pegah, Lukasz Pazdur, Christophe M. L. Vande Velde, and Pieter Billen. "Multistage Chemical Recycling of Polyurethanes and Dicarbamates: A Glycolysis–Hydrolysis Demonstration." Sustainability 13, no. 6 (March 23, 2021): 3583. http://dx.doi.org/10.3390/su13063583.

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The use of polyurethanes and, therefore, the quantity of its scrap are increasing. Considering the thermoset characteristic of most polyurethanes, the most circular recycling method is by means of chemical depolymerization, for which glycolysis is finding its way into the industry. The main goal of polyurethane glycolysis is to recover the polyols used, but only limited attempts were made toward recovering the aromatic dicarbamate residues and derivates from the used isocyanates. By the split-phase glycolysis method, the recovered polyols form a top-layer phase and the bottom layer contain transreacted carbamates, excess glycol, amines, urea, and other side products. The hydrolysis of carbamates results in amines and CO2 as the main products. Consequently, the carbamates in the bottom layer of polyurethane split-phase glycolysis can also be hydrolyzed in a separate process, generating amines, which can serve as feedstock for isocyanate production to complete the polyurethane material cycle. In this paper, the full recycling of polyurethanes is reviewed and experimentally studied. As a matter of demonstration, combined glycolysis and hydrolysis led to an amine production yield of about 30% for model systems. With this result, we show the high potential for further research by future optimization of reaction conditions and catalysis.
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46

Sitanggang, Vera Junita, Nyoman Jaya Wistara, and Philippe Gérardin. "Synthesis and Characterization of Poly(hydroxy)urethane from Polyols for Beech (Fagus sylvatica) Wood Impregnation." Jurnal Sylva Lestari 11, no. 2 (May 14, 2023): 218–35. http://dx.doi.org/10.23960/jsl.v11i2.701.

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A non-isocyanate route of polyurethane synthesis based on polyol (xylitol, sorbitol, glycerol, and PG3), alkyl carbonate (DMC and DEC), and diamine (HMDA, EDA, and DETA) was conducted for wood impregnation through in-site polymerization. The structure and mass average molecular weight (Mw) of the polyurethanes were analyzed using FTIR, NMR, and SEC. According to the results, polyurethane synthesis by a two-pot method in water brought cyclic carbonate degradation. The distribution of Mw of the polyurethanes showed that the most satisfying polymer (4380 g/mol) was prepared without solvent. Polyurethanes synthesized in methanol have a higher Mw than that in distilled water. In the same solvent, the use of HMDA resulted in a polymer with higher Mw than that of EDA. One-step wood impregnation in a solvent gave unsatisfactory WPG (12.59–19.71%) and LC (50.36–62.80%). However, one-step impregnation without solvent gave a higher WPG (78.39–87.63%) and a lower LC (19.11–21.25%). It is not feasible to be applied industrially. The two-step impregnation gave WPG (14.89-30.73%) and LC (42.22–56.52%). Wood impregnation using methanol or ethanol as the solvent was more recommended than using an aqueous solution. However, the resistance against leaching needs improvement. Keywords: Alkyl carbonate, diamine, polyol, polyurethane, wood impregnation
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47

Kordován, Marcell Árpád, Csaba Hegedűs, Katalin Czifrák, Csilla Lakatos, Ibolya Kálmán-Szabó, Lajos Daróczi, Miklós Zsuga, and Sándor Kéki. "Novel Polyurethane Scaffolds Containing Sucrose Crosslinker for Dental Application." International Journal of Molecular Sciences 23, no. 14 (July 18, 2022): 7904. http://dx.doi.org/10.3390/ijms23147904.

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In this paper, the synthesis, characterization, and properties of crosslinked poly(ε-caprolactone)-based polyurethanes as potential tissue replacement materials are reported. The polyurethane prepolymers were prepared from poly(ε-caprolactone)diol (PCD), polyethylene glycol (PEG)/polylactic acid diol (PLAD), and 1,6-hexamethylene diisocyanate (HDI). In these segmented polyurethanes, the role of PEG/PLAD was to tune the hydrophobic/hydrophilic character of the resulting polymer while sucrose served as a crosslinking agent. PLAD was synthesized by the polycondensation reaction of D,L-lactic acid and investigated by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and nuclear magnetic resonance spectroscopy (NMR). The crosslinked polyurethane samples (SUPURs) obtained were characterized by attenuated total reflectance Fourier-transform infrared spectroscopy (AT-FT-IR), swelling, and mechanical (uniaxial tensile tests) experiments. The thermo and thermomechanical behavior were studied by differential scanning calorimetry (DSC) and dynamical mechanical analysis (DMA). The viability of dental pulp stem cells was investigated in the case of polyurethanes composed of fully biocompatible elements. In our studies, none of our polymers showed toxicity to stem cells (DPSCs).
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48

Chalid, Mochamad, Hans J. Heeres, and Antonius A. Broekhuis. "A Study on the Structure of Novel Polyurethanes Derived from γ-Valerolactone-Based Diol Precursors." Advanced Materials Research 789 (September 2013): 274–78. http://dx.doi.org/10.4028/www.scientific.net/amr.789.274.

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As versatile biomass-based diol precursors, N,N'-1,2-ethanediylbis-(4-hydroxy-pentanamide) (1) and 4-hydroxy-N-(2-hydroxyethyl)-pentanamide (2) are potential monomers to synthesize novel polyurethanes through adding di-isocyanates. This study reported the structural analysis and molecular behavior of polyurethanes obtained from polymerization of the diol precursors with aliphatic and aromatic di-isocyanates (hexamethylene diisocyanate, HDI (3), and phenyl-diisocyanate, PDI (4)) in (N,N-dimethylacetamide (DMA) solvents with triethylamine (TEA) catalysts.1H-NMR,13C-NMR and Elemental Analysis confirmed structure of the polyurethanes built from both diols and di-isocyanates and FTIR indicated interaction among polyurethane molecules showed at lower wave numbers such as 2855-2976 cm-1for hydrogen-bonded NH groups and 1621-1643 cm-1for hydrogen-bonded C=O groups. Furthermore a study on influence of the inter-and intra-molecular hydrogen bonding on the thermal and mechanical properties of the polyurethanes would be an interesting investigation for the next study.
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49

Arévalo, Fabián R., Sonia A. Osorio, Nathaly A. Valcárcel, Jeimmy C. Ibarra, and Manuel F. Valero. "Characterization and in vitro Biocompatibility of Binary Mixtures of Chitosan and Polyurethanes Synthesized from Chemically Modified Castor Oil, as Materials for Medical Use." Polymers from Renewable Resources 9, no. 1 (February 2018): 23–38. http://dx.doi.org/10.1177/204124791800900102.

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This study aimed to evaluate the effect of the incorporation of chitosan into polyurethane matrices synthesized from chemically modified castor (Ricinus communis) oil by transesterification with pentaerythritol. An additional aim of this study was to determine the degree of acceptance as a biomaterial (obtained from renewable sources), based on the analysis of its mechanical properties (stress/rupture strain), hydrophilic character (contact angle), morphology (SEM) and in vitro compatibility of polyurethanes when in contact with mouse fibroblast L929 cells. No significant changes in mechanical properties were observed with the addition of chitosan to polyurethanes synthesized from chemically modified castor oil. All polyurethane formulas showed morphological changes with increased chitosan concentration. As chitosan/polyurethane binary mixtures do not present a cytotoxicity risk for L929 mouse fibroblasts and possess similar mechanical properties to soft and cardiovascular tissues, their use as a biomedical material is suggested.
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50

Sajkiewicz, P., J. Brzeska, P. Denis, W. Sikorska, M. Kowalczuk, and M. Rutkowska. "The preliminary studies of a structure and electrospinning of new polyurethanes based on synthetic atactic poly[(R, S)-3-hydroxybutyrate]." Bulletin of the Polish Academy of Sciences: Technical Sciences 62, no. 1 (March 1, 2014): 55–60. http://dx.doi.org/10.2478/bpasts-2014-0006.

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Abstract Novel polyurethanes based on synthetic, atactic poly[(R, S)-3-hydroxybutyrate] (a-PHB) and polycaprolactone (PCL) or polyoxytetramethylene (PTMG) diols were synthesized. It was shown that the presence of a-PHB within soft segments reduces crystallinity of PUR. Because of the low melting temperature for polyurethanes with PCL in soft segments, at this stage of work, electrospinning was limited to polyurethanes containing PTMG and a-PHB. Polyurethane containing 80% of PTMG and 20% of a-PHB was electrospun at various parameters from hexafluoro-2-propanole solution, resulting in formation of fibers with the average diameter ca. 2 μm. The fiber diameter decreased with decreasing polymer concentration in a solution and was practically insensitive to the needle-collector distance in the applied range of distances.
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