Synthesis and properties of polyester based polyurethanes
TL;DR: In this article, hydroxyl terminated polyesters were prepared by a melt condensation technique using adipic acid and various diols and diamines, and the glass transition temperature of the polymers were found to be in the region −25 to −55.
About: This article is published in European Polymer Journal.The article was published on 1982-01-01. It has received 5 citations till now. The article focuses on the topics: Isocyanate & Polyester.
Citations
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TL;DR: In this article, the effect of increasing NCO/OH molar ratio on the physico-mechanical and thermal properties of isocyanate terminated polyurethane prepolymer was investigated.
Abstract: The study investigates the effect of increasing NCO/OH molar ratio on the physico-mechanical and thermal properties of isocyanate terminated polyurethane prepolymer. The prepolymer was prepared using methylene diphenyl diisocyanate and difunctional polypropylene glycol. The NCO/OH molar ratio has been varied from 1.2:1 to 3:1. The formation of the prepolymer was confirmed by FTIR spectroscopy. The results reveal that the viscosity, weight average molecular weight and curing time of the prepolymer decreased with increase in NCO/OH molar ratio. When NCO/OH molar ratio increased, the tensile strength of the polyurethane film increased, while percent elongation decreased due to increase in hard segment content. The glass transition temperature of the prepolymer decreased with increase in NCO/ OH molar ratio of the prepolymer. Keywords : Polyurethane Prepolymer, Viscosity, Molecular Weight, Curing Time, Glass Transition Temperature.
20 citations
TL;DR: In this article, a rigid biodegradable polyester-based polyurethane was synthesized by reacting excess of isocyanate with poly(e-caprolactone)diol to obtain prepolymer which was then reacted with chain extender.
Abstract: The aim of this research work is to prepare biodegradable polyurethane composites and study their physical, mechanical, thermal, and biodegradation properties. Rigid biodegradable polyester-based polyurethane was synthesized by reacting excess of isocyanate with poly(e-caprolactone)diol to obtain prepolymer which was then reacted with chain extender. The polyurethane composites are prepared with nanoclay and titanium(IV)oxide nanopowder in different concentrations, and polyurethane containing 2% w/w of nanopowder had shown better properties. Biodegradation studies showed that the developed polyurethane materials when used as shoe soles will retain their strength while storage and use, but will decompose only after disposal into the environment.
12 citations
TL;DR: In this paper, the effect of different soft segment length on influencing the structure prop erty relationship of polyurethane prepolymer was studied, where the soft segment lengths were varied by using poly (propylene oxide) glycol and also by blending two polyols having similar chemical composition but of different molecular weight.
Abstract: Isocyanate terminated polyurethane prepolymer, a ba se material for water curable polyurethane bandage was prepared from diphenylmethane diisocyanate and poly (propylene ox ide) glycol. In polyurethanes, the diisocyanate ac t as hard segment and provides dimensional stability, whereas the polyol which forms the soft segment gives elastomeric char acter. Due to its segmented structure, polyurethane’s with a wide range of phys ico-mechanical properties can be obtained by varyin g its monomers types and content. In this paper, the effect of different soft segment length on influencing the structure prop erty relationship of polyurethane prepolymer was studied. The soft segment length was varied by using poly (propylene oxide) glycol havi ng different molecular weight and also by blending two polyols having similar che mical composition but of different molecular weight . The formation of the prepolymer was investigated by Fourier transform in frared spectroscopy (FTIR). The results reveal that with increasing soft segment length, the weight average molecular weight and sto rage time of the prepolymer increases, whereas the Brookfield viscosity decreases due to higher content of soft segment. The curing time was found higher in prepolymer having longer s oft segments due to lower isocyanate content. With increasing molecular weigh t of the soft segment, the phase separation between the hard and soft segment increases due to which the prepolymer produce low T g. The tensile strength of the polyurethane film dec reases whereas percent elongation increases with increase in soft segment length. The findings of the study will be beneficia l for understanding the role played by soft segment length on tailoring the stru cture and ultimately the properties of isocyanate t erminated polyurethane prepolymer.
10 citations
Cites background from "Synthesis and properties of polyest..."
...The concentration of lower molecular weight polyol has more influence on the viscosity than the concentration o f higher molecular weight polyol [3]....
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...It was reported in the literature that by varying the type and amou nt of polyol, diisocyanate, catalyst, reaction time and temperatu re, polyurethanes with a wide range of physico-mechanic al properties can be obtained [3]....
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...Also the number and si ze of diol molecules which condense with diisocyanate, determi nes the no of urethane linkages within the isocyanate termi nated prepolymer [3]....
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TL;DR: In this paper , the effects of amine type (diethylenetriamine and ethylenediamine) on the modification of lignin-based polyols, so as to provide an alternative to petroleum polyols and, in turn, increase functional groups and reduce their harm to humans' health and the environment.
Abstract: Polyols are groups of organic compounds which contain carbon and are randomly linked to other atoms, especially carbon-carbon and carbon-hydrogen. These compounds are mainly used as reactants to make other polymers. Among biopolymers, lignin is regarded as the base of a new polymer in polyol construction. The present study aimed to investigate the effects of amine type (diethylenetriamine and ethylenediamine) on the modification of lignin-based polyols, so as to provide an alternative to petroleum polyols and, in turn, increase functional groups and reduce their harm to humans’ health and the environment. To this aim, first, lignin was extracted from raw liquor. Next, the extracted lignin was reacted with diethylenetriamine (DETA) and ethylenediamine (EDA). Finally, the Mannich method was used for the reaction between amine lignin and propylene carbonate. The results of the Fourier Transform Infrared (FTIR) spectroscopy analysis showed that modification with DETA led to more structural change in lignin and peak 1100 indicates the presence of C–O bond related to urethane bonds in modified lignin. Moreover, adding propylene carbonate to aminated lignin did not result in much change in the results of the FTIR analysis. Additionally, urethane bonds can be seen in the results of GPC at 400°C–500°C. Furthermore, a slight decrease in thermal stability was observed in lignin modified with amine and propylene carbonate, compared to the raw lignin sample.
1 citations
TL;DR: In this paper, the reaction of tetrabromophthalic, phthalic and maleic anhydrides with polyethylene glycol via melt condensation technique is described.
Abstract: Hydroxy terminated polyesters were prepared by the reaction of tetrabromophthalic, phthalic, and maleic anhydrides with polyethylene glycol via melt condensation technique. They were characterized by hydroxy number, and intrinsic viscosity measurements. Also, the fire retardancy of polyesters was evaluated as varnish films on plywood strips. The polyesters were reacted with excess toluene ‐2, 4‐ diisocyanate to yeild isocyanate terminated prepolymers which were subsequently reacted with 5, 5‐ dihydroxymethyl‐2‐trichloro‐methyl‐1,3‐ dioxane or ethelene diamine. These polymers were characterized by Ir and 1H NMR spectra, viscosity measurements, and thermogravimetric analysis.
1 citations
References
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TL;DR: In this article, a kurze Ubersicht uber die Verarbeitung und die Anwendungsmoglichkeiten dieser neuen Klasse von Elastomeren gegeben.
Abstract: Es wird dargelegt, das man mit dem Diisocyanat-polyadditionsverfahren neuartige hochelastische Stoffe von bemerkenswerten Eigenschaften erhalt, wenn man lineare Polyester aus aliphatischen Dicarbonsauren und Glykolen mit einem Uberschus spezieller „sperriger” Diisocyanate in Gegenwart von wenig Wasser umsetzt. Die endstandig bifunktionellen Polyester reagieren zunachst mit dem Diisocyanat unter Kettenverlangerung. Die Vernetzung kommt uber die aus Isocyanat-Gruppen und Wasser entstehenden Harnstoff-Gruppierungen zustande, die mit Diisocyanaten weiterhin in Reaktion treten. Der Chemismus dieses Verfahrens wird eingehend erortert. Auserdem wird eine kurze Ubersicht uber die Verarbeitung und die Anwendungsmoglichkeiten dieser neuen Klasse von Elastomeren gegeben.
54 citations
TL;DR: In this paper, it was shown that polyisobutylene can form a glass, with the same transitions in thermal properties characteristic in the vitrification of substances of low molecular weight.
Abstract: Polyisobutylene, with an average molecular weight of about 4900, is at room temperature a highly viscous liquid. When cooled, it has been found to form a glass, with the same transitions in thermal properties characteristic in the vitrification of substances of low molecular weight. The heat capacity of polyisobutylene has been measured from 118°K to 295°K. It increases by 32 percent between 192°K and 202°K. The thermal expansion coefficient of polyisobutylene has been measured from 160°K to 300°K. It increases by 200 percent between 185°K and 205°K. The mean temperature of transition corresponds to a viscosity of about 1013 poises, in agreement with a rule observed generally for glass‐forming materials. The factors on which the transition temperature depends are discussed.
39 citations
37 citations
TL;DR: In der 6. Mitteilung uber Polyurethane wurde beschrieben, das lineare Polyester aus Adipinsaure and einfachen Glykolen durch einen Uberschus an Diisocyanaten, vor allen Dingen durch Naphthylen-1,5-diisocyaat, gleichzeitig verlangert and in sog.
Abstract: In der 6. Mitteilung uber Polyurethane wurde beschrieben, das lineare Polyester aus Adipinsaure und einfachen Glykolen durch einen Uberschus an Diisocyanaten, vor allen Dingen durch Naphthylen-1,5-diisocyanat, gleichzeitig verlangert und in sog. „Isocyanatpolyester” uberfuhrt werden konnen, welche an ihren Enden Isocyanatgruppen tragen. Wahrend nun damals die Vernetzung zum gummielastischen Kunststoff (Vulcollan) mit Wasser vorgenommen wurde, beschaftigt sich die vorliegende Arbeit mit anderen Vernetzungsmitteln wie z. B. Glykolen, Aminoalkoholen, Diaminen u. anderen bifunktionellen Verbindungen. Der Vernetzungsmechanismus wird fur jeden Fall diskutiert; es wird gezeigt, das die chemische Natur des Vernetzungsmittels auf die Eigenschaften des Vulcollans einen wesentlichen Einflus ausubt. Der Verarbeitung werden durch die angegebenen Verfahren neue Wege gewiesen, insbes. ist ein losungsmittelfreies Vergiesen des Vulcollans moglich geworden.
17 citations
TL;DR: Several N-substituted diisopropanolamines were prepared by reacting aqueous solutions of amines with excess propylene oxide at ordinary pressure but higher N-saturated diisOPO had to... as discussed by the authors.
Abstract: Several N-substituted diisopropanolamines were prepared by reacting aqueous solutions of amines with excess propylene oxide at ordinary pressure but higher N-substituted diisopropanolamines had to ...
7 citations