Polyurethanes: A class of modern versatile materials

Seymour, Raymond B.; Kauffman, George B.

doi:10.1021/ed069p909

Cited by 129 publications

(67 citation statements)

References 2 publications

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“…Polyurethanes were first discovered by Otto Bayer and his colleagues in 1937 (Seymour and Kauffman, 1992). PUs are known for their wide range of properties including high tensile strength, abrasion resistance, and chemical resistance (Saraf andGlasser, 1984, Sarkar andAdhikari, 2001).…”

Section: Polyurethane (Pu)mentioning

confidence: 99%

The Effect of Plant Source on the Properties of Lignin-Based Polyurethanes

2018

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This work increases our understanding of the effect of plant source on the mechanical and morphological properties of lignin-based polyurethanes (PUs). Lignin is a polymer that is synthesized inside the plant cell wall and can be used as a polyol to synthesize PUs. The specific aromatic structure of the lignin is heavily reliant on the plant source from which it is extracted. These results show that the mechanical properties of ligninbased PUs differ based on lignin's plant source. The morphology of lignin-based PUs was examined using atomic force microscopy and scanning electron microscopy and the mechanical properties of lignin-based PU samples were measured using dynamic mechanical analysis and shore hardness (Type A). The thermal analysis and morphology studies demonstrate that all PUs prepared form a multiphase morphology. In these PUs, better mixing was observed in the wheat straw lignin PU samples leading to higher moduli than in the hardwood lignin and softwood lignin PUs whose morphology was dominated by larger aggregates. Independent of the type of the lignin used, increasing the fraction of lignin increased the rigidity of PU. Among the different types of lignin studied, PU with wheat straw soda lignin exhibited storage moduli ~2-fold higher than those of PUs incorporating other lignins. This study also showed that during synthesis all hydroxyl groups in the lignin are not available to react with isocyanates, which alters the number of cross-links formed within the PU and impacts the mechanical properties of the material.

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Section: Polyurethane (Pu)mentioning

confidence: 99%

The Effect of Plant Source on the Properties of Lignin-Based Polyurethanes

2018

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“…They are applied as automotive parts, in building and construction, in electrical and engineering applications, in the oil, chemical and food industry and in many other fields [1,2]. One of their major application areas is health care, where they are used mainly as medical devices in the form of encapsulants for hollow-fiber devices, dip-molded gloves and balloons, asymmetric membranes, functional coatings, and as extruded profiles for cardiovascular catheters [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Specific interactions, structure and properties in segmented polyurethane elastomers

Bagdi

Molnár

Sajó

et al. 2011

Express Polym. Lett.

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Abstract. Two sets of segmented polyurethane (PU) elastomers were prepared from 4,4!-methylenebis(phenyl isocyanate) (MDI), 1,4-butanediol (BD) and a polyester or a polyether polyol, respectively. The molecular mass of both polyols was 1000 g/mol. The stoichiometric ratio of isocyanate and hydroxyl groups was 1 and the polyol/total diol ratio changed from 0 to 1 in 0.1 steps. One step bulk polymerization was carried out in an internal mixer and the samples were compression molded for testing. The results proved that specific interactions determine the phase structure and properties of these materials. Crystallinity was approximately the same in the two types of polyurethanes and the amount of relaxing soft segments was also similar. The determination of interaction parameters from solvent absorption and differences in glass transition temperatures indicated stronger interaction between hard and soft segments in the polyester than in the polyether polyurethane. Larger transparency of the polyester PU indicated the formation of smaller dispersed particles of the hard phase. The larger number of smaller hard phase units led to the formation of more physical cross-links distributed more evenly in the polymer. These differences in the phase structure of the polymers resulted in stronger strain hardening tendency, larger strength and smaller deformations for the polyester than for the polyether polyurethane.

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“…Fully reacted polyurethane polymer is chemically inert. 2 We conducted an in vitro experiment by mixing the two liquids which the patient had consumed. We found that it expanded 30 times its initial volume over a period of 3 minutes, became hard and took the shape of the container used (Figure 4).…”

Section: Discussionmentioning

confidence: 99%

Esophago-gastric ‘Foam-Bezoar’ – report of a new entity

Chandramohan¹

2014

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Polyurethanes: A class of modern versatile materials

Abstract: The myriad applications of polyurethane coatings, foams, fibers, moldings, and elastomers demonstrate the versatility of urethane chemistry and the creativity of polymer scientists.

Cited by 129 publications

References 2 publications

The Effect of Plant Source on the Properties of Lignin-Based Polyurethanes

The Effect of Plant Source on the Properties of Lignin-Based Polyurethanes

Specific interactions, structure and properties in segmented polyurethane elastomers

Esophago-gastric ‘Foam-Bezoar’ – report of a new entity

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