Diisocyanato dicyclohexylmethane: structure/property relationships of its geometrical isomers in polyurethane elastomers

Seneker, S. D.; Born, Liborius; Schmelzer, H. G.; Eisenbach, Claus D.; Fischer, Karl

doi:10.1007/bf00658285

Cited by 27 publications

(21 citation statements)

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“…Results reported by Seneker et al 14 showed that in this system, the ultimate tensile strength, elongation at break, and tear strength all increased with the increase of trans,trans isomer content of the diisocyanate. For example, a poly- Therefore, it appears that one needs to have a reasonable balance in phase separation and interfacial adhesion in order to achieve good mechanical properties in polyurethanes.…”

Section: Synthesis and Mechanical Properties Of Polyurethanesmentioning

confidence: 83%

“…The properties of these polyurethanes show a strong dependency on the isomeric ratio, with increasing trans,trans isomer content resulting in polyurethanes having improved mechanical properties. 14 There have been only a few studies in the past on polyurethanes based on H 12 MDI and nonpolar macrodiols, such as PDMS. [27][28][29][30] These studies have reported a high degree of phase separation in the materials due to decreased compatibility of the soft and hard segments.…”

Section: Introductionmentioning

confidence: 99%

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The effect of diisocyanate isomer composition on properties and morphology of polyurethanes based on 4,4′-dicyclohexyl methane diisocyanate and mixed macrodiols (PDMS-PHMO)

Adhikari

Gunatillake

Meijs

et al. 1999

J. Appl. Polym. Sci.

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Three series of polyurethanes were prepared having 42 wt % hard segments based on 4,4Ј-dicyclohexyl methane diisocyanate (H 12 MDI) with trans,trans isomer contents in the 13 to 95 mol % range and 1,4-butanediol chain extender. The soft segments were based on macrodiols poly(hexamethylene oxide) (PHMO, MW 696), ␣,-bishydroxyethoxypropyl polydimethylsiloxane (PDMS, MW 940), and two mixed macrodiol compositions consisting of 80 and 20% (w/w) PDMS. H 12 MDI with 35, 85, and 95% trans,trans isomer contents were obtained from commercial H 12 MDI (13% trans, trans) by fractional crystallization, and all polyurethanes were prepared by a one-step bulk polymerization procedure. The polyurethanes based on the commercial diisocyanate-produced materials soluble in DMF with molecular weights in the 53,655-75,300 range and generally yielded clear and transparent materials. The polyurethanes based on H 12 MDI with trans,trans contents of 35% or higher yielded materials insoluble in N,N-dimethylformamide (DMF) and were generally opaque. Mechanical properties, such as tensile strength and elongation at break, decreased with increasing trans,trans content, while the Young's modulus and Shore hardness increased. The polyurethanes based on mixed macrodiols yielded higher tensile properties than those of materials based on individual macrodiols. The best mechanical properties were observed for a polyurethane consisting of a soft segment based on PDMS-PHMO (80/20) and a hard segment based on commercial H 12 MDI and BDO. Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) were employed to characterize the polyurethane morphology. DSC results confirmed that the polyurethanes based on H 12 MDI with high trans,trans isomer were very highly phase separated, exhibiting characteristic hard segment melting endotherms as high as 255°C. The other materials were generally phase mixed. FTIR spectroscopy results corroborated DSC results.

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Section: Synthesis and Mechanical Properties Of Polyurethanesmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

The effect of diisocyanate isomer composition on properties and morphology of polyurethanes based on 4,4′-dicyclohexyl methane diisocyanate and mixed macrodiols (PDMS-PHMO)

Adhikari

Gunatillake

Meijs

et al. 1999

J. Appl. Polym. Sci.

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“…Thus, the main aim ofthis series is the experimental study of the phase morphology and the DMS in a systematic series of SPUs prepared from STFs of essentially similar chemical composition but different intrinsic flexibilities (i.e., 4,4'-dicyclohexylmethane diisocyanate, HMDI, with different contents of all-trans linkages, and 4,4'-diphenylmethane diisocyanate, MDI). Selected aspects of this issue were also discussed in some earlier studies of SPUs of other compositions (9)(10)(11)(12)(13)(14)(15).…”

Section: Introductionmentioning

confidence: 99%

Influence of the structure of soft and stiff chain fragments on properties of segmented polyurethanes. I. Phase morphology

Privalko

Привалко

Shtompel

et al. 1999

Polymer Engineering & Sci

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Model segmented polyurethanes (SPUs) prepared from either oxypropylene glycol oligomer or butylene adipate glycol oligomer, both of molar mass 2 kg/mol (soft fragments, SFT), and three different diisocyanates (all‐trans 4,4'‐dicyclohexylmethane diisocyanate, t, t‐HMDI‐1.0; HMDI with 20% of trans isomers, t, t‐HMDI‐0.2; and 4, 4'‐diphenylmethane diisocyanate, MDI) (stiff fragments, STF) were characterized by specific heat capacity measurements in the temperature interval 140‐540 K, and by wide‐angle and small‐angle X‐ray scattering at room temperature. Limited miscibility of SFT and STF chain components resulted in incomplete separation into a regular three‐dimensional macrolattice of STF‐rich microdomains and SFT‐rich microphases. The composition of STF‐rich microdomains was estimated by fitting the softening temperatures to the Couchman's equation, whereas the relative contents of SFT‐rich and STF‐rich microphases were assessed by comparing the specific heat capacity change at the glass transition temperatures to corresponding additive values. The overall degree of microphase separation, as well as the mean macrolattice spacings between STF microdomains decreased in the order, MDI > t, t‐HMDI‐1.0 ≫ t, t‐HMDI‐0.2. The conformation of STF fragments within the STF‐rich microdomains changed from nearly extended (for MDI) through slightly contracted (for t, t‐HMDI‐1.0) to strongly contracted (for t, t‐HMDI‐0.2).

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“…The morphology, and especially the hard domain structure, define the material properties of the thermoplastic PU elastomers. PU elastomers with 1,4-butanediol-linked HMDI hard segments are known for their excellent optical clarity, light stability and hydrolysis resistancy, especially the elastomers based on isomeric pure trans,trans-HMDI which show superior physical and mechanical properties (Seneker, Born, Schmelzer, Eisenbach & Fischer, 1992). The structure of the methanol-capped isomeric pure trans,trans-HMDI (Me-ttHMDI-Me) has been determined as a model for the structure of the trans,trans-HMDI/1,4-butanediol polymer.…”

Section: Introductionmentioning

confidence: 99%

Structure of trans,trans-4,4'-di(methoxycarbonylimino)dicyclohexylmethane: a model for trans,trans-4,4'-diisocyanatodicyclohexylmethane/1,4-butanediol-based units in polyurethane hard segments

Milius¹,

Steinlein²,

Eisenbach³

1994

Acta Crystallogr Sect B

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Diisocyanato dicyclohexylmethane: structure/property relationships of its geometrical isomers in polyurethane elastomers

Cited by 27 publications

References 1 publication

The effect of diisocyanate isomer composition on properties and morphology of polyurethanes based on 4,4′-dicyclohexyl methane diisocyanate and mixed macrodiols (PDMS-PHMO)

The effect of diisocyanate isomer composition on properties and morphology of polyurethanes based on 4,4′-dicyclohexyl methane diisocyanate and mixed macrodiols (PDMS-PHMO)

Influence of the structure of soft and stiff chain fragments on properties of segmented polyurethanes. I. Phase morphology

Structure of trans,trans-4,4'-di(methoxycarbonylimino)dicyclohexylmethane: a model for trans,trans-4,4'-diisocyanatodicyclohexylmethane/1,4-butanediol-based units in polyurethane hard segments

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