Gel permeation chromatographic analysis of polyurethane prepolymer synthesis kinetics. I. The effect of catalyst

Thompson, Corley M.; Taylor, Sue G.; McGee, W.W.

doi:10.1002/pola.1990.080280209

Cited by 27 publications

(7 citation statements)

References 8 publications

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“…Several studies have used size exclusion chromatography (SEC) to follow the change in molecular weight distribution with time in order to observe reaction kinetics. − SEC has also been used to confirm the molecular weight distribution in model chain extension reactions between butanediol and diisocyanate. , Surprisingly, we know of no studies that have confirmed whether polyurethane prepolymers exhibit the most probable distribution when prepared in the bulk.…”

Section: Introductionmentioning

confidence: 99%

Effects of Reaction Temperature on the Formation of Polyurethane Prepolymer Structures

Heintz¹,

Duffy²,

Hsu³

et al. 2003

Macromolecules

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For the first time, the molecular weight distribution and extent of side reactions have been quantified in polyurethane prepolymers. A combination of NMR, size exclusion chromatography, and mass spectrometry has been used to measure the molecular weight distribution. The values obtained are consistent with Flory's step polymerization theory. The type and amount of side reactions as a function of reaction temperature have also been investigated. At low temperature of reaction, the amount of branches arising from allophanate linkages is negligible. With only a relatively modest change in reaction temperature, this type of side reaction increases dramatically, so that at 145 °C as much as 10% of the nitrogens participate in allophanate linkages. The effect of this reaction on the molecular weight distribution was also measured. Upon formation of these side products, the molecular weight distribution broadens and the average increases. In this prepolymer system, the reactivity is independent of molecular weight.

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Section: Introductionmentioning

confidence: 99%

Effects of Reaction Temperature on the Formation of Polyurethane Prepolymer Structures

Heintz¹,

Duffy²,

Hsu³

et al. 2003

Macromolecules

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“…The potential of SEC as an analytical tool to be applied to oligomers was recognized in literature 11–13…”

Section: Methodsmentioning

confidence: 99%

Modeling and simulation of urethane acrylates synthesis. II. Kinetics of uncatalyzed reaction of toluene diisocyanate with a polyether diol

Grepinet

Pla

Hobbes

et al. 2001

J of Applied Polymer Sci

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Toluene diisocyanate reacts with poly(propylene glycol) during the synthesis of some urethane acrylate oligomers. The present work deals with kinetic studies and molecular characterization of the uncatalyzed bulk reaction of these two difunctional monomers. Back titration and H 1 -NMR are used to follow the reaction of the different isocyanate groups with an alcohol group belonging to poly(propylene glycol) and to allow a good description of the urethane groups evolution. The global reaction rate as well as that of each individual isocyanate group are well described by a second-order equation. Kinetic constants were calculated by using the software SIMUL-BATCH ® . The reaction of two difunctional monomers leads to the formation of oligomers of different polymerization degrees, opposite to the reaction of TDI with a monoalcohol. Thus, another approach was developed to characterize the oligomers by size exclusion chromatography and to calculate the molecular weight distribution by using a combination of kinetic and probabilistic arguments.

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“…7,8 Surivet et al 9 used SEC measurements to investigate the kinetics of the reaction between H 12 MDI and benzyl alcohol (BZA) in bulk. Mixtures containing 1 mol H 12 MDI and 1 mol BZA (that is NCO : OH ϭ 2) were studied according to a simple scheme (Scheme 1).…”

Section: Isocyanate-terminated Prepolymersmentioning

confidence: 99%

New segmented polyurethane ureas based on 4,4?-dicyclohexylmethane diisocyanate and on various soft segments

Samson

Méchin

Pascault

1998

J. Appl. Polym. Sci.

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Linear segmented polyurethane ureas were prepared from 4,4Ј-dicyclohexylmethane diisocyanate (H 12 MDI), 4,4Ј-diamino-3,3Ј-dicyclohexyl methane (3DCM), and various hydrophilic and hydrophobic soft segments. Kinetic studies of the synthesis of the diisocyanate-terminated prepolymers revealed that the use of too little reactive polyols (that is, polyoxypropylene that bears secondary hydroxyls) could be rather tricky; the noncatalyzed reaction is very slow, but the use of a catalyst soon triggers the formation of side products, and the processing window consequently becomes quite short. Microcalorimetric and dynamic mechanical measurements showed that all the materials were highly phase-segregated elastomers and displayed good mechanical properties up to high temperature (typically 180°C), provided that they had been postcured properly; in this respect, the dramatic effects of isolated (nonchemically linked) hard segments, as well as of too low postcuring temperatures, were demonstrated. Polyurethane ureas compare well with polyureas, and their synthesis can be a good way to cope with the lack of well-adapted commercial diamino-terminated prepolymers.

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Gel permeation chromatographic analysis of polyurethane prepolymer synthesis kinetics. I. The effect of catalyst

Cited by 27 publications

References 8 publications

Effects of Reaction Temperature on the Formation of Polyurethane Prepolymer Structures

Effects of Reaction Temperature on the Formation of Polyurethane Prepolymer Structures

Modeling and simulation of urethane acrylates synthesis. II. Kinetics of uncatalyzed reaction of toluene diisocyanate with a polyether diol

New segmented polyurethane ureas based on 4,4?-dicyclohexylmethane diisocyanate and on various soft segments

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