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Journal ArticleDOI

Studies on isothermal urethane polymerization

01 Apr 1991-Polymer-plastics Technology and Engineering (Taylor & Francis Group)-Vol. 30, pp 227-238
TL;DR: In this article, a polyurethane reaction between a new polyol and TDI under isothermal conditions was investigated, where the progress of the reaction was monitored by following the viscosity as well as the monomer conversion.
Abstract: Polyurethane reaction between a new polyol and TDI under isothermal conditions was investigated. The progress of the reaction was monitored by following the viscosity as well as the monomer conversion. Viscosity variations were measured by means of a cone-and-plate viscometer while conversion was estimated by IR technique. An already reported empirical relationship between these two was verified. Stockmayer's formula for weight average molecular weight of a linearly polycondensing system was used to find molecular weights at every stage of the reaction. The interdependence of viscosity and weight average molecular weight was confirmed, and the value of the index m was obtained.
Citations
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Journal ArticleDOI
TL;DR: In this article, the order of polyurethane reactions involving a new polyol and TDL conversion of isocyanate by uncatalyzed polymerization under isothermal conditions was monitored by IR spectrometry and titration.
Abstract: Kinetics and rheological studies were carried out on polyurethane reactions involving a new polyol and TDL Conversion of isocyanate by uncatalyzed polymerization under isothermal conditions was monitored by IR spectrometry and titration. Viscosity changes of the reaction mixture were followed by a digital cone-and-plate viscometer under identical conditions. Conversion and viscosity were found to follow a power relationship. A relationship involving the order of the reaction n that connects the viscosity with time was derived. This provides a new viscometric method to find the order of the reaction. The order of the reaction determined by this method was very close to the values obtained by a fractional-life method already reported.

4 citations

References
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Journal ArticleDOI
TL;DR: In this article, a model for pressure rise, extent of reaction and temperature changes during filling and curing in thin rectangular molds for the reaction injection molding (RIM) process is developed.
Abstract: A model is developed for pressure rise, extent of reaction and temperature changes during filling and curing in thin rectangular molds for the reaction injection molding (RIM) process. The predictions of the model are shown to be in good agreement with experimental results obtained for several intrumented molds using polyurethane RIM chemical systems. The relevant dimensionless groups are identified. Criteria for good mold filling are developed.

203 citations

Journal ArticleDOI
TL;DR: In this article, the theory of molecular distribution in condensation polymers has been extended to include systems of a rather general type, and the expression for the distribution and the weight-average molecular weight are given.
Abstract: The theory of molecular distribution in condensation polymers has been extended to include systems of a rather general type. Equations for the distribution and the weight-average molecular weight are given.

134 citations

Journal ArticleDOI
TL;DR: In this paper, a trifunctional poly-e-caprolactone polyol was polymerized with a chain-extended 1,6-hexane diisocyanate, and the rheology followed by cone and plate flow.
Abstract: Trifunctional poly-e-caprolactone polyol was polymerized with a chain-extended 1,6-hexane diisocyanate, and the rheology followed by cone and plate flow. Viscosity was found to be independent of shear rate up to at least 102 N.s/m2 (103 poise) and 30s−1. Extent of reaction was monitored by a periodic titration for isocyanate groups. Using branching theory, viscosity was related to extent of reaction and temperature. Such relations should be useful for process models. Normal force data for the curing system are also reported.

101 citations

Journal ArticleDOI
TL;DR: In this article, the kinetics of the dibutyltin dilaurate catalyzed bulk polymerization of 4,4′-diphenylmethane diisocyanate (MDI) with poly-ϵ-caprolactone were studied by infared spectroscopy and adiabatic temperature rise.
Abstract: The kinetics of the dibutyltin dilaurate catalyzed bulk polymerization of 4,4′-diphenylmethane diisocyanate (MDI) with poly-ϵ-caprolactone were studied by infared spectroscopy and adiabatic temperature rise. The overall reaction order was found to change from 3/2 to 2 with increasing temperature. At temperatures above 80°C, the order with respect to catalyst was found to decrease with concentration from 1 to 1/2. The results were consistent with a Michaelis Menten type kinetic scheme.

81 citations

Journal ArticleDOI
TL;DR: In this article, an approach based on polymerization kinetics and the corresponding solution rheology and phase diagrams is proposed for predicting rheological changes during ionic, condensation, and free-radical polymerization.
Abstract: Parameters are developed for predicting rheological changes during ionic, condensation, and free-radical polymerization. Polymerization is viewed as changes in molecular weight and concentration for polymer solutions. Polymerization data in the laboratory and in tubular reactors are shown to be consistent with the proposed rheokinetic theory. This approach is based on polymerization kinetics and the corresponding solution rheology and phase diagrams.

49 citations