Mold Filling Studies of Polyurea RIM Systems

Vespoli, N. P.; Alberino, L. M.; Peterson, Andrew A.; Ewen, J. H.

doi:10.1177/009524438601800304

Cited by 12 publications

(4 citation statements)

References 4 publications

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“…Such chemical systems yield materials with excellent mechanical properties (Grigsby and Dominguez, 1985;Ewen, 1985;Vespoli et al, 1986), but rapid gelation, generally occurring in less than 1 s (Vespoli et al, 1986;Pannone and Macosko, 1987), results in large domains of unreacted species in the RIM product material. Since the extent and control of fluid mechanical mixing is limited by the rising viscosity, any microscopic interfacial mixing process must somehow be controlled and optimized for successful molding of such chemical systems.…”

Section: Introductionmentioning

confidence: 99%

Microdispersive interfacial mixing in fast polymerizations

et al. 1988

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Interfacial activity between liquid reaction injection molding (RIM) reactants was observed using light microscopy. Diisocyanates were brought into contact with various diols and diamines in a thin (250 pm) gap. A dynamic phenomenon, rapidly producing a well-mixed, intermaterial phase, was discovered. It was revealed that the rate of growth of this newly formed region was dependent on both the rate of reaction and the physical properties of the initially formed product species at the reaction interface. Spontaneous interfacial mixing also occurred without chemical reaction when a reaction product was dissolved in "capped" contacting reactant liquids. It is believed that strong interfacial intermolecular forces, inducing flow through the polymerization product layer formed immediately upon reactant contact, are responsible for the initial explosiveness of this microscopic process. The range of eventual thicknesses of the mixed, interfacial region (100-800 pm) for various typical RIM systems indicates that this microscopic subprocess may be significant to the fate of the overall process.

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Section: Introductionmentioning

confidence: 99%

Microdispersive interfacial mixing in fast polymerizations

et al. 1988

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“…So far, attention has mostly been paid to the pressure build-up as well as the methods and techniques to detect the pressure in closed molds during foaming. [10][11][12][13][14][15] More fundamental research, both experimental as well as theoretical, on foaming power and the pressure generated in the foam bubbles during the foaming of 2C PU foam systems was conducted by Beruto et al 16 The influence of different surrounding pressures in the range 0.7-1.3 bar absolute pressure on the production of flexible 2C PU foams in slabstock production and its potential to control the density, and microstructural, and related properties was described by Cloakaerts and Mortelmans 17 in 1994. A linear relationship (Equation ( 1)) between the resulting density p of polyurethane slabstock foam and the surrounding pressure p p was derived employing the ideal gas theory 17…”

Section: Introductionmentioning

confidence: 99%

Structural and mechanical properties of flexible polyurethane foams cured under pressure

Rampf

Speck

et al. 2011

Journal of Cellular Plastics

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Flexible two-component polyurethane foam was synthesized under various extents of overpressure up to 2 bar. The influence of the pressure conditions on shrinkage and basic foam properties such as the relative density, microstructure, and ratio of open to closed pores as well as the elastic mechanical properties were investigated. The relationship between the relative foam density and the applied overpressure is shown to be rather linear. An abrupt change of the mainly open pore structure to essentially closed-cell foam was found in the narrow range between 50% and 60% relative density. A way to control the shrinkage properties of closed-cell foam via the extent and duration of overpressure applied during the foam synthesis was found and a hypothetic qualitative model describing the basic underlying mechanisms is given. Closed-cell flexible foam showing no effective shrinkage was produced this way. The achieved foam properties display an interesting potential for the application as e.g. gasket material.

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“…He assumed that the changes in the closing pressure of the hydraulic cylinder correspond to the pressure generated in the mould. Vespoli et al [5] built a Kistler pressure transmitter into the mould; however, it was not placed into the mould cavity but at the beginning of the feed bush. He intended to determine the viscosity changes from the pressure changes.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the pressure generated in the mould cavity during polyurethane integral skin foam moulding

Grőb¹,

Marosfalvi²

2008

Express Polym. Lett.

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Abstract. An industrial scale measuring system was set up to investigate the pressure arising in the mould cavity during polyurethane integral skin foaming. The system is able to measure the pressure arising in the mould cavity and the pressure distribution using a piezoresistive pressure sensor. The pressure distribution was measured at 18 points along the mould surface at constant production parameters. Then six production parameters, which affect the pressure, were investigated in detail with the Taguchi method of experimental design. The results of the design were processed by ANOVA (analysis of variance). Three major influencing parameters were estimated by regression analysis. Finally an equation was developed to give a good estimation to the pressure arising in the mould cavity.

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Mold Filling Studies of Polyurea RIM Systems

Cited by 12 publications

References 4 publications

Microdispersive interfacial mixing in fast polymerizations

Microdispersive interfacial mixing in fast polymerizations

Structural and mechanical properties of flexible polyurethane foams cured under pressure

Investigation of the pressure generated in the mould cavity during polyurethane integral skin foam moulding

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