The Influence of Viscosity in Cell Opening of Flexible Molded Foams

Turner, Richard; Nichols, J.B.; Kuklies, R.A.

doi:10.1177/0021955x8902500202

Cited by 10 publications

(4 citation statements)

References 1 publication

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“…This embedding of the melamine in the PU matrix on the one hand and the limited drainage caused by the increased viscosity on the other hand resulted in a decrease in the number of cells from 19.3 to 13.7 on average, and a decrease in the air permeability from 3.2 to 1.9 dm 3 min À1 . The decrease in air permeability caused by the reduced drainage rate at unfilled molded foams was also discussed by Turner et al [18]. Instead an increase in the number of cells caused by the more intensive nucleation of the forming CO 2 on the surface of the particles was not measurable.…”

Section: Characterization Of the Mechanical Propertiesmentioning

confidence: 75%

Flexible Polyurethane Foam with the Flame-retardant Melamine

König

Fehrenbacher

Hirth

et al. 2008

Journal of Cellular Plastics

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Flexible polyurethane (PU) foams are widely used in many industrial applications, such as upholstered furniture and mattresses, automotive applications, etc. The chemical nature of the PU, the high air permeability, and the high inner surface area of the foam structure cause this material to be highly flammable. Consequently, the application of flame retardants to flexible PU foams is an important issue. The use of halogenated flame retardants is not considered optimal, in part due to the high emission level and the possible phase-out by the European Risk Assessment Body. Consequently, melamine as a nonhalogenated flame retardant is applied more and more frequently. However, little data is available regarding the application of melamine as an additive in flexible PU. This paper is concerned with the influence of melamine on the synthesis of the PU foam and the resulting material-specific properties. Especially, the increase of viscosity and the high heat capacity of melamine lead to a decrease in foaming growth and rising height with increasing melamine content. This is caused by the reduced drainage rate between the struts and the plateau borders in the foam-forming process. Here, the increase in viscosity follows the Dougherty—Krieger equation with the intrinsic viscosity of k = 3.3. The mechanical properties such as density and compression strength increase with increasing melamine content. Other properties like tensile strength and elongation decrease because of the embedding of the melamine in the PU matrix, which weakens the structure. The air permeation and number of cells also decreases because of the thickened struts caused by the reduced drainage rate in the foaming process. Furthermore, the reaction between the amino groups of melamine and the isocyanate of the PU formulation was investigated by FTIR.

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Section: Characterization Of the Mechanical Propertiesmentioning

confidence: 75%

Flexible Polyurethane Foam with the Flame-retardant Melamine

König

Fehrenbacher

Hirth

et al. 2008

Journal of Cellular Plastics

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“…The bigger the flake size, much larger are the cells and higher the recession factor. On the other hand, melamine powders with small sizes are embedded on struts and joints and increase the viscosity and reduce the drainage rate, which consequently decreases the number of cells with bigger sizes [11]. Melamine powders with bigger size (bigger than struts and joints) are embedded inside the cell walls and open the cells.…”

Section: Reactivitymentioning

confidence: 99%

An Investigation on Reactivity, Mechanical and Fire Properties of Pu Flexible Foam

Bashirzadeh

Gharehbaghi²

2009

Journal of Cellular Plastics

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Regarding the increasing demands for the fire resistance polyurethane foam for train and airplane industry and a serious planning to phase out the halogenated flame retardants (FR) because of high and toxic smoke generation, the use of halogen-free fire retardants have been more investigated in recent years. In this work, we have concentrated more on two well-known solid halogen-free fire retardants, expandable graphite, and melamine with two grades of each one and compare their performance in a variety of areas including reactivity, physical and mechanical properties, and fire behaviors and finally the tendency of each FR to have a synergetic effect with each other. The obtained results show that the addition of these two FR affect significantly on reactivity and physical—mechanical properties such as recession factor, expansion factor and compression load deflection (CLD P25/5), sag factor, compression set, tear strength, resilience, and more efficiently on fire behavior of flexible polyurethanes foam.

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“…The bigger the flake size, the larger the cells and higher the recession factor. On the other hand melamine powders with small sizes are embedded on struts and joints and increase the viscosity and reduce the drainage rate which consequently, decreases the number of cells with bigger sizes [10]. Melamine powders with bigger size (bigger than struts and joints) are embedded inside the cell walls and open the cells.…”

Section: Reactivitymentioning

confidence: 99%