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Integral‐skin polyurethane foams
Author(s) -
Marciano J. H.,
Reboredo M. M.,
Rojas A. J.,
Williams R. J. J.
Publication year - 1986
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760261102
Subject(s) - polyurethane , blowing agent , materials science , composite material , vaporization , mold , polymerization , kinetics , thermodynamics , polymer , classical mechanics , physics
A model describing the expansion of a polyurethane (PU) foam in a closed mold is developed. An energy balance is stated, together with constitutive equations for the vaporization rate of the foaming agent and the polymerization kinetics. A numerical solution is obtained for an experimentally‐characterized PU formulation. It is shown that in order to avoid premature gelling or undesirable density distributions, the wall temperature must be close to the initial one. The relative fraction of skin in the foam may be increased by decreasing the part thickness or by adding less catalyst or more blowing agent to the formulation. Factors affecting cream, rise, and process times are discussed.