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Chemical and physical blowing agents in structural polyurethane foams: Simulation and characterization
Author(s) -
Modesti M.,
Adriani V.,
Simioni F.
Publication year - 2000
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.11337
Subject(s) - blowing agent , materials science , polyurethane , composite material , pentane , isocyanate , flexural strength , molding (decorative) , methyl methacrylate , polymer , polymerization , organic chemistry , chemistry
Physical blowing agents such as n‐pentane and methyl formate and, for comparison, chemical blowing agents such as water were used to prepare structural polyurethane rigid foams of different densities by reaction injection molding. Experimental runs were carried out with formulations based on oligomeric isocyanate and a mixture of polyether polyols. The constitutive equations for the vaporization rate of the two blowing agents and the polymerization kinetics data are reported. Experimental results were compared with the prediction of a simplified theoretical model, and they showed a satisfactory agreement in terms of temperatures and density profile. All the specimens were characterized by physical‐mechanical properties such as hardness, impact strength, flexural strength and elastic modulus and the results were reported in function of the densities. The best mechanical performance were obtained with the physical blowing agents, due to a better density distribution profile and a thicker skin layer.