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Flexural properties of moldings of rigid polyurethane made by reaction injection molding
Author(s) -
Iida Makoto,
Gotoh Masao,
Yokono Hitoshi,
Miyano Yasushi
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.760261009
Subject(s) - materials science , flexural strength , composite material , bending , flexural modulus , three point flexural test , ultimate tensile strength , buckling , molding (decorative) , polyurethane , core (optical fiber) , beam (structure) , stress (linguistics) , structural engineering , engineering , linguistics , philosophy
Abstract Flexural properties of moldings made by Reaction Injection Molding (RIM), which are structural foams consisting of high density skin and low density core, were investigated by three‐point bending tests. Two failure modes were observed in bending tests of the moldings made by RIM, and they are classified as follows according to the density ratio of skin layer to core layer: the opposite side of the skin layer to which load was subjected failed by tensile stress: and the same side of the skin layer to which load was subjected failed by compressive stress, causing wrinkling or buckling. Then the conventional composite beam theory was applied to the former failure mode and Hoff s buckling theory to the latter, and equations were derived to predict the flexural properties of the structural foams, which involved buckling from the flexural properties of solid construction. In addition, it has been shown that there exists a density distribution that maximizes the flexural strength of the moldings made by RIM with a given overall density. The results obtained here should be useful to the optimum structural design of moldings made by RIM.