Morphological and performance measures of polyurethane foams using X-ray CT and mechanical testing.
Meso-scale structure in polymeric foams determines the mechanical properties of the material. Density variations, even more than variations in the anisotropic void structure, can greatly vary the compressive and tensile response of the material. With their diverse use as both a structural material and space filler, polyurethane (PU) foams are widely studied. In this manuscript, quantitative measures of the density and anisotropic structure are provided by using micro X-ray computed tomography (microCT) to better understand the results of mechanical testing. MicroCT illustrates the variation in the density, cell morphology, size, shape, and orientation in different regions in blown foam due to the velocity profile near the casting surface. "Interrupted" in situ imaging of the material during compression of these sub-regions indicates the pathways of the structural response to the mechanical load and the changes in cell morphology as a result. It is found that molded PU foam has a 6 mm thick "skin" of higher density and highly eccentric morphological structure that leads to wide variations in mechanical performance depending upon sampling location. This comparison is necessary to understand the mechanical performance of the anisotropic structure.
Los Alamos National Laboratory,Polymers and Coating Group,Materials Science and Technology Division,P.O. Box 1663,MS E549,Los Alamos,NM 87545,USA.
Brian M
BM
Patterson
Los Alamos National Laboratory,Polymers and Coating Group,Materials Science and Technology Division,P.O. Box 1663,MS E549,Los Alamos,NM 87545,USA.
Kevin
K
Henderson
Los Alamos National Laboratory,Polymers and Coating Group,Materials Science and Technology Division,P.O. Box 1663,MS E549,Los Alamos,NM 87545,USA.
Robert D
RD
Gilbertson
Los Alamos National Laboratory,Polymers and Coating Group,Materials Science and Technology Division,P.O. Box 1663,MS E549,Los Alamos,NM 87545,USA.
Stephanie
S
Tornga
Los Alamos National Laboratory,Polymers and Coating Group,Materials Science and Technology Division,P.O. Box 1663,MS E549,Los Alamos,NM 87545,USA.
Nikolaus L
NL
Cordes
Los Alamos National Laboratory,Polymers and Coating Group,Materials Science and Technology Division,P.O. Box 1663,MS E549,Los Alamos,NM 87545,USA.
Manuel E
ME
Chavez
Los Alamos National Laboratory,Polymers and Coating Group,Materials Science and Technology Division,P.O. Box 1663,MS E549,Los Alamos,NM 87545,USA.
Zachary
Z
Smith