\nThe following is by my understanding.<\/p>\n
\nThe other day I was handling some polystyrene foam that arrived in a package. Like one would expect, it had been fitted around the package’s contents to protect them from damage. Said product had been unpacked, and the polystyrene remained.<\/p>\n
\nI noticed, as I handled it, how strong it was relative to its mass. I decided to look it up.<\/p>\n
\nIt turns out that one-pound polystyrene foam has a shear strength of around 20PSI. It’s a pound per cubic foot.<\/p>\n
\nBy way of comparison, Douglas fir has sheer strength of around 900PSI. However, it’s around 29 pounds per cubic foot.<\/p>\n
\nSo, Douglas fir has greater shear strength by weight, perhaps by a factor of around 1.5. However, for temporary set-ups, such as forms to hold wood parts in place for fastening, polystyrene could be used effectively.<\/p>\n
\nSource:<\/p>\n
Foam Factory. (Oct 12, 2014). Polystyrene Foam (EPS) Physical Data Sheet.<\/em> https:\/\/canada.foambymail.com\/polystyrene-foam-sheet.html<\/a><\/p>\n