1. Foam structure vs. lightweight structure

1.1 MD / HD lightened structure

If we combine 200 cm ³ of air and 800 cm ³ of polystyrene PS in a box (figure 1 -a), we obtain a mixture of 1,000 cm ³ with a weight of 840.56 g (air: 2.8 g/1,000 cm ³ and PS: 1,050 g/1,000 cm ³ ). In other words, a new material with a density of 0.84 g/cm ³ has been created, whose structure corresponds to that of a 1,000 cm ³ box enclosing a 200...