The Effects of Various Additive Components on the Sound Absorption Performances of Polyurethane Foams

Figure 7

Curves showing the sound absorption character of the PU foams with varying water contents. (a) Group 1 with water 3.8 parts by weight, (b) Group 2 with water 4.1 parts by weight, (c) Group 3 with water 4.4 parts by weight, and (d) Group 4 with water 4.7 parts by weight.