TORAYPEF® Polyolefin Foam

Technical Information | Low water-absorption and a great deal of buoyancy

Water-resistance

Ⅰ. Water absorption

Water absorption in TORAYPEF® is negligible because it is made from polyolefin, which absorbs little water, and because of its closed-cell foam structure. However, the sides or sliced surfaces of TORAYPEF® products are open foam cells. If these exposed open cells pick up water, it may create the appearance the material is absorbing water.

Ⅱ. Water permeability

Figure 1 shows the results of water permeability measurements.
The water permeability of low-density polyethylene is 5-6 g/m2 24 h/0.1 mm. The water permeability of TORAYPEF® is equivalent to that of a polyethylene sample having a real thickness of 0.1 mm. TORAYPEF® exhibits none of the increased water permeability one would expect from a foam product. Instead, its water permeability is about 1/100th that of polystyrene foam.

Figure 1: Relationship between apparent density and water permeability

These data are representative examples of measurement values obtained using specific conditions. The values should not be used as a standard.

Figure 1: Relationship between apparent density and water permeability

Electrical and acoustic properties

Ⅰ. Electrical properties

The dielectric breakdown strength of TORAYPEF® varies somewhat by grade but falls within the range of 3.0-5.0 kV/mm. Volume resistivity is within the range of 1016-1017 Ω·cm and 1017-1018 Ω, respectively. The dielectric constant and power factor are both very low values—1.03-1.2 and 0.0002, respectively.

Ⅱ. Acoustic properties

TORAYPEF® exhibits a great deal of acoustic effect in the upper and middle sound ranges (2-8 KHz). The sound-insulating property of an object is said to be proportional to the logarithm of the weight per unit surface area. However, TORAYPEF® actually insulates vibration and thus prevents the transmission of sound through a solid. As a result, TORAYPEF® is capable of a high degree of sound insulation despite its lightweight nature.

Figure 2: Sound absorbency of TORAYPEF® (30060)

These data are representative examples of measurement values obtained using specific conditions. The values should not be used as a standard.

Figure 2: Sound absorbency of TORAYPEF® (30060)