Flexible polymer foam

The material. Polymer foams are made by the controlled expansion and solidification of a liquid or melt through a blowing agent; physical, chemi­cal, or mechanical blowing agents are possible. The resulting cellular mate­rial has a lower density, stiffness, and strength than the parent material, by an amount that depends on its relative density—the volume fraction of solid in the foam. Flexible foams can be soft and compliant, the material of cush­ions, mattresses, and padded clothing. Most are made from polyurethane, although latex (natural rubber) and most other elastomers can be foamed.

Composition

Hydrocarbon.

General properties

Density

Price

Mechanical properties

Young’s modulus Yield strength (elastic limit) Tensile strength Compressive strength Elongation Hardness—Vickers Fatigue strength at 107 cycles Fracture toughness

Thermal properties

Melting point Glass temperature Maximum service temperature Thermal conductor or insulator? Thermal conductivity Specific heat capacity Thermal expansion coefficient

Electrical properties

Electrical conductor or insulator? Electrical resistivity Dielectric constant Dissipation factor Dielectric strength

Flexible latex foams are used for cushions, mattresses, and packaging.

Ecoproperties: material

Embodied energy, primary production

*104 –

115

MJ/kg

CO2 footprint, primary production

*4 –

4.8

kg/kg

Water usage

*181 –

544

l/kg

Eco-indicator

460 –

500

millipoints/kg

Ecoproperties: processing

Polymer molding energy

*6.92 –

8.38

MJ/kg

Polymer molding CO2

*0.55 –

0.67

kg/kg

Polymer extrusion energy

*2.71 –

3.28

MJ/kg

Polymer extrusion CO2

*0.21 –

0.26

kg/kg

Recycling

Recycle fraction in current supply

0.1

О/

%

Typical uses. Packaging, buoyancy, cushioning, sleeping mats, soft furnish­ings, artificial skin, sponges, carriers for inks and dyes.