Rigid polymer foam

The material. Polymer foams are made by the controlled expansion and solidification of a liquid or melted 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. Rigid foams are made from polystyrene, phenolic, poly­ethylene, polypropylene, or derivatives of polymethylmethacrylate. They are light and stiff and have mechanical properties that make them attrac­tive for energy management and packaging and for lightweight structural use. Open-cell foams can be used as filters, closed-cell foams as flotation. Self-skinning foams, called structural or syntactic, have a dense surface skin made by foaming in a cold mold. Rigid polymer foams are widely used as cores of sandwich panels.

Composition

Hydrocarbon.

General properties

Density

78

– 165 kg/m3

Price

*12

– 24 USD/kg

Mechanical properties

Young’s modulus

0.08

– 0.2

GPa

Yield strength (elastic limit)

0.4

– 3.5

MPa

Tensile strength

0.65

– 5.1

MPa

Compressive strength

0.95

– 3.5

MPa

Elongation

2

– 5

%

Hardness—Vickers

0.095

– 0.35

HV

Fatigue strength at 107 cycles

*0.455

– 2.8

MPa

Fracture toughness

*0.0066

– 0.048

MPa. m1/2

Thermal properties

Glass temperature

67

– 157

°C

Maximum service temperature

67

– 157

°C

Thermal conductor or insulator?

Good insulator

Thermal conductivity

0.027

– 0.038

W/m. K

Specific heat capacity

1120

– 1910

J/kg. K

Thermal expansion coefficient

20

– 70

p, strain/°C

Rigid polymer foam is used as the core of the GFRP sandwich shell for ultra-lightweight designs such as this glider.

Typical uses. Thermal insulation, cores for sandwich structures, panels, partitions, refrigeration, energy absorption, packaging, buoyancy, floatation.