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Structural Foam Molding

September 13, 2017
Structural Foam Polyrethane Characteristics Target Applications
Two-component, MDI-based liquid systems Non-Impact Body Panels
Large part moldability Cab Roofs (Ext & Int)
Thick and thin wall substrates Interior Panels (Sound Deadening)
High Stiffness to weight ratio
In-mold coatings
High-gloss finish
Excellent surface quality
Styrene-free processing
Lower material & Labor cost
Higher productivity
High impact properties
Weight savings of 20-40% compared to traditional composites
Low thermal expansion properties
Mold behind Vinyl
Soft Feel
Sound Damping
671 730
Density, pcf 45 40
Flexural Modulus, psi 211,000 170,000
Tensile Strength, psi 3,800 2700
Elongation, % 7 10
Notched Izod, ft.-lb./in. 8 11
Heat Sag, 1 hour at 250F 4 overhang (mm.) 2.2 2.2
Die C Tear, pli N/A N/A
CLTE X 10E-6 44 50
Hardness (D scale) 72 70

Structural Foam systems use a blowing agent to make parts with a higher-density skin and a lower-density, microcellular core in a sandwich-like composition. The blowing agent activates when the formulation’s polyol component reacts with the isocyanate component.

This forms a polyurethane with a cellular, foamed structure. Structural foam and other rigid systems have hard, solid skins and are found in exterior panels, electronic and medical housings, automobile spoilers, skis, and other load-bearing applications. Structural foams are defined by their density.

Polyurethane foams range in density from as little as 2 pounds per cubic foot to as much as 55 pounds per cubic foot. The flexural modulus of structural polyurethane foams increase as the density increases.

An unreinforced structural polyurethane foam with a density of 15 pounds per cubic foot contains a flexural modulus around 30,000psi. 40 pounds per cubic foot foam has a flexural modulus of 170,000psi. The highest modulus seen in an unreinforced structural foam can be 250,000psi.

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