Polyurethane (PU) foam is created when isocyanate and polyol are reacted. It becomes polyurethane foam when gas is introduced, either via reaction of the isocyanate with water, or with blowing agents. General Plastics has a number of proprietary formulations which have been created for meeting a wide variety of thermal or physical property requirements.
Rigid PU foams are useful in composite constructions. Polyurethane foams are made in large blocks through either a continuous-reaction process or in a batch process. The blocks are then cut into sheets or other shapes. They may also be individually molded or cast into custom part shapes.
Integral-skin foams, or self-skinning foams, couple a high-density skin and a low-density core. Self-skinning foams are available in either flexible or rigid foam formulations. The skin is beneficial due to the ability to mold custom textures for decoration or to impart abrasion or chemical resistant properties.
Our Closed cell products are strong, durable, rigid, do not absorb water and are used for many different purposes. Their variety of applications lend themselves to industries such as such as marine, aerospace, construction, recreation, modeling and more. The other category of polyurethane foams, open celled, are used for load deflection applications, in industries such as aerospace, defense, automotive and others.
Please note that General Plastics does NOT produce or supply:
Foam densities range from approximately 2 to 60 lbs. per cubic foot (48 to 961 kg/m3). Unlike thermoplastic foams (PVC, SAN,), the unit cost of polyurethane foam increases in a linear fashion with density, so a 20-lbs.-per-cubic foot PU foam will be approximate twice the cost of a 10-lb. foam.
Foams of the same density can vary considerably in mechanical properties, depending on the foam production process. Different production methods may require unique chemical formulations and foam curing temperatures. When beginning your foam selection process, it is important to reference the information on the Technical Data Sheet to ensure that the appropriate foam type is being used to meet your application’s property requirements.
If flammability is a concern, find out what kind of blowing agent is being used to create cells in the foam: Many producers use carbon dioxide (a byproduct of the foam-making chemical reaction) to create cells in their foams. Other producers have changed blowing agents in their low-density foam manufacturing processes. Switching from chlorofluorocarbon (HCFC, HFC) to pentane can negatively impact the foam’s flame resistance.
General Plastics’ premier closed-cell rigid and self-skinning molded polyurethane foams are used for high-performance applications by original equipment manufacturers, particularly in the aerospace, defense, marine, nuclear and other industries. Typically, they are used in tooling and mold making; as composite core; prototyping material; for protection of explosive or radioactive materials; and as a wood substitute for three-dimensional signs, displays and sculptures.
General Plastics manufactures commercial high-density foam products that are eco-friendly. Our “green” content combines post-industrial, post-consumer and rapidly renewable material resources.
Find green content in General Plastics’ LAST-A-FOAM® FR-4500, FR-4600 (Sign Foam 4), FR-7100 and R-9300 foams series. The percentage of green content varies by product line and density.
For example:
For full details on these aspects of working with our HDU (high-density urethane) materials, please refer to our User Guide to Tooling and Molds.
The Tooling & Molds User Guide covers the following topics:
Our flexible foams are white, and most of our rigid foams are yellow. Depending on the quantity, we can also formulate specific colors. Be aware that exposure to UV lighting will darken the exterior color of these foams. If appearance is a concern, we recommend painting them with an opaque coating.
Our polyurethane foams accept any paint finish and absorb very little paint.
Recommended coatings include automotive or woodworking grades. For outdoor use, acrylic-latex paint or enamel works well.
Refer to our technical data sheets (TDS) for thermal properties of our foams. Note that these numbers are approximate, and we recommend that you test the product for your particular application.
Most General Plastics polyurethane foam series products are identified by their foam category, density and often other essential characteristics as follows:
Rigid Foam Products, with the exception of our TR-Marine foams, start “FR” for Flame-retardant Rigid, or just the letter “R” for rigid, followed by the series number and foam density:
Examples:
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