Polyurethanes are a family of resins that offer ruggedness, fast cure time and flexibility. Polyurethanes are easily foamed in a controlled process to produce a wide range of densities.
The chemistry is the reaction of two or more functional monomers (like an isocyanate with any hydroxyl groups) to yield the urethane linkage. The desired molecular weight determines how many units are extended. They molecularly bond very effectively with a variety of substrates and reinforcements.
The best processing equipment is dependant on the requirements of your product, which we would be happy to discuss with you.
Best Processes
Resin Transfer Molding (RTM), Reaction Injection Molding (RIM), Vacuum Infusion, Open Molding (Hand Lay-up/Spray-up), Liquid Composite Molding (LCM) and Compression/Injection. The best process for your product is a function of your tooling budget, part specification (such as dimensional tolerance and physical properties) and production volume.
Reinforcements
Glass, aramids and carbon. Sticks well to most reinforcements.
Special Design Considerations
Because polyurethanes are very strong they have extensive double bonding in the linkages and which results in high shrinkage. Tougher systems generally involve greater shrinkage. If you have questions about the impact of shrinkage on your part design, our dedicated team of design engineers can review the details and provide guidance for shrinkage allowance. MFG’s Technical Design Guide for FRP Composite Products and Parts provides in-depth information for product designers. You can download it on the bottom of this page.
Technical Details
Polyurethanes build glass transition temperature (Tg) without post cure considerations in several processes. Vinyl esters and urethanes are similar in many ways, yielding properties that build toughness. If you need high volumes per year (50,000 +) and very fast cycles, some degree of post curing may be necessary. This is a function on the cycle time required and the ultimate product requirements.
Cost Considerations
The cost of the polyurethane material is about 1.5 – 2X that of polyester resins.
Videos
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Facts About Styrene 2013
Educational video on the effects of styrene. This video is part of ACMA's Risk Communication Program that provides information tools about chemical health risks.
Resources
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Technical Design Guide for FRP Composite Products and Parts
Fiber glass (FRP) composite materials and processes are explained in detail. This design guide outlines various selection criteria with helpful technical data and comparisons to alternative materials.