Originally Published MPMNJanuary/February 2003

INDUSTRY NEWS

Flexible Molded Foam Has Good Memory

Elaine Paoloni

A state-of-the-art memory-foam material recovers its shape much more slowly than ordinary foams. The Bayfit 582 polyurethane system from Bayer Corp. (Pittsburgh, PA; www.bayer.com/polymers-usa) can be used to produce flexible, molded-foam medical products with viscoelastic properties that can be tailored to a manufacturer's requirements.


"Currently, there are very few molded-polyurethane foam systems that offer a viscoelastic formulation as an option," says Rick McHale of the polymers and chemicals communications department at Bayer Corp. "The viscoelasticperformance--the length of time it takes thefoam to return to its molded shape--can be adjusted to meet a manufacturer's needs." 


Tailored to manufacturers that have experience with diphenylmethane diisocyanate (MDI)-based polyurethane formulations, Bayfit 582 is supplied ready for processing. It is a full polyurethane system, consisting of an MDI-based isocyanate component and a polyether polyol component. The viscoelastic properties of the system can be customized to attain a manufacturer's desired rate of recovery. Additionally, the indentation force deflection of the system can be adjusted to achieve a consistency ranging from very soft to very firm.


The Bayfit 582 system produces low-resilience, cold-cure molded-polyurethane foams with low to medium load-bearing properties and excellent elongation, the company reports. It processes with standard mold releases and tooling similar to that used with conventional high-resilience polyurethane foam systems. It is suitable for molding both small and large parts. In addition, the foam can be pigmented in a variety of colors.


While its strength does not equal that of metal or rigid thermoplastics such as polycarbonate or ABS, Bayfit 582 could serve as an alternative to some other shape-memory materials, says McHale. "It depends on the physical-property requirements of the application." 


The Bayfit 582 system brings slow shape-recovery performance to a variety of products, including medical devices. "Devices that involve frequent or long-term human contact, such as armrests for wheelchairs and physical therapy equipment, ergonomic padding, patient-positioning aids, and other similar products, could benefit from padding molded with this viscoelastic material," says McHale. 

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