Walton, KY - Since high temperatures can cause certain foams to shrink, degrade or soften to the point of being unusable, Zotefoams Inc., the world's leading manufacturer of cross-linked block foams, recently conducted a series of tests on its ZOTEK® N B50 line of foams in order to measure product performance characteristics at high temperatures. The tests included thermal dimensional stability, dynamic mechanical analysis (DMA), and degradation of mechanical strength through long-term heat aging.
The Dimensional Stability at elevated temperatures is important in many applications. ZOTEK® N B50 has a very low coefficient of thermal expansion relative to many other foams. As with all foams, it will exhibit shrinkage after exposure to higher temperatures. This is typically greater with increasing temperatures, longer exposure times and thinner foam material. Shrinkage was negligible (<1%) for long-term use at 130°C for the ZOTEK® N B50. At 160°C, shrinkage increased but remained small (up to 4% after 1000 hours) for thicknesses less than 10 mm. Even at 190°C during short-term exposure, shrinkage remains at acceptable levels (<5%).
As with all polymers, the mechanical stiffness (modulus) decreases with increasing temperature. After environmental conditioning, ZOTEK® N B50 foam loses much of its low temperature stiffness and maintains a relatively constant modulus over the temperature range 0°C to 180°C. Loss of mechanical stiffness becomes significant above 180°C, a full 50°C higher than expanded polypropylene (EPP) foams.
The rate of polymer degradation increases with increasing temperature, particularly when exposed to air. Degradation can lead to loss of strength and embrittlement. Degradation has been measured by means of loss of mechanical strength after long-term exposure to hot air. There is little effect on the strength of N B50 after long-term aging (1,000 hours) up to 130°C. Loss of strength becomes significant after longer periods at 160°C and above.
The environment and physical demands of an application are important when determining the upper usable temperature. Laboratory simulation has been conducted using generic tests to aid design. For a copy of the complete high-temperature performance test results, and for more information on the ZOTEK® N B50 line of high-performance polyamide foams, please contact your local Zotefoams representative at (800) 362-8358.
ZOTEK® N is Zotefoams' brand name for a range of foams based on cross-linked polyamide (nylon) that have a closed cell structure. ZOTEK® N B50 line of high-performance polyamide foams provide excellent thermal and chemical resistance, and can be thermoformed into simple or complex parts.
Zotefoams Inc. is a wholly-owned subsidiary of Zotefoams plc (LSE: ZTF). Zotefoams is the premier manufacturer of cross-linked block foams. Its products are used in a wide range of markets including sports and leisure, packaging, transport, healthcare, toys, building, marine and the military. Through a unique production process, the Company produces foams that have controlled properties and are of a strength, consistency, quality and purity superior to foams produced by other methods. Zotefoams Inc. is responsible for product sales to the United States, Canada and Mexico. Zotefoams products include a wide range of foam densities, sizes, and physical properties. They also include fire retardant, conductive, and food contact approved foams. For more information, please go to www.zotefoams.com.