|CNT-enhanced stock shapes demonstrate enhanced performance.|
Trumpeted as a significant enabling material for next-generation medical devices, carbon nanotubes (CNTs) are actually already influencing the market. Although several companies have ventured into the area of CNT-enhanced materials, compounder Entegris Inc. claims that its proprietary technique ensures uniform dispersion of CNTs in the base polymer for enhanced performance. Now, a partnership between the company and converter Quantum Polymers has also resulted in the expanded availability of these CNT-enhanced polymers in easily processed stock shapes for use in medical equipment applications.
At the core of Quantano extruded products are Entegris’s CNT-enhanced Tego polymers. “These materials have this high aspect ratio where they’re very long but they’re also very flexible,” explains Shawn Cheesman, Entegris general manager, Tego polymers. “What makes our materials different from others is getting the dispersion of this product into the polymer. Think of something that is 15,000 times smaller than the diameter of a human hair and you’re trying to get that product dispersed well into the polymer; it’s not easy.”
Dispersion difficulty often stems from the tendency of CNTs to create bundles or agglomerates. Compared with other compounders, however, Entegris believes that its dispersion process is more effective at breaking down agglomerates into smaller pieces and then distributing them evenly throughout the polymer. This approach, Cheesman notes, helps to optimize the desirable properties of the base material.
CNTs can enhance these inherent properties of the polymer without compromising performance. “In some applications, an additive can actually make the base polymer weaker, for example,” Cheesman says. “[Or] a base polymer such as PEEK is well known for its lubricious nature. The nanotubes, because of the [uniform] dispersion, help to maintain some of that lubricious nature of the base polymer, whereas if you put in a carbon fiber or carbon powder, you lose some of that lubricious nature.”
Supported by uniform CNT dispersion, the enhanced materials can offer improved mechanical strength, dimensional stability, and homogeneous conductivity for good electrostatic discharge performance. “Carbon nanotubes by themselves conduct electricity better than copper and conduct heat better than diamond,” Cheesman states. “They’re good thermal conductors to dissipate heat from the polymer, unlike many other additives.”
The enhanced CNT-filled polycarbonate, polyetherimide, and PEEK materials are also inherently clean polymers, according to Hemant Bheda, president and CEO of Quantum Polymers. He notes that the lack of debris or particulation establishes the materials as suitable for a variety of parts for medical equipment applications. Supplied by Quantum in extruded rod and plate forms, the easily processed Quantano materials can also replace metal components in some applications.
Published in MPMN, June/July 2010, Volume 26, No. 5
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