Are thermoplastic elastomers the perfect tubing replacement?

Mark Crawford, Eldon James Corporation, explains why thermoplastic elastomers (TPEs) offer the perfect tubing replacement as silicone supplies dwindle.

For the last few years, the silicone raw materials market has been highly turbulent. Many key components for making silicone elastomers such as siloxane are in critically short supply, leading to huge price fluctuations and frustrating supply issues which have pushed lead times on some silicone tubing products out as far as three to four months.

The source for much of this market unrest is China which is one of the largest silicone component producers in the world. Although China provides nearly 45% of the global production capacity for these materials, increasing Chinese domestic consumption has left less material available to export to other countries.

“A significant portion of the supply of these materials has been removed from the marketplace,” states Jonathan Kane, CEO at Polytek Development Corporation, a Pennsylvania-based manufacturer of specialty polymers, including silicones. “This has buyers scrambling to find supply and willing to pay whatever it takes to stay in business.”

This reduction, too, would be less of an issue if other suppliers had increased their manufacturing capacity for these components over the years.

"There are shortages everywhere in the market,” adds Len Rogers, supply chain manager for silicone, metal and metal fabrication for Michigan-based Freudenberg-NOK Sealing Technologies. “There has been no investment, no basic plants, no basic assets added in the past decade by any of the major suppliers. I think this is coming to fruition as demand continues to grow, to the point where the manufacturers are making some hard choices in where they supply and who they supply."

Additionally, China's Environmental Protection Administration is forcing silicone manufacturing facilities with high pollution levels to shut down for weeks or months to audit their procedures and enforce clean-up operations. Tariffs with China are also driving up silicone costs for U.S. manufacturers, and worries about the possibility of a prolonged trade war between the U.S. and China have companies concerned about both the long-term disruption to their supply chains and the increasingly higher costs they will have to reluctantly pass on to their customers.

Therefore, to deal with the ongoing silicone shortage, manufacturers will continue to raise prices in the short term in order to accommodate swings in material and energy costs, knowing that supplies will remain tight and lead times almost unbearable.

However, an increasing number of silicone manufacturers, material suppliers, and customers, who see the silicone shortage as a serious, costly, and long-term production problem, are choosing to be proactive by looking for cost-effective substitutes for silicone - especially TPEs.

The TPE alternative

Silicone has always been the gold standard for medical and pharma tubing until recently. Over the years plastic material manufacturers have improved alternative materials, such as TPE, which have similar properties compared to silicone but are easier to work with and less expensive. TPE, now that it has been engineered to be stable at higher temperatures, is becoming a preferred material for extruded tubing and offers a wider range of beneficial properties than silicone does.

 Both silicones and TPEs are soft flexible elastomers with very similar physical and chemical properties at room temperature. However, because TPEs are a special class of materials that consist of copolymers of plastic and rubber, they have a greater number of beneficial surface characteristics. TPEs can be compounded to meet very specific requirements for softness or hardness, flexibility, and stiffness. TPEs can be stretched to moderate lengths and then return to their original shape. They also provide better abrasion resistance than silicone (up to 95 durometer A), and can be repeatedly melt processed, which reduces material waste (compared to silicone which sets and then cannot be melted and reused again). A drawback to silicone is the tackiness of the surface, which attracts dirt, lint, and other debris. Although silicone and TPE are extruded in a similar fashion, silicone requires more steps and a curing process which adds time and cost. TPE is also more environmentally friendly than silicone and can be recycled.

Converting to TPE

For an increasing number of manufacturers, TPE is becoming an effective, lower-cost alternative to silicone. TPEs compete well with silicones for strength, temperature resistance and chemical resistance, and have performance advantages for characteristics such as flexibility/stiffness, abrasion resistance, softness/hardness and lighter weight. TPEs such as Eldon James’ Flexelene that are engineered for higher durometers with very low non-extractables are now approved for medical device and pharma applications.

Not only does TPE provide a wider range of beneficial properties compared to silicone, it has fewer environmental impacts and provides a more stable market, which results in shorter, more reliable lead times and faster time to market.