Chemistry that combines polyvinyl chloride (PVC) and polyolefin elastomers (POEs) has yielded a new series of flexible vinyl compounds that perform better than conventional plasticised PVC at high and low temperatures and avoid problems caused by plasticiser volatilisation or migration, Teknor Apex’s vinyl division announced.

The FreeFlex 4002 series includes four grades with Shore A hardness ratings of 81, 82, 85, and 90 (See table).
“While a degree of plasticiser loss is acceptable in many applications for flexible vinyl, the resulting falloff in mechanical properties, though typically marginal, has limited or prevented use of conventional compounds in applications that demand outstanding performance at temperature extremes or after outdoor exposure,” said industry manager Philip Morin.
 “Because the flexibility of FreeFlex compounds is inherent in their elastomeric component, products manufactured from them avoid embrittlement and provide as-new performance after prolonged service under such challenging conditions.”
Potential applications include hose and tubing and sheet products such as tank and pond liners, added Morin. “FreeFlex compounds are particularly promising for applications involving transport or containment of fluids that have a chemical affinity with conventional plasticisers,” he said, “or in parts for assemblies in which plasticiser migration can mar the surface of adjacent components.”
The new compounds will be priced approximately 40 to 80 per cent higher than highperformance conventional vinyl with low-extractible, low-volatility polymeric plasticisers.
 The technology underlying new FreeFlex compounds involves 1) use of high-performance new-generation POEs that typically are immiscible with PVC, and 2) development of proprietary compatibiliser chemistry enabling Teknor Apex to alloy them with PVC. “Unlike plasticisers, the POEs in FreeFlex compounds stay permanently blended with PVC,” said technical manager Maryellen Cox, “making possible material systems that remain fully homogeneous throughout their end-use service life.”

Plasticisers typically constitute a third of flexible vinyl compounds by weight and vary in their rates of extractability.
The FreeFlex 4002 series is just the first in a broad range of compounds anticipated as a result of the new PVC/POE technology, according to Cox. “In comparison with plasticiser additives, our elastomeric alloy components make possible greater retention of elongation upon heat aging, greater resistance to embrittlement at very low temperatures, superior electrical properties as reflected by a lower dielectric constant, and improved chemical resistance. We intend to develop a range of other PVC/POE alloys, all of them designed to expand the applicability of PVC to product areas where conventional vinyl does not meet existing requirements.”

The Vinyl Division of Teknor Apex is a leading manufacturer of custom and standard compounds based on polyvinyl chloride (PVC) including Apex flexible vinyl products, Flexalloy vinyl thermoplastic elastomers (TPEs) and Fireguard low-flame, low-smoke compounds for wire and cable. Headquartered in Pawtucket, Rhode Island, US, the division is an international supplier to appliance, automotive, construction, medical, wire and cable, and other industrial and consumer applications. Parent company Teknor Apex is a privately held firm whose other plastics-related businesses include the chemical division (plasticisers), the thermoplastic elastomer division (TPE compounds), the specialty compounding division (compounds based on a wide range of polymers), and Teknor Color Company, a major supplier of colour concentrates to the plastics industry.