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Boosting flow and flexibility


Two new polyolefin plastomers (POPs) from Dow Chemical?Affinity GA 1900 and 1950?promise to add higher flow, greater flexibility, and improved mechanical properties when blended or compounded into other materials, according to Michael Levinson, global business development manager, plastics. Combining low molecular weight, low crystallinity, and low density, the materials can be added to olefinics such as TPO, ethylenes such as SEBS and TPV, and engineering thermoplastics such as nylon, polyester, and PET.

Selim Yalvac, development leader, plastics, explains that the GA designation represents a new polymer. "While all Affinity POPs are based on Dow?s Insite single-site catalyst platform, the GA Series has a completely different combination of properties that can?t be found currently in any other product," he says.

Dow foresees several uses for the new materials. As a modifier, they can be blended at the press or added at the compounding stage to improve flow, flexibility, and properties such as toughness. In one study, when 15% Affinity GA was added to Kraton SEBS, it increased tensile strength by a factor of four and elongation by a factor of five, eliminating brittleness?a trade-off found with wax and oil modifiers.

For TPOs, which typically have a rubber modifier, replacing 25% of the rubber component with Affinity GA reportedly boosts flow with no loss of impact properties. For engineering thermoplastics, the materials are highly blendable.

Another use is as a carrier for colors and additives in masterbatches. With melting points of 68C and 70C, the materials have high filler loading capabilities, Levinson says, making them appropriate for colors and additives that are hard to load with a traditional PE carrier.

"GA POPs can be highly loaded and still give good dispersion," he says. With relatively low melting points for the GA materials, they can also be used as carriers for temperature-sensitive additives such as crosslinking and blowing agents, he adds.

Carriers for metal and ceramic injection molding feedstocks are another potential application for the new materials. Studies carried out at Penn State under the supervision of Randall German show clean burning and high loading capabilities when filled with metal or ceramic powders.

Several compounders have already adopted these materials, according to Dow. No special blending equipment or predrying is required to blend them at the press.?MM

Dow Chemical, Midland, MI
(800) 441-4369
www.dowaffinityga.com

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