General Plastics Debuts Polyurethane Dielectric Material
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General Plastics Debuts Polyurethane Dielectric Material with High Thermal Processing Properties for RF Communications and Radome Applications

LAST-A-FOAM® RF-2200 series offers high-performance, lightweight insulative material with superb dimensional stability for protecting sensitive electronics in high-reliability environments

TACOMA, Wash. – September 7, 2017 – General Plastics Manufacturing Company, a global supplier of high-performance polyurethane foam products and composite parts, today introduced its advanced dielectric foam material for use in radomes, antennas and other critical radio frequency (RF) communication systems. The new LAST-A-FOAM® RF-2200 rigid foam series addresses the need for an RF-transparent protective layer with extended thermal processing capabilities. Initially offered at 3, 4 and 6 pounds per cubic foot sheets and blocks, the foam’s density may be tailored to other values to meet user’s specific dielectric constant and loss tangent requirements. It also provides a finer cell structure compared to some thermoplastic materials, as well as high dimensional tolerances and thermal stability, which are critical when creating sandwich panels and complex shapes to tight tolerances.

“As composites have become increasingly commonplace for lightweight structures, our new RF-2200 series is another example of how General Plastics looks at a wide spectrum of solutions to solve customers’ very technical problems,” said General Plastics President Mitch Johnson, Ph.D. “These low-density, high-strength foams are a solid step forward in processing higher-temperature composite prepregs, particularly for radomes and other radio frequency panels. Now customers have a core material to match and exceed their required properties.”

Greater performance and versatility

These materials are commonly used in sandwich panel configurations, which require elevated cure temperatures to press the material into panels. “The RF-2200 series foams are formulated with a Tg exceeding 350ºF, dramatically increasing their processing capabilities,” said General Plastics Head Engineer Joel Meyer, Ph.D. This means a high-temperature prepreg can be thermally-cured to easily form a panel with better dimensional stability than previously possible.

LAST-A-FOAM® RF-2200 is available in sheets and blocks as well as machined final core configurations.  General Plastics can also produce extremely large blocks, enabling customers to create very complex shapes. This represents a significant advantage over other materials which are available only in thinner sheets. Customers who rely on such products are limited to bonding sheets together, resulting in potentially problematic density gradients from sheet to sheet.

General Plastics’ newest foam series expands on the FR-3700 Performance Core and FR-7100 Multi-Use Foam series products currently used in radomes, all of which deliver proven transparency and structural durability with negligible impact on signal strength. In addition to supporting higher processing temperatures, the new RF-2200 materials provide a finer, more uniform cell shape compared to other offerings. This homogenous cell structure improves signal transmission and reception without interference from the surrounding material. These properties also enable the RF-2200 foams to protect sensitive electronics with an insulative material.

Expanding design opportunities

General Plastics has comprehensively characterized all of these polyurethane foams, giving it the ability to supply custom densities to satisfy the customer’s specific dielectric property requirements.  “If a customer comes to us and requests a material with a dielectric constant of 1.15 that they can drop into their design, we can tailor a material to meet that requirement,” Dr. Meyer said.

And, by demonstrating that the material is completely non-dispersive, the company can certify the dielectric constant of its material at specified frequencies. Certifications of performance of a specific sheet of material can be supplied upon request.

Protecting communications signals

As very high-performing electronics and communications become more pervasive, it is imperative to eliminate any holes in communication regardless of environment.  An insulative material that will not interfere with signal transmission or the electronics inside the devices are required for radomes and electronic devices based on land, water or air. These devices must be physically protected throughout the program’s life span from environmental elements such as rain, wind, dust, hail and other damaging impact.

Because LAST-A-FOAM® products are closed-cell polyurethanes, they do not absorb water. No matter whether these durable, low-cost materials for RF applications are exposed to rain, snow, sea spray or other moisture, their dielectric performance is undiminished.

“Whether they sit on towers or moving structures – cars, trains, buses and boats, commercial and private aircraft – we are seeing an explosion in the need for installed electronics used for wireless communications,” Dr. Johnson said. “While the vehicles and locations vary, the common thread is that all of those applications are using composites. Our new RF-2200 dielectric series foams and technical expertise equip General Plastics’ customers with the affordable, flexible solutions they need to satisfy their requirements.”

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