If your hydraulic equipment is exposed to spikes of high temperatures, industry standard thermoplastic polyurethanes, or TPUs, may fail you.

Today, TPUs are the leading choice for high pressure, dynamic sealing applications. Their resiliency, thermal stability, wear resistance and high bond strength have made them an industry standard for high performance sealing systems. However, at very high temperatures these thermoplastic seals can melt or warp, causing failure of the sealing system and costly equipment downtime.


Parker’s Resilon series of high-temperature polyurethane seals is designed with a proprietary formula that provides extended seal life for applications exposed to extreme temperatures. Resilon uses a PPDI polymer backbone to provide superior heat resistance, compression set resistance and rebound/resilience for the best commercially available over-all sealing performance on the market. PPDI possesses characteristics that allow it to have a low internal heat build-up and higher softening temperature when compared to other thermoplastic polymers of its class.

Parker recently introduced Resilon 4350, a new polyurethane material for sealing systems that can withstand an operating temperature of up to 250°F, an increase of 20° from Resilion 4300. Resilon 4350 is engineered with high temperature nanotechnology that prevents polymer degradation and gives it dynamic properties for superior performance. These qualities included an increase of 30% in sealing force up to the highest operating temperatures and an ability to withstand temperature spikes of up to 300°F.


Resilion 4350 provides an extended seal life for all applications and temperatures. This critical advantage saves both time and money that would be spent repairing failed sealing systems. In tests that compared the 4350 series to leading competitors at an operating temperature of 250°F, Parker’s Resilon lasted for 20% longer before a leak was detected. Perhaps even more critically, even once the Resilon 4350 did experience a failure, the high sealing force minimized leaking as the test continued.


The Resilon 4350 is offered in Parker Preferred Profiles for Fluid Power Seals or custom designed profiles. Seals can be either molded or machined.

Resilion Physical Properties:

  4350A90 4300A90
Hardness, Shore A, pts 90 90
Modulus @ 100%, psi (MPa)





Ultimate Tensile Strength, psi (MPa)





Elongation, % 570 638
Specific Gravity 1.18 1.17
Rebound, % 62 61
Compression Set, %, 70 gr @ 212°F 26.3 30.9
Tg, DSC, °C -44.1 -41.6

The Resilon 4350 series is specifically suited for injection molding applications but is also recommended for a variety of other applications, including the piston seals, rod seals, wipers and O-Rings for many types of hydraulic cylinders and shock absorbers used on off-road, industrial and construction equipment. If your sealing system is failing when exposed to high temperatures, it is time to switch to Resilon 4350 seals and and reduce the occurrence of costly downtime.


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