UHMWPE - the unknown polymer

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One of the few good things to happen due to the unprecedented escalation of PTFE prices globally was that it allowed us to look at alternate materials and seriously gauge the feasibility of manufacturing them.

In an earlier post, we looked at the various properties of PTFE and compared them to the other polymers. And although the key takeaway from that exercise was that PTFE was an immensely versatile material which was difficult to replace, we did make mention of possible alternatives, provided the user was willing to compromise on some parameters.

A key polymer which struck us then and continues to feature prominently in our product offering today is UHMWPE. We would like to take a more detailed look at UHMWPE for two reasons:

1. It does measure up against PTFE as a low-cost substitute (with certain limitations)
2. It&#;s properties do not seem to be as widely known to end-users, resulting in a limited use in many applications where it would otherwise be ideal

 What is UHMWPE?

Sometimes referred to as just &#;UHMW&#;, UHMWPE or Ultra High Molecular Weight Poly Ethylene is an off-white polymer that exhibits superior strength while being both light-weight and possessing a low coefficient of friction.

While it is not entirely accurate to refer to it as an &#;unknown&#; polymer &#; our own analysis of search terms within Google tells us that a total of ~62,000 searches per month are done globally for UHMWPE and/or UHMW. This is tiny in comparison to searches for PTFE/Teflon (1,300,000 per month) or for Nylon (5,500,000 per month).

Comparison with PTFE

So how does UHMWPE compare with PTFE? In our own opinion &#; it compares rather well. In fact, if you take all the applications involving PTFE and remove the ones that call for heat resistance, UHMWPE is a very workable substitute.

Although a full comparison chart is given at the end of this article, we would like to look at some specific properties more subjectively.

1. Temperature resistance: Let&#;s get this one out of the way, since we know that it is UHMWPE&#;s weakness. Having an operating temperature of only about 80°C compared with 260°C for PTFE, UHMWPE is automatically disqualified in a range of industrial applications where the temperatures surrounding the material are expected to be well in excess of it&#;s upper limit.
2. Wear resistance: Before we were familiar with UHMWPE, we were asked to advice a cement plant on whether they could use Lubring sheets (PTFE+Bronze) in a wear application. We were confident that it would work and when they mentioned that they had tried UHMWPE and it had failed, we did not think it was worth looking into. But when we did compare the materials, we realized that if UHMWPE had failed, there was little chance PTFE would work &#; since the gap between the two materials on this parameter is quite wide.Keep in mind that PTFE+Bronze is the most wear resistance grade of PTFE available. So if we compare UHMWPE with plain PTFE, the rift is even wider.
3. Coefficient of friction: It is difficult to beat PTFE on this parameter, although UHMWPE comes fairly close. While it remains true that the coefficient of friction between PTFE and polished stainless steel is the lowest between two known solids (0.03-0.05), UHMWPE is able to reach a somewhat respectable 0.1-0.15 on this metric. While this does put it out of range for many applications where the recommended coefficient cannot exceed 0.1 (eg: sliding bearings) &#; it is a useful substitute in components where smooth movement between parts is the only requirement.
4. Dielectric strength: Both materials are pretty much neck and neck on dielectric strength. Where UHMWPE loses out is on its ability to be skived into thin tapes. While we regularly skive PTFE down to 0.04-0.05mm thicknesses, the same is more challenging with UHMWPE, since it lends a much higher wear on to the skiving blade, making it difficult to achieve long lengths of tape before the blade dulls out and breaks the tape. Nonetheless, thicknesses of 0.1mm and above are more than feasible, meaning that as an insulating pad or even a component used in high voltage applications, UHMWPE is more than suitable.
5. Chemical inertness: PTFE is well known for it&#;s inertness and this allows it to lend itself to applications ranging from biotechnology to medical devices and chemical linings. While UHMWPE does not have quite the same extreme inertness as PTFE, it does find use in medical applications (it is used in parts for joint replacements) and can easily be used in both biotech and chemical applications, provided the exact nature of chemicals is known and compared against it&#;s capabilities.
6. Weight: While weight has never been a consideration for PTFE in any of it&#;s applications, we would still like to highlight that UHMWPE is less than half the weight of PTFE (specific gravity of 0.95 vs. 2.15 for PTFE). The key difference this adds is in their respective cost cacluations. Not only is UHMWPE cheaper in resin form (roughly 1/4th the cost per Kg), but the fact that you consume only half the weight to get the same volume of finished product implies that the effective cost is 1/8th the cost of PTFE. This represents a significant saving.

So where can we use UHMWPE?

There are a range of applications where UHMWPE could and should be used. In many cases, we have tried to suggest to the end-user that we can offer them UHMWPE in stead of PTFE, but due to restrictions on standards and because changing specifications can be time consuming, very few have opted for the change.

Strangely, in many cases, clients have opted for suppliers offering reprocessed PTFE, but not UHMWPE. Given the highly diminished properties of reprocessed PTFE, this is functionally not a great trade-off in the medium to long term.

1. Automotives: Most automotive applications use PTFE in high temperature environments, so UHMWPE does not fit the requirement. However, there are a number of applications where the parts operate at room temperature eg: car doors, seats, hand levers etc. and here UHMWPE can find a lot of use. We are aware that the wear strip used inside car doors employs UHMWPE. In general, UHMWPE wear strips offer a low cost and effective alternative to PTFE wear strips.
2. Valves and seals: Typically, valves and seals require a low coefficient of friction with a good wear resistance.  UHMWPE is an excellent replacement for PTFE in these areas.
3. Medical: UHMWPE is widely used in joint replacements due to its chemical inertness and light-weight.
4. Infrastructure: Although regulatory restrictions prevent materials other than PTFE to be used POT bearings, there are many sliding bearing applications which do not fall under the government codes and are therefore potential areas where UHMWPE can be used. UHMWPE could be employed successfully in sliding bearings and as plain sliding pads.
5. Electronics: Many components used in electronics have traditionally employed PTFE components for insulation. In a number of cases, we have successfully tested UHMWPE for these applications and convinced the client to shift.

Overall, there continues to be a resistance to employ a material like UHMWPE. Part of this is regulatory &#; drawings and specifications that call for PTFE cannot be changed over night. But mostly there is a genuine dearth of awareness about the material &#; which is equally difficult to change. While it is true that UHMWPE is a substitute for PTFE &#; we see it as more of a partner in application &#; allowing many end-users to find a competitive, low-cost solution where they would otherwise be unable to proceed with their development or manufacturing.

Comparison chart between PTFE and UHMWPE

  UHMWPE PTFE Units Colour Off-white White   Specific Gravity, 73°F 0.944 2.25   Tensile Strength @ Yield, 73°F psi Tensile Modulus of Elasticity, 73°F 155,900 150,000 psi Tensile Elongation (at break), 73°F 330 350 % Flexural Modulus of Elasticity 107,900 145,000 psi Compressive Strength at 2% deformation 400 psi Compressive Strength 10% Deformation psi Deformation Under Load 6-8% 2.5-5% % Compressive Modulus of Elasticity, 73°F 69,650 79,750 psi Hardness, Durometer (Shore &#;D&#; scale) 69 55-65   Izod Impact, Notched @ 73°F 30 161 ft.lbs./in. of notch Coefficient of Friction (Dry vs Steel) Static 0.17 .06-0.12   Coefficient of Friction (Dry vs Steel) Dynamic 0.14 0.12   Sand Wheel Wear/Abrasion Test 95 90 UHMW=100 Coefficient of Linear Thermal Expansion 11 6-7.2 in/in/°F x 10-5 Melting Point (Crystalline Peak) 135-145 380 °C Maximum Service Temperature 80 260 °C Volume Resistivity > NA ohm-cm Surface Resistivity > NA ohm-cm Water Absorption, Immersion 24 Hours Nil Nil % Water Absorption, Immersion Saturation Nil Nil % Machine-ability Rating 5 3 1 = easy, 10 = difficult

At a glance

• Explore the diverse uses of UHMWPE across industries, from food processing to automotive innovations.
• Discover why UHMWPE is renowned for its durability, chemical resistance, and low friction coefficient.
• Consider ePOL for purchasing UHMWPE, offering competitive prices, live online pricing, and worry-free nationwide delivery.

 

 

In the realm of engineering plastics, one material stands out for its exceptional properties and versatility: Ultra-High Molecular Weight Polyethylene (UHMWPE).

This premium-class material, notably offered by Okulen®, combines outstanding abrasion resistance, minimal water absorption, and excellent chemical resistance with superior wear resistance, high impact strength, and phenomenal sliding properties.

However, it's essential to note that UHMWPE is not suited for high-temperature applications.

This guide delves into the most common applications of UHMWPE, shedding light on why it is a preferred choice in various industries.

 

What is UHMWPE?

 

First and foremost, let's understand what UHMWPE is.

UHMWPE plastic is characterised by its ultra-high molecular weight. It is a low-pressure polyethylene with a molecular structure that provides unparalleled durability and performance characteristics.

It comes in various forms, including rods and sheets, and is FDA-compliant, making it safe for use in medical and food processing applications.

 

Key Applications of UHMWPE

 

Food Processing Industry

In the food processing sector, UHMWPE shines due to its non-toxic nature and FDA compliance. It is used in the manufacturing of bearings, gears, chute liners, and wear strips.

These components benefit from UHMWPE's low friction and non-stick properties, ensuring smooth operations and easy maintenance.

 

Material Handling and Packaging

The material handling and packaging industries greatly benefit from UHMWPE's durability and resistance to wear.

Anti-static chute liners, wear strips, bearings, and gears made from UHMWPE sheet Australia enhance equipment longevity and efficiency, significantly reducing downtime due to maintenance.

 

Conveyor Systems

UHMWPE's excellent sliding properties make it ideal for conveyor system components such as wear strips, gears, and chain guides.

Its ability to withstand continuous movement and friction ensures reliable operation in various settings, from manufacturing plants to distribution centres.

 

Marine Applications

The marine environment demands materials that can resist water, salt, and constant wear. UHMWPE meets these requirements perfectly, used in covers, doors, fixtures, dock fenders, boat components and handles.

Its low moisture absorption and corrosion resistance make it an excellent choice for marine applications. UHMWPE ideal for both structural and aesthetic marine applications.

 

Waste Water Treatment Facilities

Durability and chemical resistance are crucial in waste water treatment facilities. UHMWPE components like wear strips, paddles, bearings, scraper blades, and chute liners offer unmatched performance. It is capable of withstanding harsh chemicals and abrasive materials. 

 

If you are looking for more details, kindly visit UHMWPE Plant.

Infrastructure and Construction

In the realm of infrastructure, UHMWPE's impact resistance and durability make it an excellent choice. It is ideal for creating components like sliding pads and bearings that require low maintenance and offer long service lives.

UHMWPE strips are particularly valued for their ease of installation and ability to withstand heavy loads, making them ideal for various construction applications.

 

Automotive Industry Innovations

While UHMWPE may not be the first choice for high-temperature automotive applications, its strengths lie in areas requiring durability at room temperature.

Components such as door panels, seating mechanisms, and various interior parts benefit from UHMWPE's wear resistance and strength, offering a lightweight, durable alternative to traditional materials.

 

Advanced Protective Gear

The high impact strength and lightweight nature of UHMWPE make it suitable for personal protective equipment, such as body armour.

Its ability to absorb and disperse energy efficiently makes it a critical material for protective gear, offering both safety and comfort to the wearer.

 

Sporting and Leisure Applications

UHMWPE's durability and resistance to wear extend to the sports and leisure industry. It is used in the production of components for recreational vehicles, such as snowmobiles and ATVs, enhancing performance and reliability.

 

Additional Industrial Uses

Beyond these specific applications, UHMWPE finds utility in a myriad of industrial settings, including but not limited to:

 

Bed Liners:

UHMWPE bed liners for trucks and containers offer exceptional durability and non-stick properties, ensuring easy loading and unloading of materials.

 

Plastic Rods and Sheets:

Available in rods and sheets, UHMWPE is easy to fabricate into custom shapes and sizes for a vast range of applications, from gears and bearings to custom machine parts.

 

 

 

Performance Characteristics of UHMWPE

 

UHMWPE is renowned for its toughness and durability, with a high impact strength that makes it resistant to cracking and breaking under stress.

Its low friction coefficient enhances its wear resistance and imparts excellent sliding properties. This makes it the go-to material for applications requiring smooth and efficient movement.

Moreover, UHMWPE's good chemical resistance ensures  that it can withstand exposure to a wide range of substances, making it suitable for use in environments where chemical contact is inevitable.

Its low moisture absorption is another critical feature, ensuring stability and longevity in wet conditions.

Fabrication is straightforward with UHMWPE, allowing for the creation of custom parts and components to meet specific application requirements.

Whether it's UHMWPE strips or sheets, the material can be machined and welded to create precisely what's needed.

 

Conclusion

In conclusion, UHMWPE stands as a material of choice across various industries, offering a unique combination of strength, durability, and resistance to chemicals and water.

Whether you're considering UHMWPE for new applications or as a replacement for less capable materials, its benefits are clear.

For those exploring options, UHMWPE strips and sheets provided by companies like Okulen® offer a promising solution that meets stringent performance and safety standards.

If you're interested in purchasing UHMWPE material, consider buying from ePOL.

With ePOL, you can easily order engineering plastics in sheet and rod at competitive prices, with live online pricing and inventory.

Plus, enjoy worry-free deliveries with free shipping on orders over $150 nationwide. Experience the ePOL difference today and register online to discover why ePOL is arguably Australia&#;s best engineering plastics supplier.

 

Frequently Asked Questions

 

Is UHMWPE strong?

Absolutely. UHMWPE is recognised for its exceptional toughness and high-impact strength, making it capable of enduring severe conditions without failure.

 

Is UHMWPE recyclable?

Yes, UHMWPE is recyclable, aligning with sustainability goals and reducing the environmental impact of industrial processes.

 

Is UHMWPE non-stick?

Indeed, UHMWPE boasts excellent non-stick properties and sliding ability, ideal for applications like truck and container liners where material adherence can be a problem.

 

Is UHMWPE toxic?

No, UHMWPE is non-toxic and non-hazardous, making it safe for use in medical applications and food processing.

 

Does UHMWPE absorb water?

No, it has zero water absorption levels, ensuring its performance is not compromised in wet or humid environments.

 

Contact us to discuss your requirements of MMA Plant. Our experienced sales team can help you identify the options that best suit your needs.