HDPE vs UHMW: When to Use High-Density Polyethylene
HDPE and UHMW are popular and well known types of plastics across many different industries for their reliability, so much so that many people have started to use them interchangeably. However, their uses don’t coin cide nearly as often as many think–HDPE has different qualities that lend well to different applications. While both materials are very light, with a density of .94 – which means they both float in water.
When best to use HDPE
High-Density Polyethylene or HDPE is known for its versatility and low moisture absorption, which result from its high-density chemical makeup. Its chemical composition also makes it highly chemical resistant, so it’s excellent for applications that involve moisture or mild chemicals.
HDPE is also very easy to machine and shape. As a result, it has been used successfully to make plastic lumber, milk jugs, containers, cutting boards, and many other products.
In addition to being easy to machine, HDPE sheet and rod are also relatively lightweight, and can be NSF and FDA compliant. This very durable material can not be glued or bonded, and thus must be heat welded together or attached with mechanical fasteners. HDPE is excellent for applications where reduced weight and low costs are paramount. This, combined with its easy machinability, allows HDPE to be cut, drilled, routed and shaped for many different end uses. Food cutting boards, piping, storage vessels, marine components, and many more benefit from HDPE. It’s also been successful in outdoor furniture, signage, playground equipment, structural tanks, food processing equipment, vacuum-formed parts, transfer boards, tank liners–and this is just a small number of its applications.
When not to use HDPE
While HDPE and UHMW have similar properties, they are often better suited to different tasks. Both plastics do have high impact resistance, but UHMW (Ultra-High Molecular Weight Polyethylene) performs better in applications where friction and constant impact are present. The UHMW molecular chain is much longer, thus giving UHMW the extreme wear resistance. This results in UHMW being used more often in functional components, like conveyor systems, concrete chute liners, mated parts, bumpers, and bearing applications. HDPE does not perform as well as UHMW under constant friction, making HDPE better for food processing surfaces, chemical resistant parts, decorative products, or components that will not experience constant friction. If a reduced friction application is needed, the use of UHMW with a coefficient of friction of just 0.08 (compared to HDPE with a coefficient of friction of 0.20) is much more suitable.
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Next time you are cutting vegetables on your cutting board, the material most likely to be used is Polyethylene. Because it is stain, moisture and odor resistant, Polyethylene is a perfect choice. Other cutting boards made out of wood are more susceptible to bacteria and odors because they lack the properties that Polyethylene sheets offer, such as its chemical resistance and FDA approval for food contact. Polyethylene is a very durable and lightweight material that comes in many forms and is a great for a wide variety of applications.
NSF Approved Cutting Boards
The HDPE is available in .500″ thick in several FDA / NSF approved colors, and is great for use in kitchens where cross contamination is a problem.
The Ultimate Cutting Board
Polyethylene has many names. The most common are HDPE, LDPE, and UHMW. The difference has to with the molecular weight and branching which is when a monomer or atom is replaced by a longer chain of polymers (a long repeating chain of atoms). High Density is commonly used for milk jugs and food containers. Low Density is commonly used for bottles and plastic bags. UHMW, which has higher molecular weight (2-6 million) allows for an even transfer over the length of material which makes it stronger and able to be used for bearing applications due to its great wear resistance. Commonly used in the food and dairy industry, UHMW is a great replacement for other materials and solution to many problems. All of these polymers are derived from the same family but all have certain properties that make them a little different. HDPE provides great chemical resistance, with high impact strength and great energy absorption. LDPE has most of the same properties as High Density but is not as dense at 9.15, opposed to HDPE which is 9.34. It also has a lower tensile strength and easier formability.
UHMW is a strong material that has great durability and low co-efficient making it an ideal for sliding applications. Polyethylene offers a wide range of material choices and properties and has great durability that can be suitable for a number of applications. From the food industry to automotive, the kitchen or the warehouse, whatever your Polyethylene needs are; High Density, Low Density or UHMW, Polyethylene is a great choice.
Typical Resin Properties:
Typical Value HDPE
Typical Value LDPE
Typical Value UHMW
.941 – .965
.91 – .925
.93 – .94
Tensile Strength Yield
3,800 – 5,500
1,400 – 2,000
Izod Impact – Notched
2.0 – 3.5
Vicat Softening Temp
Hardness – Rockwell
D42 – 50
Continuous Use Temp
-100 – 180ºF
Deflection Temp @ 66 psi
Co. Thermal Expansion
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