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Comparing HDPE and UHMW Polyethylene

Comparing HDPE and UHMW Polyethylene

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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Common Uses of HDPE (High-Density Polyethylene)

Common Uses of HDPE (High-Density Polyethylene)

HDPE or High-Density Polyethylene is part of a widely-used family of thermoplastics, HDPE ‘Polyolefin’, which is produced through polymerizing ethylene and propylene for properties that are excellent in applications such as food handling, food preparation equipment, wear resistance, consumer goods, and much more.

Why this thermoplastic is so popularGlass bottles weigh 16 times more than plastic bottles

HDPE is known for its excellent strength-to-density ratio, as well as its strong intermolecular forces, high impact and tensile strength. These properties combine for a hard, durable plastic that is excellent for many applications from containers for consumer goods to chemical and structural tanks components. At the same time, HDPE is lightweight and highly resistant to stains, odor, moisture, chemicals, and abrasion. Most importantly, HDPE doesn’t contain harsh or toxic chemicals that could be harmful to users, making it excellent for a wide variety of consumer and commercial products. Specifically, HDPE does not contain: BPA, Phthalates, Allergens, Heavy Metals or Harmful fumes.

HDPE has excellent wear and chemical resistance. HDPE is a commonly used material for rub strips, chute liners and bottling plant components. An example of wear resistance is the yellow plastic playground slides which are made of HDPE. This versatile plastic material is often the choice for use for chemical and toxic containers and bottles.

The HDPE material is the common material used to make the one gallon milk jugs. These are easily recycled, and 8 – 10 milk jugs is equal to about one pound of recycled HDPE material. On average, over 115 million milk jugs are recycled each year.

Some common uses of HDPE

HDPE is FDA, USDA, and NSF compliant, making it especially popular for making components such as cutting boards, food preparation surfaces and equipment components. HDPE is often used in a wide range of food processing equipment, food containers and bottles, as well as valve and pump components. However, the Food processing industry isn’t the only industry relying on HDPE. Its excellent impact strength makes this plastic popular for everything from impact parts to dasher boards in ice rinks, to personal protection gear.

In addition, HDPE has excellent properties that make it perfect for heat-formed or vacuum-formed parts, producing food trays and containers and much HDPE can be recycled and made into usable plastic lumbermore. The plastic’s durability and impact resistance makes it an excellent choice for the linings of conventional freezers, bed liners for heavy trucks, and liners in silos. The marine industry is an active user of HDPE due to its toughness and very lightweight to size ratio.

As one of the most used plastics, HDPE has a density of just .941 – .965 per ASTM D792. While many think of Aluminum as a lightweight material, it actually is 2.8 times the weight of  HDPE plastic material.

HDPE also has been successfully used in a variety of cement molds and various types of transfer and storage boards. This plastic can be found in crates and bottles for holding not just food products, but also detergents and cosmetics. Industrial pallet wrapping benefits from HDPE film durability, while petrol tanks benefit from this plastic’s inherent chemical resistance.

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HDPE – LDPE

thick-plastic-sheet

Polyethylene (LDPE, HDPE)

Light-weight FDA grade, Natural and black are standard colors


HDPE and LDPE

High Density Polyethylene (HDPE) and Low Density  Polyethylene (LDPE) are both materials in the Polyolefin family of plastics, along with Polypropylene (PolyPro) and UHMW (Ultra High Molecular Weight).

Manufactured by a variety of manufacturers under several tradenames: Polyboard®, Polymar®, Hostalen®, Polystone®, Hitec® HDPE, Corrtec®, Sanalite®, UltraEthylux®, Polycarve®, and Densetec®.

For great abrasion resistance, very low density, and FDA/NSF compliance, Polyethylene products are an excellent choice.

20"-rod

Why use HDPE/LDPE for your application?

  • Light Weight
  • Stain, Odor, and Moisture Resistant
  • FDA & NSF Approval for Food Contact
  • Vacuum and Thermo-Formable Material
  • Very Durable and Abrasion Resistant
  • Self-lubricating and a low coefficient of friction
  • Very High Chemical Resistance
  • Low Specific Gravity (Floats in Water)
  • Can be Heat Welded or RF Welded
  • High Impact Strength and Energy Absorption
  • Exceptional Low Temperature – Brittle at -110° F
  • Does not chemically bond
  • HDPE/LDPE are ITAR compliant, and HDPE/LDPE are RoHS compliant

Main Differences: 

HDPE – Harder material, little to no flex, better tensile strength
LDPE – Softer, very flexible, lower tensile strength 

 

Applications – HDPE:

  • Cutting Board and Food Preparation Surfaces
  • FDA, USDA, NSF Compliant Machined Parts
  • Heat Formed and Vacuum Formed Parts
  • Dasher Board For Ice Rinks – Impact Parts
  • Welded Tanks, Hoppers, Silo Linings and Slide Chutes
  • Chemical and Structural Tanks and Covers
  • Food Processing Equipment, Valve, and Pump Components

Other applications include cement molds, body boards, transfer boards, death beds, mortician boards, cooler storage boards, spine board, tank liners, wear guides, and many, many more.HDPE is used in thousands of applications, from interiors of freezers, bed liners for trucks to personal protection gear.

HDPE is available in stock in natural (milky white) and black. Other colors are available with minimum runs.

Applications – LDPE:

  • Packaging Applications
  • Industrial bags, produce bags, garment bags
  • Blow Molded Bottles
  • Toys
  • Hot Melt Adhesives
  • Wire Insulation
  • Prosthetic appliances, Medical equipment, Semi-flexible tubing

Extruded Sheet:
.030 – 2.0″ in 48″ X 96″ Smooth Surfaces Natural Sheet in HDPE, 1″ max. for LDPE
Black available in many sizes of HDPE

Film:
.015″ – .060″ in 48″ wide Natural

Rod:
.250″ – 10″ diameter in Natural HDPE – 96″ lengths
From 12″ and up to 30″ diameter in 48″ lengths or 39″ lengths in HDPE

Black is available in many sizes of HDPE

Tube:
.250″ OD – 10″ OD in various wall thicknesses. Most available in HDPE and many in LDPE

Special Formulations:
Conductive, Static Dissipative, Custom sizes, Formulations, Profiles or Colors.

General PropertyASTM
Test
Typical Value HDPETypical Value LDPE
Specific GravityD792.941 – .965.91 – .925
Tensile Strength YieldD6383,800 – 5,5001,400 – 2,000
Izod Impact – NotchedD2562.0 – 3.5>16
Vicat Softening TempD1525257 degrees F219 degrees F
Hardness – RockwellD785D60 -70D42 – 50
Continuous Use Temp-100 – 180 degrees F174 degrees F
Deflection Temp @ 66 psiD648171124
Co. Thermal ExpansionD6967X10-54.6 -5.5X10-5

Playground HDPE is UV stabilized for outdoor applications that is available in a variety of colors.

Sunboard and King StarBoard® are UV stabilized HDPE materials for marine applications.

These properties are for evaluation purposes only. This information is not to be construed as a warranty, guarantee or assurance that you may achieve the same results. Materials made from different resin types, manufacturing techniques and manufacturers will react differently. The information should be used to compare against other materials only, and each user should make his own tests to determine suitability. No warranty as to this materials suitability are either expressed nor implied.

Got Milk… jugs? Now made from HDPE

Got Milk… jugs? Now made from HDPE

Why food safe HDPE plastic replaced glass as the go-to milk container.

Many of you, should you be older than 60, may remember the “Milk Man”. This delivery service from decades ago, was a most common way of transporting milk to the consumer. Back then, suppliers used glass bottles, delivered by this milk man, right to your front door.

HDPE is Food Safe

When looking at alternatives, the milk processing industry found a use and benefit from replacing the glass with a plastic called High Density Polyethylene (HDPE). But what is HDPE, and what are the benefits of using it?

Why HDPE replace Glass Bottles

Glass is heavy, HDPE plastic is light

One of the characteristics of this thermoplastic is the weight of the material. The reason this is so beneficial brings us back to the milk jug. Old style glass milk containers could hold 32 oz., with the empty glass weighing 1.25 lbs. An empty gallon water or milk jug (128 oz.) weighs in at only 0.25 lbs, and holds 4 times more volume. When full, the milk jug can hold more volume than the glass bottle without compromising the strength, especially when being transported. This lowers the overall transport time and significantly reduces the cost of shipping.

This drop in weight and large increase in capacity is why the industry made the switch. The attribute of high durability in plastic materials like HDPE is known as the “strength to weight ratio”. As already mentioned, this was a huge benefit from switching to HDPE containers – the impact it has on transport costs. The high impact resistance of the material allows for easy transport. The HDPE jugs can withstand the jarring and bumping that is a natural part of mass transit, with almost zero wear or breakage to the product. Compared to the glass bottle, too hard of a turn or a pothole in the road could lead to the disheartening sound of shattering glass… not an ideal result for the distributing company. The HDPE impact resistance still holds true through out the supply chain, and even when the containers enter a store or home. If a HDPE milk jug should fall, the plastic container may spill, but it won’t cause the harm or damage that glass would. Broken glass poses a hazard and a risk, whereas plastic in this case can be easily cleaned, recycled, and used again.

When discussing this topic, the argument of recycling and sustainability sets its sights on plastics. In reality, the carbon footprint of plastics is much smaller than that of glass. The amount of heat necessary to heat up plastic for recycling is dramatically lower than that of glass, making it more sustainable in the long run. Yes, both are 100% recyclable, but the amount of fuel necessary plays a big factor. The temperature needed for melting and processing HDPE is between 248 and 356°F depending on grade. Whereas glasHDPE is 100% recycables materials requires a minimum temperature of 2,600°F, according to SeattlePI. As you can see, these temperatures are very different, and shows why the life cycle of plastic is more eco-friendly and a better option to preserve our environment.

Immensely versatile HDPE applications

HDPE has many more uses, like in structural tanks, FDA approved cutting boards and industrial piping systems. This material outweighs most alternatives in benefits due to it’s cost and performance, and is produced in sheet and rod by many major manufacturers in the USA. HDPE plastics are FDA and NSF approved for food applications, making HDPE a food safe product for most food processing and packing applications. For more details on HDPE and it’s benefits see Industrial Plastic Supply or call 866-832-9315

What other applications could benefit from newer and improved materials to make our world safer, cleaner and more efficient?

Co-author: Graham Hess

Are HDPE sheet and Homopolymer Acetal Sheet The Same Materials?

Are HDPE sheet and Homopolymer Acetal Sheet The Same Materials?

Is HDPE Sheet and Acetal Homopolymer Sheet the same?

Here is another popular question asked by our clients. Is HDPE the same as Acetal Copolymer  / Delrin Acetal Homopolymer?
No, they are two totally different materials. Although the natural color of both is a milky white to opaque white, and they do look a bit similar, they are not. (HDPE is milky white to almost translucent depending on thickness, and the Acetal materials are a more opaque white to slightly milky – once again depending on thickness . See picture below of .500″ thick samples of HDPE and Acetal sheets)HDPE compared to Delrin Acetal Homopolymer sheet

HDPE and Acetal – Some Differences

The HDPE sheet and rod is a softer material, and is commonly known for its FDA certification and used in numerous food applications, such as: one gallon milk jugs, cutting boards, colored water glasses/cups, and many, many more. While it can be machined, because it is a bit softer and lighter, the tolerances it can be machined to are not very tight. It is not bondable, so it makes a great non-stick surface for sticky foods and adhesives.


The Acetal Copolymer and the premium Delrin® Acetal Homopolymer also have FDA certification, and are used heavily in the food processing industry. This material is a more mechanical material and is used in bearing and wear applications, cams, feeder screws, etc. This material is can be machined to tight tolerances, and will wear for long periods without lubrication. Due to its exceptional wear properties, it is not bondable, thus requiring mechanical fastening or threads to assemble. It has a very low water absorption, and you will find it in your toilet tank as the white moving parts in the filler mechanism. It is an extremely popular material for machinists, as it works much like soft brass.


While HDPE Sheet and Acetal Sheet look similar, they perform quite a bit differently.

While both materials are FDA approved, are machinable and can be used to make rigid wear resistant parts, they are two different resins and have drastically different physical properties. Another major difference is in the weight of these items, HDPE sheet and rod material weighs about 35% less than the Acetal sheet and rod material. Please check the data sheets for more information to assist in proper material selection. Acetal Data Sheet and HDPE Sheet Data

Acetal is commonly known as: Delrin Homopolymer Acetal, Tecaform AH,Ensital, Unital, Pomalux, Ultraform and many more.

HDPE is also known as: Ultraethylux, Densetec, Polystone G, Fortiflex, Versadur, Hostalen, and many more.

Contact us for more details on the HDPE and Acetal families of plastic materials, e-mail us or call 866-832-9315
Topic: HDPE sheet and Delrin Sheet (Acetal Sheet)