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 popular
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 notcontain: 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 more. 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.
Looking for a supplier of polyethylene thermoplastics?
Industrial Plastic Supply, Inc. is an expert in performance plastics, and has one of the largest material inventories in the World. To learn more, check out full line Performance Plastic materials on our website.
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?
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 glass 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?
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:
General Property
ASTM Test
Typical Value HDPE
Typical Value LDPE
Typical Value UHMW
Specific Gravity
D792
.941 – .965
.91 – .925
.93 – .94
Tensile Strength Yield
D638
3,800 – 5,500
1,400 – 2,000
6,800
Izod Impact – Notched
D256
2.0 – 3.5
>16
No Break
Vicat Softening Temp
D1525
257ºF
219ºF
260
Hardness – Rockwell
D785
D60 -70
D42 – 50
R64
Continuous Use Temp
–
-100 – 180ºF
174ºF
180ºF
Deflection Temp @ 66 psi
D648
171
124
174
Co. Thermal Expansion
D696
7X10-5
4.6 -5.5X10-5
11.0X10-5
Please contact us for more information on FDA and NSF approved plastic materials. Email us here, or call us at: 866-832-9315
This question was very easy to answer, up until now.
First: what is Zytel 42? It is a Natural Nylon 6/6 extrusion grade plastic resin. An extremely popular and heavily used material for machinable and durable plastic parts. For as far back as we can find information, this Zytel 42 Nylon 6/6 resin has been used in numerous food contact and food processing machine components.
We have just received notice that Dupont will be making some changes to their formula for this Nylon grade. For years we have provided our clients with Dupont Zytel 42 Nylon resin extruded into sheet, rod and other profiles. The Dupont announcement states that the Zytel 42 will no longer have a food grade rating – FDA approval. They will produce a new resin called Zytel 42FG, which will have all the approvals we always had with the Zytel 42.
Why in the world would a company do such a thing? Our guess is that this is a cleaver way to increase prices significantly without a standard and blatant price increase. Let’s just hide it in a new resin package.
Zytel 42 – will still be available, but without the FDA approval
Zytel 42FG – the ‘new’ resin will carry the FDA approval, but at much higher price
Nylon Food Grade still available
These huge Cast Nylon Blocks 12″ X 12″ X 48″
What is the difference between the old Zytel 42 and the new Zytel 42FG? From what we have read so far, nothing. It is probably the same material, new name. The ‘new’ Zytel 42 is actually the new ‘dumbed’ down resin – they just took away the Food Grade label, maybe took out an ingredient or two, and viola, new Zytel 42 – non Food Grade Nylon.
This news has spread quickly through our industry. As mentioned above, we have provided this material in this grade for over 36 years for Food Grade/FDA Approved applications.
The main reason for this article is to get the news out the the marketplace. Engineers and designers have been specifying this resin for their applications, and now, with out much notice, the product they assume is Food Grade will no longer be acceptable for these applications. It is unclear at this point whether the extrusion plants will be producing product from both resins, or opting to use one or the other. It appears that Nylon Food Grade resins my become a special, or that all materials may becomes standard as Nylon Food Grade.
Is Nylon Food Grade Resin Important To You?
This is the question we find ourselves asking. Does the end user think of Nylon when they are looking for an FDA approved plastic? Or, do they consider Acetal Copolymer, Acetal Homopolymer, Polyethylene, and other materials first? Do you think of Nylon rod, bar, sheet and slab as mechanical materials to use when making gears, wear strips, and other non FDA applications?
Please take a moment and let us know you thoughts. We value your input – it will help us in evaluating the direction we want to go with our inventory.
