HDPE vs PET – Which One Should I Pick?
High-Density Polyethylene (HDPE) and Polyethylene Terephthalate (PET) are two types of commonly used plastics made for everyday use – from packaging to food storage, and containers for pharmaceutical products.
However, if one type of plastic is good for these purposes, why are both types commonly used?
This article will attempt to explain and outline the difference between HDPE and PET, their specific uses and why both products are required in equal measure.
What Is Polyethylene Terephthalate? (PET)
Polyethylene Terephthalate (PET) is a thermoplastic polymer belonging to the polyester family. Thermoplastics liquidize at high temperatures and harden on cooling which creates a more rigid plastic material with a higher tensile strength.
PET is commonly used in the production of plastic bottles, food containers and packaging films. It’s also used in the pharmaceutical industry for medicine bottles, pill packaging, vials, inhalers and diagnostic test kits.
The Main Physical Properties of PET Include:
- Recyclability: PET plastic is highly recyclable, making it sought after for use in disposable products – as manufacturers and consumers have the peace of mind that any waste doesn’t pollute the environment or end up in landfill.
- Clarity: PET plastic is naturally transparent, letting customers see what they’re getting before they buy.
- Strength: PET is a strong, rigid material – making it effective at protecting the product from damage during transit or handling.
- Lightweight: PET is relatively lightweight — making it a cost-effective material for transport. For example, PET is the plastic of choice for medicine bottles as it helps reduce weight and shipping costs.
- Barrier Properties: PET is an excellent barrier against moisture, gas and UV light. This makes it an essential material for protecting products from anything that might affect the chemical makeup of the product.
- Chemical Resistance: PET plastic has an enhanced resistance to many types of corrosive chemicals. This makes it the perfect plastic for storing reactive or potentially volatile compounds without weakening the packaging.
- Thermal Stability: PET can withstand a range of temperatures during processing, storage and transportation — making it versatile enough to protect a range of products.
PET plastic is a must-have for any business dealing with the storage and transportation of delicate products. In the pharmaceutical industry, that need is larger than ever. Origin offers affordable, high-quality PET Bottles that can be used for a wide range of pharmaceutical products.
What is High-Density Polyethene? (HDPE)
High-Density Polyethylene (HDPE) is another highly versatile thermoplastic known for its versatility for packaging and its protective qualities. HDPE is made using petroleum and formed through the process of polymerization.
It is commonly used in plastic packaging and protective materials — like plastic bottles and pipes. However, it’s also commonly used within the pharmaceuticals industry for packaging, medicine bottles, caps and closures, labware, pill bottles, prescription packaging and inhaler components.
HDPE has a high-density, linear structure that results in a rigid and tough material. However, Low-Density Polyethylene (LDPE) retains much of the tensile strength of its high-density counterpart – but is much less rigid in design. LDPE is commonly used for a more flexible form of protection like plastic bags or pharmaceutical IV bags.
The Main Physical Properties of HDPE Include:
- Density: HDPE has a high density, ranging from 0.941 to 0.965 g/cm³. This high density contributes to its strength and rigidity.
- Strength & Stiffness: HDPE can withstand high compression forces without deforming, bending or shattering — making it the perfect material to safeguard delicate products during transit and delivery.
- Impact Resistance: Because of how strong HDPE plastic is, it can effectively absorb the energy generated from sudden impacts and protect the goods inside.
- Flexibility: Despite its rigidity, HDPE is relatively flexible, allowing packaging made from it to bend and deform slightly without breaking. This makes HDPE useful for bespoke packaging solutions where flexibility is required just as much as strength.
- Chemical Resistance: HDPE has a high chemical resistance. This makes it an essential material for storing delicate pharmaceutical products that may corrode other types of polymers.
- Moisture Resistance: HDPE is non-permeable, meaning it doesn’t let moisture get into or near products. This can extend the shelf life of pharmaceutical products and protect them against rapid decomposition.
- UV Resistance: HDPE can protect stored products against high amounts of UV radiation. This prevents pharmaceutical liquids and other products having their chemistry altered by the sun.
HDPE plastic is essential for any business looking for a dense and rigid packaging material with a high tensile strength. Origin offers a range of HDPE bottles at a competitive price. These HDPE bottles can be used for storing delicate medicines – providing strong barrier protection against sunlight, moisture and heat.
Sustainability and Recycling Benefits of HDPE and PET
HDPE and PET offer similar sustainability and recycling benefits. Both products are highly recyclable and can even be repurposed to create new products out of recycled materials.
Recycling HDPE and PET reduces the demand for virgin plastic, conserves resources and reduces landfill waste.
Additionally, the recycling process for HDPE and PET has a lower energy consumption than many other forms of plastic recycling or virgin plastic production.
Because both plastics can be recycled and repurposed in a way that benefits the environment and a business’s bottom line, many of them are choosing these materials as they promote a more responsible and sustainable approach to plastic production.
Common Uses of HDPE and PET
Both types of plastic are highly versatile and find use across many industries because of their protective properties.
Beyond the pharmaceutical industry, HDPE is commonly used to manufacture bottles and containers, pipes and fittings, construction materials and automotive parts.
PET is commonly used in beverage bottles, food packaging (as it’s considered food-safe by the FSA), textiles, personal care products and electrical insulation.
Is PET or HDPE Better for Pharmaceutical Packaging?
Both PET and HDPE have their uses in pharmaceutical packaging. PET is transparent, non-permeable, and chemical resistant. This makes it more suitable for liquid medications and volatile or harsh chemicals.
HDPE on the other hand, is much more durable, more impact resistant and does not corrode when storing most common pharmaceutical liquids.
The choice between PET and HDPE plastics will ultimately depend on what products you’re trying to package. For example, formulas in glass pipette bottles may need a more durable HDPE secondary packaging to protect the delicate glass from impacts, whereas other products, like pill trays, don’t require that level of durability.
Frequently Asked Questions (FAQs)
Are HDPE and PET Waterproof?
HDPE is known for its impermeability — making it suitable for everything from packaging and containers, to pipes and outdoor furniture that are constantly exposed to the elements.
PET’s water-resistant properties mean that it can be used in the manufacture of water bottles, food containers and other liquid storage applications.
What is the Melting Point of HDPE and PET?
The melting point of HDPE (High-Density Polyethylene) typically ranges from 120 – 180°C (248 – 356°F) depending on the specific grade of HDPE and its chemical composition. PET (Polyethylene Terephthalate) has a higher melting point, ranging from 240 – 260°C (464 – 500°F).
Are HDPE and PET Expensive?
HDPE is considered a relatively inexpensive plastic when compared to other plastics of similar composition and usage types. PET plastic is also available at a more modest price range, with HDPE being slightly more cost-effective on average. However, when compared to other plastics, HDPE and PET are both considered highly cost-effective.
Can HDPE and PET be Mixed?
HDPE and PET are two distinct types of plastic with unique chemical compositions and physical properties – this means that they’re not compatible to be mixed together. Attempting to mix HDPE and PET would result in a structurally unstable, incompatible blend. It’s possible to separate HDPE and PET plastics used in the same product to improve recycling, but it requires the use of two separate recycling methods upon disposal — making the finished product difficult to recycle.
How Strong are HDPE and PET?
Both HDPE and PET have good strength properties – although the specific strength characteristics differ. HDPE is known for its higher tensile strength and impact resistance. This makes it better suited for containers and products that are likely to undergo sudden impacts.
PET is still strong but not as rigid. Because of this, it’s more flexible and can be more easily moulded into bespoke shapes to achieve a unique design — something that’s difficult to do with rigid HDPE plastic.
