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Plastics 101

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An Overview of HDPE, PET and Polypropylene Packaging

Pioneers in plastics technology

Need help determining what type of plastic solution is best for your brand? Let us help.

Understanding plastics for the blow-molding industry can be very confusing. PET, HDPE and PP have become standard materials in the packaging industry due to their cost, availability, ease of processing, and properties as well as being generally inert and food safe. However, if you are exploring our sustainable packaging solutions, it’s important to keep in mind that not all plastics are created equal, and each one is better suited for certain products and uses versus another. Additionally, the manufacturing process is often tied to specific materials.

Below, you’ll find an overview of some of our most common materials, when they are most often used and their benefits. If you have specific questions on which option is best for your product, please contact one of our experts for help.

Explore Common Plastic Types

Choose the right plastic for your product packaging with help from our experts. We offer plastic packaging solutions for a range of markets, including food, beverage, automotive and home care. Explore the three most common types of plastic, as well as our sustainable options, to see which will bring your product the greatest benefits over its life cycle.

PET Packaging: Clear and Lightweight

PET (polyethylene terephthalate) is a clear, strong and lightweight plastic that is most often used for packaging foods and beverages, thanks to its superior organoleptic properties, which means it has no impact on product flavors. PET also has a superior oxygen barrier when compared to HDPE and PP, making it good for moderately oxygen-sensitive products. Additional barrier materials are needed for highly oxygen-sensitive products. Additionally, PET has extremely good impact properties, making it damage resistant, and it features a superior chemical resistance when compared to HDPE or PP. When compared to other plastic materials, Graham’s PET process results in less design freedom, including the inability to form a true through handle, so it typically requires pinch grip or attached handles.

The main reason to use PET is for its clarity. PET containers are light, damage resistant and easily shapeable, and greatly resemble glass in appearance. Graham’s 2-step process to make PET containers creates more defined neck threads with less variation (i.e. better quality) when compared to extrusion blow molded HDPE/PP containers. PET containers are popular for packaging single-serve beverages, salad dressings, cooking oil, peanut butter, and more. PET is a sustainable option since it is widely recyclable, making it appealing to image conscious sellers and buyers alike.

HDPE Packaging: Economic and Reliable

HDPE is one of the most widely used resin for plastic bottles. It would be selected over PP and PET if clarity, strength, and hot-fill ability were not as important. Graham’s HDPE process allows for more design freedom, including handle options, than PET. It also features a better chemical resistance and impact properties than PP, but not as good as PET.

HDPE is a Type 2 plastic commonly used in making containers for milk, motor oil, detergents, bleaches and more. This material provides a good moisture barrier, making it a great option for moisture-sensitive powder products. Additionally, Graham’s multi-layer HDPE and PP packages with EVOH oxygen barrier have better oxygen barrier than PET by itself. The addition of color makes HDPE opaque, but not glossy. HDPE is highly recyclable. We recycle HDPE bottles at our Graham Recycling Company. The PCR created at the center is used in bottles created at our plant locations.



Polypropylene Packaging: Rigid and Clear

Polypropylene (PP) provides a rigid package with an excellent moisture barrier. One major advantage of PP is its stability at high temperatures, up to 220 °F (104 °C). The compatibility of PP with high filling temperatures is responsible for its use with hot fill and retort fill products. PP, along with HDPE, has many more options for oxygen barrier, handle applications and colors when compared to PET. PP has marginal impact properties, especially at refrigerated temperatures. While PP provides contact clarity, it is not as glass-like in appearance as PET.

PP is often used to make hot-fill juice and tea bottles, as well as retorted packaging for baby formula and adult nutrition products. PP is recyclable, but does not have a widely available recycle stream and instead often gets recycled with HDPE, depending on local regulations.




Post-Consumer Resin: A Sustainable Solution

Post-Consumer Resin (PCR) is the technical term for plastic that was in the market, collected from the consumer and put through the recycling network. The recycled material is cleaned, ground and compounded into uniform pellets. PCR is easily processed. Another type of PCR is Ocean-Bound Plastic. Graham is an expert in incorporating PCR into your plastic containers. For more information on PCR, please visit our Sustainability pages.

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