Amid evolving regulations and emerging guidelines for the development of recyclable plastic packaging, many ask: "Is PET recyclable?" This question has become increasingly significant following recent adjustments to the recycling guidelines for PET.
Polyethylene terephthalate (PET) is the most common material used in the production of rigid plastic packaging, accounting for approximately 36.8% of 2023 consumption according to the Smithers report “The Future of Rigid Plastic Packaging to 2028.” While PET is used in a wide range of food, medical, and consumer goods applications, the primary end-use application is beverage bottles.
Identified by the Resin ID Code (RIC) #1, PET bottles, and jars are accepted by virtually all recycling programs in the US & Canada. The 2022 PET Recycling Report from the National Association for PET Container Resources (NAPCOR) found that PET recycling rates were at 29% in the US and 37.8% in North America. Considering the high-volume of clear PET used in the bottle industry, there is a robust recycling stream for post-consumer recycled (PCR) PET from recycled bottles, with nearly 2 billion pounds of PET bottles collected for recycling in 2018, and the demand for recycled PET (rPET) is strong.
But the recyclability of PET thermoforms is not so straight-forward. According to a 2020 study conducted by resource recycling, there is an estimated 1.6 billion lbs of PET thermoforms in circulation in the US and Canada. However, while PET thermoform packaging, including items such as clamshells, cups, tubs, lids, trays, egg cartons, and similar rigid, non-bottle packaging is technically recyclable, only 9% of these items are reportedly recycled.
So, the question remains, is PET recyclable? Continue reading to hear the ICPG experts weigh in on the nuances of PET recyclability:
What are the Different Types of PET Used in Rigid Packaging?
There are several different grades of PET used in different types of rigid packaging applications:
- Bottle Grade: Used in the conversion of injection molded pre-forms and blow molded bottles where there is a requirement for high transparency;
- Amorphous PET (APET): Used in the production of sheet & rollstock for thermoformed containers, valued for its good optical properties, mechanical strength and excellent barrier properties;
- Crystalline PET (CPET): Has a partially crystalline structure which offers stability at higher temperatures. This grade is generally produced in black and is used to manufacture sheet/rollstock for thermoformed containers for high-heat applications including dual-oven able (Oven up to 4000F for up to 30 mins) and microwavable applications.
- Glycol-modified PET (PETG): A high-clarity co-polyester with high stiffness and good impact strength commonly used in medical thermoformed applications;
- Recycled PET (rPET): Post-consumer or post-industrial recycled material commonly added to virgin PET to increase recycled content of the package.
There are grades of bio-based PET materials under development.
What are the Benefits of Using PET in Rigid Thermoformed Packaging?
PET provides several positive attributes for rigid thermoformed packaging including:
- High clarity: often referred to as “Water Clarity” and has set the standard for clear rigid packing for both contact and non-contact products;
- Rigidity: Enables down gauging;
- Top-load: high stiffness material which provides good top load or crush strength;
- Formability: Forms well on traditional thermoforming equipment without the need for higher heat requirements of alternate materials;
- Natural barrier: suitable for mid to short shelf-life and refrigerated products.
Is All PET Recyclable?
While PET bottles are widely recycled, and PET is generally considered a recyclable material, not all PET packaging is currently recyclable at-scale. Differences in color, intrinsic viscosity (IV) and material content may affect the ability to be successfully sorted and collected for recycling.
For example, the US Plastics Pact has listed opaque PET on their list of Problematic & Unnecessary Materials because the pigments used in the opaque colored products leave the resulting recycled plastic stained, limiting the materials’ use in future products and contaminating the valuable clear PET recycling stream. The APR design guide also states that each modification to the base clear PET must be considered for its potential effect on the recycling stream.
Additionally, while PETG is part of the same material “family,” this grade of PET is not considered recyclable with other RIC #1 materials because it is glycol-modified. This modification changes the plastics’ melting temperature, which makes it more difficult to recycle along with regular PET and can contaminate the recycling stream and even damage recycling machinery.
Why are PET Thermoforms Recycled Less Frequently than PET Bottles?
There are several factors including the ability to sort thermoforms and the potential risk of contaminating the recycled bottle stream. Generally, PET used in the production of PET bottles have similar material requirements but can range in thickness given the target application (ex. hot fill vs. ambient fill).
However, the variability that can exist in material composition among PET thermoforms such as variations in color, IV and material content can make it difficult. Sorting/recycling systems would need to be able to identify the differences between APET, PETG and CPET, colors and laminations to successfully sort and collect thermoforms.
For example, PET structures can be modified for enhanced properties such as multi-layer film lamination, opaque PET (commonly black, blue, green etc.), optical brighteners, those produced with other oxygen barriers or scavengers, or any other elements considered detrimental to recycling. Since these elements cannot be removed or separated from the base resin for recycling, they have the potential to be detrimental to recycling and contaminate the recycled PET bottle stream.
How Does Intrinsic Viscosity (IV) Impact Extrusion and Thermoforming?
Intrinsic Viscosity, or IV, is a measurement of the PET material’s melting point, crystallinity, and tensile strength and is a key characteristic of PET.
Processing low or unknown IV grade PET in thermoforming can lead to undesired effects, such as variation in extrusion pressure and melt viscosity, which could lead to sheet thickness variation or brittleness. Should the IV of the extruded PET sheets drop below acceptable thresholds, the mechanical properties of the sheet will be compromised to an unacceptable level, resulting in downstream quality issues in thermoforming processes. This is often experienced when processing RPET, as the metallic catalysts used in the initial polymerization loses strength and cannot be revived, leading to a loss of IV and downstream processing issues.
How Can Companies Enhance the Recyclability of PET Packaging?
In many cases, “simplification” will help, such as eliminating colors, laminations and differentiated PETs. Doing so will help stream-line PET collection and recycling in general.
In addition, packaging engineers and designers should pay close attention to industry-accepted guidelines for recyclability, namely the APR Design Guide, How2Recycle, and the US Plastics Pact Problematic & Unnecessary materials list and either remove or find alternatives for materials, additives or components found to be detrimental to recycling.
What are the Opportunities for Using Recycled PET?
The closed-loop recycling using recycled PET bottles into new food-grade PET containers presents a significant opportunity to extend the environmental benefits and sustainability of PET as a packaging materials. There are two types of recycled PET converters can utilize – Post-Industrial Recycled (PIR) or Post-Consumer Recycled.
A bi-product of the PET pre-form process, PIR (also referred to as pre-consumer scrap) is process-scrap material that gets ground up and used back into the extrusion process at various percentages. Additionally, web scrap generated from the thermoforming process can be captured, processed and then incorporated back into the roll stock with virgin PET.
PCR is generally defined as finished goods that are sourced through established recycling streams such as curbside or consumer recycling streams. While there are several challenges ranging from collection/sorting costs to material and food contamination, the infrastructure established over the past decade has made it possible to produce Post-Consumer Recycled (PCR) PET solutions that meet the same quality and safety standards as virgin PET.
As regulations regarding the use of recycled content in packaging increase, the access to PCR materials will become more critical.
What are the Alternatives to Non-recyclable PET Packaging?
There are several alternatives which can be explored depending on application requirements. First, brand owners can look at simplification, and evaluate if components of the packaging material can be removed without negatively affecting packaging performance.
In addition, companies can look at replacing non-recyclable colored or barrier PET with polypropylene structures which can be recycled with RIC #5.
Taking that a step further, our new XPP solution can provide alternative solutions for both thermoformed and FFS applications providing full recyclability without compromise to performance and/or cost. This material offers enhanced stiffness compared to traditional polypropylene structures, offering a recyclable material solution without sacrifice to performance.
