Study: Is rPET suitable for hot-fill containers?

PlasticsToday is pleased to debut a new blog series from the plastic packaging experts at Plastic Technologies, Inc. (Holland, OH).

With brand owners continuing to challenge themselves to bring their products to market in packaging that not only delivers the desired performance requirements, but also minimizes the carbon footprint, it’s logical that incorporating a percentage of recycled content should be considered.

Recycled polyethylene terephthalate, or rPET, is one of those materials that many have used to minimize dependence on virgin materials. While this exercise has played out a significant number of times in consumer product goods, water and carbonated beverage applications, it has happened much less frequently with hot-fill food and beverage containers.

To better understand the viability of rPET use in hot-fill containers, Plastic Technologies, Inc. conducted a research study. We found that the use of rPET in hot-fill packages has no significant adverse impact on the bottle performance until the blend exceeds 50%.

PTI rPET performance chart

Even at 100% rPET resin use, the performance of the package used in our study was still acceptable. Haze and yellowing were the main impacts of higher rPET levels. This is similar to what has been experienced with containers that are not hot filled. However, the typically-thicker walls of hot-fill bottles may result in slightly more noticeable haze or yellowing than other applications such as very thin-walled water bottles.

Study parameters

We evaluated virgin PET and two different rPET resins added to virgin PET at 25%, 50% and 100% levels. A 27g commercially available 500-mL six-panel hot-fill bottle and preform were used for the study. Bottles containing recycled-content variables were processed similarly to maintain equivalent bottle wall thicknesses and maximize preform temperatures. The objective was to ensure that the only difference was the amount of recycled content.

The bottles were then tested to determine hot-fill and top load performance, wall thickness, color, haze, crystallinity and acetaldehyde (AA) content. Following are the main study conclusions:

• All of samples passed the standard performance specifications for hot fill bottles, even at high percentages of rPET;

• Shrinkage increased slightly as the recycled content grew above 50%, but the bottles remained within the specification;

• The drawbacks of high rPET content are increased yellowing and higher haze levels. However, these are aesthetic issues and do not impact performance.

Therefore, we were able to conclude that converters and brand owners can use up to 50% good quality rPET to produce hot-fill bottles without performance being negatively impacted. rPET levels greater than 50% can also be used, however desired package aesthetics will be undermined and essentially drive the acceptable level.Tracy Momany, PTI

Tracy Momany is vice president, product development group, Plastic Technologies, Inc.  During her 20-year career, Momany has directed hundreds of package development projects including many custom container designs for food, beverage, hot fill and carbonated soft drink applications.

Plastic Technologies, Inc. (PTI) is recognized worldwide as a leading resource for preform and package design, package development, rapid prototyping, preproduction prototyping, and material evaluation engineering for the plastic packaging industry. For more information contact or email [email protected] or phone 419-867-5424.

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