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Reusable plastic: Considering environment, testing and end-of-life in design
By: Dan Andersson & Jan Hostettler
Reusability has a major impact on the plastic waste footprint, energy consumption and the reduction of emissions and waste. As a direct counter to the topic of single-use plastics, durable, reusable plastics are a sustainable and favored alternative by consumers to reduce waste.
As the second step of the waste hierarchy, reusability is an effective strategy to reduce waste, ensuring durability and longer-lasting quality of the plastics.
Designing reusable plastic products
EnvironmentWhen considering how the end-product will be used, other questions, like where will it be used, in what environment, and for what purpose must also be addressed. The answers to these questions determine the materials used to ensure the product will thrive in the intended reusable environment.
For example, if this is a product that is going to spend most of its time outside, enduring the elements, like sun, rain, and wind. If you design a reusable plastic product without these factors in mind, it will not last the time it needs to be a durable product.
Material selectionSelecting the optimal material and additives for an application is a critical early part of the design process. Reusable products designs must be built to last. This is achieved with a range of polymer additives, such as antioxidants, thermal stabilizers, UV absorbers, modifiers and resin selection that meets the life cycle demand, sterilization and reusability.
Consider a reusable plastic cup. Polymer selection and additive packages must withstand high temperatures and pressures through a dishwasher cycle while the structure must withstand the test of time by the user. When consumers pay more for durable products, they need to benefit from the longevity of the product.
The future of reusable plastic material selectionRenewable source reusable plastic products are the future of sustainability. Easy to replenish and designed to last, using them will benefit the industry, because we will:
1. No longer be solely reliant on petrochemical materials
2. Allocateresources to develop and optimize renewable sources; and
3. Reduce overall waste with increased life cycles for reusable products with a single end-user.
Development has a way to go to find renewable source materials that are durable enough to be reusable and sustainable. Some companies are developing products with renewable source materials, but do not have an appropriate end-of-life plan in place, disrupting the flow of recycling or may end up in places they should not be discarded in, resulting in greenwashing. If the products are not able to be appropriately disposed of, they cannot be considered sustainable and are merely contributing to another problem in the cycle.
Reusable plastic product testing
Mechanical testingMechanical testing assesses the durability of the reusable plastic, factoring its impact strength, flexural strength, scratch resistance and more to ensure the longevity of the product. This form of testing is rather quick to perform because the results are instant. With mechanical testing, multiple iterations are common to dial in additive concentrations as well. As an example, consider a bottle. The end-user must be able to use it every day and not break if it’s dropped or scratched throughout its life.
Chemical resistance testingWith chemical testing, chemicals like oils and acids are put the products to test their reaction and durability, reporting changes in aspects like weight, dimension, appearance and strength. Following the test, visual evidence such as cracking, clouding, decomposing, crazing and other signs will be used to help optimize the design to prevent such phenomena. As an example, consider reusable plastic cutlery. The end-user must be able to eat with this utensil and not have it degrade when it meets oils or grease in foods.
Outdoor and indoor resistance testingThe environment a product lives in plays a critical role in the design. This testing allows the assessment of how the materials withstand where the product ends up.
Outdoor testingAs an example, consider an outdoor product that every household has: trash bins. These are built with pigments, polymers and additives to create a structure that can thrive be reused year after year. Depending on the intended life span and use of the product, this testing phase can take as little as 500 hours, ranging up to more than 5,000 hours
With outdoor products, the kilo Langley(Kly) map is commonly used to calculate the addition rate of additives and the quality of pigments and polymers. This shows the solar radiation per year and mapped worldwide per region. For example, something that will thrive in Northern Europe is very different from the South of Europe; an outdoor product made to last 10 years may last less than half its lifetime in areas with higher Kly.
Indoor testingAs an example, consider a reusable plastic cup. This needs to have a high-temperature resistance is key to withstand a dishwasher without degrading or deforming the product.
The end-of-life challenge
The key end-of-life challenge with reusable plastics comes down to education and development. We see two obstacles:
- Consumers are still confused about how to dispose of some reusable plastics
- Collection services are still developing to better bring reusable items back into the recycling streams, but aren’t fully implemented today
These two aspects need to be aligned to move towards a circular economy.
Some companies are planning to develop their own in-house recycling methods for such products, while others will wait for governments and recycling organizations to build this out in the coming years.
The outcomes of reuse
Additionally, the rise in reusability allows less material to be consumed for the same purpose. With challenges in the supply chain being a frequent headline over the last two years, creating one durable product built to be repeatedly used by the consumer will lower the amount of materials needed to develop products and reduce the amount of landfill waste.
With the shift towards reusable products rising, and new markets and applications being explored every day, the potential for reusability is endless and will continue to grow and change in the coming years.
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