Technological watch

Swedish appliance maker tests the bioplastics waters

Electrolux has built a prototype refrigerator using, where possible, bio-based plastics. ‘But we still have a lot to learn about these materials,’ said Marco Garilli, innovation expert at Electrolux during an interview at the 2018 NatureWorks Innovation takes Root Conference in San Diego. 

‘We know how conventional plastics work,’ explained Garilli. “We use PP, for washing machine tubs, for example, and POM in the aggressive environment of the dishwasher; PS in refrigerators, as well as PA, TPE and ABS.” In the interests of sustainability, he said, Electrolux was also exploring the use of recycled plastics and potential use of bio-based plastics for durable applications. 

For Electrolux, ‘acting sustainably’ is a fundamental strategic driver, along with creating better experiences for everyday life and continuous improvement. 

“Among the various parameters of sustainability, we have chosen to focus on the parameter of our CO2 footprint,” said Garilli. “We use LCA as the tool to quantify the impact of our appliances over their entire lifetime. In the circle: raw materials – process – produce components and our appliances – distribute our products – their use by the consumer, which strongly impacts on the life cycle – and then disposal, the choice of materials can have a very big effect.” 

With that in mind, the company decided to explore the impact of the use of biobased materials versus conventional plastics. 

Prototype development

The initial experimental steps were taken in 2011, but it was not until Electrolux came into contact with NatureWorks that a more structured approach was adopted. The Electrolux Global Connectivity & Technology Center (GC&T), where Marco Garilli is based, embarked on a collaboration with NatureWorks that continues to the present. “They helped us to really get to know their Ingeo PLA material and learn how to use it. We then wanted to take the next step to see what the material could offer to our appliances,” said Garilli. “We also looked at PHA, but the company we contacted indicated they couldn’t help, so we opted for the more reliable partner.”

Over the past several years, GC&T has therefore explored and tested how bioplastics can be applied in Electrolux products and packaging. Together with the Electrolux Purchasing and R&D departments for food preservation, and working with Frank Diodato, NatureWorks Business Director, who had been closely involved and who worked with Electrolux on evaluating the grades of Ingeo suitable for Electrolux’ applications, the decision was made to develop a prototype refrigerator in which all visible parts were made of biobased plastic. The technology brief demanded that the same production technologies had to be able to be used. The end product had to meet all the requirements and specifications of a conventional refrigerator, as well as being able to be recycled at the end of life, in order to fit within the concept of the circular economy. 

“We looked at all the different plastics used in the refrigerator, to see whether they could be replaced. It became obvious that wherever ABS had been used, this could be replaced by Ingeo PLA. In fact, all the styrenes could be replaced by PLA. We evaluated all the components one by one and found that the shelves, for example, could easily be made of PLA. Instead of using HIPS for the inner liner, we used 20% PMMA and 80% PLA. PMMA and PLA are completely miscible, which meant that the liner could be recycled. The ABS thermostat covers were replaced by covers made from a/cPLA. The door shelves, flaps and drawers, all formerly GPPS, could be replaced by a/PLA.

“NatureWorks worked closely with us on the development of specific grades for the project,” said Garilli, adding that there were a number of challenges that needed to be addressed, such as the low softening temperature of a/PLA and the fact that it is slightly less transparent than the styrenic materials. Mould shrinkage was another problem that needed to be solved, while another issue was cost. “PLA is more expensive than styrenics. HIPS and ABS are commodities. But we are confident that the price will come down.” 

Surprises

When asked about the advantages to using a bioplastic over a ‘conventional’ plastic, obviously the first thing Garilli pointed to was the environmental benefit calculated by using Ingeo PLA. “Looking at the plastics used, this prototype refrigerator had a carbon footprint that was 83% smaller than when using petroleum-based plastics. Per fridge, this was 22% smaller.”

However, there were also benefits relating to the properties, chemical and mechanical, of the bioplastic itself. “When it came to producing the refrigerator liners, which are big thermoformed products, the issue of distortion arises. There were basically two choices: we could produce the liners by thermoforming extruded amorphous PLA sheet or we could opt for a PMMA/PLA multilayer liner. As the latter was a known solution, it made sense to use it, and to go for a 100% PLA solution later, if it worked.”

The first surprise was how well it worked. “PLA has a much higher melt strength than HIPS,” explained Frank Diodato. “During thermoforming, the material is stretched, which results in tension. When using HIPS, a sheet with a thickness of minimally 3.5mm is required to avoid distortion issues, as HIPS does not stretch homogenously, but has different thicknesses in the middle part than in the corners. We were excited to find that with PLA, this was far more uniform, making it possible to reduce the layer thickness to 1.2mm, which not only meant that less material was used, but also that the weight of the liner was reduced.”

It was well known that the modulus of PLA was twice that of HIPS, Garilli noted. “What we didn’t know was whether this was a good or a bad thing. It turned out to be good – and provided important feedback from the project.”

An additional advantage is the fact that PLA, next to being tough, is also inherently resistant to food oils, he said, and the fact that it has a ‘superb’ appearance. “The material is a stable white, with an incredible gloss, much better than what can be achieved with HIPS.”

 What’s next?

Having demonstrated that it is possible to replace traditional plastics by Ingeo PLA in a durable application, Electrolux has put the project on hold until the time is right for a product launch. According to Garilli, the market will develop, but “when and how this develops depends on various factors, including the interest from the market”. 

“What we have built today is a prototype. We are waiting for the right moment to launch a product. But we are still continuously evaluating the possibilities to use bioplastics.”

This project has been co-funded with the support of the LIFE financial instrument of the European Union [LIFE17 ENV/ES/000438] Life programme

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Last update: 2019-05-09