Potato Chip Bags Turned into Cooling Films

FRIDAY, AUGUST 11, 2023


Researchers from Bayreuth University have recently developed an upcycling process that transforms aluminum-plastic composite films into energy-saving films using polymer coatings.

The results of the study were recently published in the journals ACS Sustainable Chemistry & Engineering and Advanced Materials Technologies.

About the Research

According to the release, films made from APL are used to extend the shelf life of foods such as chips, roasted and powdered coffee, milk, fruit juices and other foods. During the COVID-19 pandemic, they were also used to package FFP2 masks and rapid tests. 

These films, the university explains, consist of several polymer layers and an aluminum layer, which protects the products from damaging factors, including sunlight, heat, moisture and oxygen. However, recycling such composite films is reportedly difficult due to the combination of different materials. 

To resolve this, researchers at Bayreuth studied the aluminium layer of APL packaging since it provides a mirror-like reflective surface. They found that if a clear polymer layer was applied, the radiation of thermal energy was increased and created a “powerful” cooling system.

A simple laminating film, like common ones found in office supply stores, is reportedly effective as a material for the coating, which creates cooling foils that can be applied to any surface in the open air prevent heating from sunlight.

Additionally, the ambient heat is diverted to the cool space without the need for an external energy supply, the team says. These effects are referred to as “passive daytime cooling,” which can lead to temperatures below the ambient temperature.

“Passive daytime cooling is made possible by the fact that the materials used meet special optical requirements. They must scatter or reflect as much of the sunlight as possible, which has a wavelength between 0.3 and 2.5 micrometers,” writes the university.

“On the other hand, in the wavelength range between 8 and 13 micrometers, the so-called sky window, they must emit as much thermal energy as possible into space in the form of infrared radiation. Aluminium-plastic composite foils fulfil these requirements very well.”

According to the university, Dr. Markus Retsch and his colleague Dr. Qimeng Song have tested different ways of turning potato chip bags and other APL packaging into efficient cooling materials.

Using the example of coated commercial potato chips bags, the Bayreuth researchers reportedly demonstrated that around 8% of the sunlight is reflected by the aluminum layer. The additional polymer coating of the new sustainable cooling foils improves the radiation in the wavelength range of the sky window and thus emits heat directly into space. 

According to the university, Dr. Markus Retsch and his colleague Dr. Qimeng Song have tested different ways of turning potato chip bags and other APL packaging into efficient cooling materials. Industrial processes that use polydimethylsiloxane (PDMS) as a coating material are also reportedly possible.

Potential uses for the upcycled APL packaging include heat shields on patios, balconies, exterior walls or roofs. Funding for the research was provided by a European Research Council “Proof of Concept Grant.” 

Potatoes in Coatings

Back in 2018, researchers from the Fraunhofer Institute for Manufacturing Engineering and Automation IPA, working in tandem with the Institution for Applied Polymer Research IAP, developed a cost-effective coating that uses potato starch.

According to the Fraunhofer Institute for Applied Polymer Research, paints and varnishes with bio-based binders or film formers have either been cost-prohibitive or could not meet the necessary requirements. This has changed with the use of modified starch.

At the time, testing was being conducted to determine the modified starch’s resistance to corrosion and adhesion to certain substrates.

More recently, in June of this year, researchers at the University of Manchester created a new material that they say could potentially replace concrete. The substance, referred to as “StarCrete,” was reportedly created by mixing “simulated Martian soil” with potato starch and a pinch of salt.

The article, published in Open Engineering, reported that potato starch can act as a binder when combined with a concrete-like material, such as simulated Martian soil.

StarCrete also reportedly tests at a strength of 72 Megapascals (MPa), making it twice as strong as regular concrete, which typically tests at around 32 MPa. Researchers added that StarCrete made from moon dust instead of Martian soil was even stronger, testing at over 91 MPa.

The team determined that a sack, or 25 kilograms (55 pounds) of potato chips, had enough starch to produce about half a ton of StarCrete, which is reportedly over 213 bricks of building material. Additionally, they found that a common salt known as magnesium chloride, obtainable from the Martian surface as well as astronaut tears, could significantly improve the strength of StarCrete.

Researchers stated that StarCrete could act as a greener alternative to traditional concrete, which reportedly accounts for 8% of global carbon dioxide emissions. As opposed to the high firing temperatures required for regular concrete production, StarCrete can reportedly be made in an oven or microwave at normal home baking temperatures.

   

Tagged categories: Asia Pacific; Coating chemistry; Coating Materials; Coating Materials - Commercial; Coatings Technology; Colleges and Universities; Cool Coatings; Cool walls; EMEA (Europe, Middle East and Africa); Green coatings; Latin America; North America; Polymers; Recycled building materials; Research and development; Sustainability; Z-Continents

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