Interview with Dr. Horacio J. Salavagione

Today we have the great opportunity to talk with Dr. Horacio J. Salavagione, Tenured Scientist since 2016, at the Spanish National Research Council (CSIC).

Could you explain de characteristics of the new adhesives with dual functionality and the process of delamination of multilayer packaging?

These new adhesives are materials that combine two specific functions in a unique polymer layer: easy separation after use and enhanced barrier properties. To achieve these functionalities, the adhesive incorporates appropriate chemical groups and nanoparticles. The former consists of chemical bonds that are reversible and sensitive to external stimulus, in this case, temperature, whereby these bonds can break/form by switching the temperature. The nanoparticles have a dual purpose, acting as radiation absorbers that generate local heat enabling the rupture of the so-called thermoreversible bonds and, in addition, they provide a barrier to gas diffusion due to a layered, 2-dimensional structure.

The aim of these new adhesives is to facilitate the delamination process of multilayer packaging by applying a simple thermal treatment. Before and during use, these new adhesives will behave similarly to standard adhesives used in laminates, maintaining their strong adhesive capacity. However, after use the application of a simple short-time thermal treatment triggers the opening of the thermoreversible bonds, which causes a notable loss of adhesion allowing easier separation of the different polymer layers. This will enable the recovery of cleaner materials for recycling or biodegradation.

How will Mandala solution change the paradigm of the current food and pharma packaging?

Nowadays 95% of the value of plastic packaging materials is lost after a short, single-use cycle. In the case of food and pharma packaging, it has become essential to cover, enhance and protect products at all stages of production; from processing and manufacturing, through handling and storage, to presentation and usage that meet the final consumer’s expectations. To achieve this, technological developments have led to the use of multi-layered multi-material packaging, which is composed of several different polymer layers, each with a specific function.

However, increasing packaging complexity to gain performance benefits also makes the packaging much more difficult to recycle, and because of this its end-of-life options are usually limited to either landfill or incineration.

The MANDALA project presents a sustainable solution for the plastic packaging sector directed to find, in the mid-term, a final solution based on multilayer monomaterial film packaging with functionalities compared to multimaterial film and fully produced with biobased & recycled polymers to reach a full circularity of resources. The MANDALA project will develop new products and technologies with the main objective of delaminating multilayer packaging with a clean separation of films and adhesives that will contribute to a valorisation of the recovered materials and a better end-of life scenario. The project includes partners from the entire value chain of this type of packaging, from design to recovery, and contemplates up-scaling the delamination and washing concept into a pilot semi-industrial line.  The functionality of the new adhesives will be validated with different product prototypes for the food and pharma sectors.

Could you please update our readers with the work and progresses done during these 20 months of the project lifespan?

This first part of the project has been really fruitful, and all the objectives planned have been achieved. The work done so far is mainly related with the development of new adhesives and can be divided into three main groups as: the synthesis of thermoreversible molecules, their incorporation into commercial adhesives and the incorporation of radiation absorbing nanoparticles.

Firstly, two thermoreversible molecules were designed and successfully synthesised from commercially available reagents. All experimental parameters were optimized and the thermoreversibility of these new molecules was demonstrated.

Secondly, these thermoreversible molecules were successfully incorporated into commercial PUR-based adhesives. The influence of the chemical structure of the thermoreversible molecules, the ratio between the different adhesive components, and curing variables were all analysed in order to tailor the switching temperature (the temperature at which the thermoreversible bonds will open) and optimise it for use within the adhesives.

Finally, to promote efficient thermal treatment at the interface in laminated multilayer films, radiation absorbing nanoparticles were incorporated to the new adhesive formulations to induce local heating by application of electromagnetic radiation. The influence of nanoparticle concentration and characteristics of the radiation were evaluated and was proved that the use of such nanoparticles drastically diminishes the time required for opening the thermoreversible bonds and the process can be remotely triggered, facilitating layer separation.

How will MANDALA project cooperate with the Sustainable Development Goals? Do you think that the project will have a real impact in society in a close future?

MANDALA will directly contribute to the SDGs, as the solution proposed in this project is expected to facilitate the separation of multilayer films currently used in food and pharma and recover the individual components of the multimaterial films after use and return them to the beginning of the cycle in a circular manner. The reutilization of the initial components will be a major step, and by optimizing the process to multiple reuses will save tons of polymers leading to the possibility of a real circular economy in multilayer packaging.

Today, MANDALA has covered less than half of its journey and the achievements so far are very promising as the new adhesives behave as expected and the first experiments on multilayer materials have shown good results. The next step focuses on the scaling-up of the lamination and delamination of multilayer materials and the overall impact will depend on the success of this process. If the project continues to advance as it has done so far, we hope that in less than two years we will be able to present a recycling solution for materials employed in food and pharma packaging. Therefore, we are convinced that the products and technologies developed in this project will have a marked impact on society in the not-too-distant future. Just to mention some relevant features, MANDALA aims to reduce the Environmental Footprint associated with the end-of-life phase of developed packaging products by at least 30% compared with existing products for similar applications.  Also, the project aims to achieve a 30% decrease in end-of-life costs by implementation of a delamination step in the recycling process, being highly competitive in the market.