The Reinholds project brings together the Politecnico di Milano, the Politecnico di Torino and Greenchemicals in a second joint research initiative focused on plastics recycling. Within the framework of the Alta Scuola Politecnica (ASP) programme, the team is working on the recycling of the polyethylene–aluminium (PE-Al, also termed polyAl) component of Tetra Pak packaging. The central technical objective is to investigate whether the low density polyethylene (LDPE) and aluminium residue can be converted, via extrusion, into aluminium hydroxide suitable for use as a non-halogenated flame retardant, for example in cable applications. The project builds on experience gained in the earlier Oracle project on XPS recycling for food-sector applications, which received the Alta Scuola 2024 prize for best project, and illustrates the growing role of multidisciplinary academic–industrial collaborations in addressing complex recycling challenges in multilayer packaging.
Reinholds: from multilayer packaging to flame retardant
Reinholds, whose full name is "REcycle INnovative of Tetrapak for HalOgen-free fLame-retarDant", focuses on one of the most widely used packaging solutions in the food and beverage sector. Tetra Pak packaging is a multilayer structure comprising paper, LDPE and aluminium. This configuration combines long shelf life, low weight for transportation and barrier protection for perishable contents, but it also complicates end-of-life management due to the intimate combination of different materials.
The established recycling scheme for such packaging generally proceeds in two stages. First, the cellulose fibres are separated and recovered, then reused for the production of new paper products. What remains is the so-called polyAl fraction, a mixture of LDPE and aluminium. This residue is more difficult to reuse, because the presence of aluminium alters the properties of the polymer phase and limits straightforward reprocessing routes based on conventional plastic recycling operations.
Reinholds directly targets this polyAl fraction. The project aims to study the feasibility of using an extruder to promote the conversion of the LDPE plus aluminium residue into aluminium hydroxide. If successful, the aluminium hydroxide obtained could be introduced as a non-halogenated flame retardant in downstream industrial applications. One of the main reference sectors in this context is the cable industry, where the use of halogen-free flame retardant systems is well established and closely linked to evolving regulatory and market requirements.
A key feature of the initiative is that it is embedded in the ASP framework, a two-year excellence programme that runs in parallel with the master’s degree and is reserved for selected students from the Politecnico di Milano and the Politecnico di Torino. Within ASP, multidisciplinary innovation and development projects are carried out in partnership with companies, research centres and public administrations, under the scientific supervision of academic staff from both universities.
Academic and industrial partners in the project
The academic component of Reinholds is provided by a team of six ASP students: Riccardo Sandon, Matteo Capolli, Eleonora Esposito, Sophie Vigè, Sophie Gorrex and Marco Urro. The work is coordinated by Professor Lidia Castoldi from the Department of Energy at the Politecnico di Milano and Professor Fabio Alessandro De Orsola from the Department of Applied Sciences and Technologies at the Polytechnic University of Turin. Laboratory activities are conducted at Polichem in Garlasco (Pavia), where the Greenchemicals laboratory and production plant are located.
On the industrial side, three members of Greenchemicals support the students in experimental work and project development: CEO Micaela Lorenzi, R&D and Technical Manager Barbara Chinello and Regulatory and R&D Technician Valentina Pelliccioli. Greenchemicals is an Italian company specialised in additives for the plastics industry, with particular expertise in sustainable solutions and halogen-free flame retardant formulations.
Additional industry partners include Prysmian, a major producer of cable systems for telecommunications and energy, and the Crosspolimeri Group. The latter operates in the field of cable compounds and comprises Crosspolimeri SpA as the parent company, Crosspolimeri AG Schweiz, Eurocompound Srl and ReCross Srl. Their involvement is relevant both for the definition of technical specifications for potential applications of aluminium hydroxide in cable compounds and for the evaluation of industrial feasibility and market perspectives.
The Alta Scuola project students with Polichem laboratory staff and Micaela Lorenzi (center)
Multidisciplinary scope and tasks
In line with ASP requirements, Reinholds is structured as a comprehensive multidisciplinary project, not limited to laboratory-scale validation of chemical transformations. The students are tasked with verifying the technical feasibility of the extrusion route for generating aluminium hydroxide from the PE-Al residue, including definition of process conditions and assessment of the impact on product quality and consistency. Experimental work aims to confirm whether extrusion can provide a controlled and scalable pathway to the desired inorganic phase while handling a heterogeneous feedstock.
In parallel with the technical validation, the team is carrying out an analysis of the overall process costs. This includes factors such as collection and transportation of the polyAl fraction, preprocessing requirements, energy consumption associated with extrusion and post-processing, and potential economies of scale. Economic assessment is crucial for understanding whether the proposed pathway can compete with existing recycling solutions and with conventional sources of aluminium hydroxide used in flame retardant formulations.
The project also requires identification and evaluation of specific application areas for the produced aluminium hydroxide. This involves studying the halogen-free flame retardant market, with particular attention to the cable sector, and mapping potential customers, performance requirements and regulatory drivers. On this basis, the team is working to outline a business model describing possible value chains that link beverage carton recycling streams to flame retardant compound production and, ultimately, to finished cable products.
The students conducting analyses at Polichem
Stakeholder engagement and market perspective
Beyond laboratory research and economic assessment, stakeholder engagement forms a further pillar of Reinholds. The students are expected to interact with recyclers in order to gauge their interest in supplying or processing the PE-Al fraction under the proposed scheme and to identify practical constraints linked to the variability and availability of polyAl residues. Through these interactions, the team aims to evaluate the feasibility of integrating the new process into existing collection and recycling infrastructures.
At the same time, the project calls for the involvement of potential downstream stakeholders, including compounders and cable manufacturers, who could integrate the resulting aluminium hydroxide into their halogen-free flame retardant systems. Dialogue with such stakeholders is intended to clarify performance targets, processing conditions and certification requirements, all of which are essential for designing a product that aligns with industrial practice.
A central deliverable of this work is a business model that can be presented to potential investors. This model is expected to combine technical, economic and market findings and to outline possible scenarios for implementation, including scale-up stages and partnership structures. The overall ambition is to demonstrate whether and how the recycling of the PE-Al component of Tetra Pak packaging can generate added value in a specialised market segment.
From Oracle to Reinholds: continuity in recycling-focused research
Reinholds follows the Oracle project, another ASP collaboration with Greenchemicals that focused on recycling of extruded polystyrene (XPS) in the food industry. Oracle, completed earlier, has already shown concrete impact in the field of plastics recycling and was recognised with the Alta Scuola 2024 prize for best project. According to the partners, this recognition underlines both the technical quality of the work carried out and the relevance of the topics addressed for the plastics value chain.
The ongoing Reinholds research is still at the development stage, but the preliminary results achieved so far are viewed positively by those involved. The experience and methodologies gained in Oracle, particularly in linking experimental research to market and regulatory analyses, provide a foundation for the current work and support Greenchemicals in its strategy of developing solutions consistent with its sustainability priorities, including halogen-free flame retardant technologies.
Next steps and timeline
Work on Reinholds officially started in May 2025 during the Green Plast trade fair in Rho, where the project kick-off meeting was held with Greenchemicals, the ASP students and potential stakeholders. Over the coming months, activities will continue with further laboratory tests, refinement of process parameters, in-depth market analysis and consolidation of contacts with industrial partners and recyclers.
The final discussion of the project by the student team is scheduled for September 2026. Until then, the consortium will continue to refine its assessment of the technical feasibility, economic viability and market potential of converting the PE-Al fraction of Tetra Pak packaging into aluminium hydroxide for use in halogen-free flame retardant systems. Updates on the Reinholds project and on related Greenchemicals initiatives are made available in the news section of the greenchemicals.eu website.
