Carl‐Christoph Höhne

The ageing behaviour of inverse vulcanised polymers, synthesised from fossil and renewable comonomers is investigated under thermal and radiative stress, aqueous environments and biological attack. Graphical abstract partly generated with NotebookLM.

The development of new materials that are inherently safe and sustainable has become a critical objective in the context of the green transition. This challenge is especially significant for plastics, which often contain complex mixtures of chemicals that may be released during various stages of their life cycle and that can pose risks to human health and the environment. Within this context, the Safe and Sustainable by Design (SSbD) framework was followed to support the design of an innovative epoxy–vitrimer composite that integrates non-releasable fire-retardant functionalities, aiming to produce safer, sustainable, and recyclable materials suitable for railway applications. A simple methodology was developed to identify release hotspots potentially affecting workers, consumers, and environmental species and organisms. Based on this, experimental simulations were conducted to evaluate the release of materials such as flame retardants, non-intentionally added substances, and microplastics at hotspots and to compare release profiles between a benchmark material and an SSbD alternative. The results demonstrate that the newly developed recyclable and less hazardous composites can also reduce material release under weathering and abrasion conditions.

Post-consumer blended textiles are utilised through selective PET glycolysis and upcycling of the cellulose-rich residue into reprocessable sulfur composites with enhanced mechanical properties. Image partly generated using Microsoft Copilot (Enterprise).

The development of new chemicals and materials that are inherently safe and sustainable throughout their entire life cycle has become a critical objective in the context of the green transition. This challenge is especially significant for plastics, which often contain complex mixtures of chemicals that may be released during various stages of their life cycle, from manufacturing to use and end-of-life management. Such releases can pose risks to human health and the environment. Within this context, the Safe and Sustainable by Design (SSbD) framework was followed to support the design of an innovative epoxy-vitrimer composite that integrates non-releasable fire-retardant functionalities, aiming to produce a safer, recyclable materials suitable for railway applications. This study presents the identification and quantification of potential releases as part of Steps 2 and 3 of the SSbD framework. A dedicated methodology was established to evaluate the potential release of materials such as flame retardants, non-intentionally added substances, and microplastics throughout the product’s life cycle. A systematic template was developed to identify release hotspots potentially affecting workers, consumers, and environmental species and organisms. Based on these findings, experimental simulations were conducted to compare release profiles between a benchmark and the SSbD alternative.

Asymmetrically substituted s‐triazine phosphonates with up to three different phosphonate groups C₃N₃RR'R” with R, R’, R”=PO(OR”’) and R”’=for example, methyl, ethyl, isopropyl or n‐butyl are interesting as polymer additives like flame retardants. Typically, these compounds are obtained by multiple synthesis steps. However, this leads to high production costs, which are a disadvantage for commercial use. Here we report the one‐step synthesis of mixtures of asymmetrical s‐triazine phosphonates which is an easy way to adjust the thermal behaviour and other properties such as viscosities of the compounds. The synthesis is based on a Michaelis–Arbuzov reaction. A complete conversion of the reactants to the target compounds is observed which was proofed by detailed ¹H, ¹³C and ³¹P NMR investigations and elemental analysis. The thermal behaviour was compared with thermogravimetric analysis (TGA).

The fire behaviour of electric vehicles (EVs) differs from that of vehicles with combustion engines. Especially the rechargeable energy storage system (REESS) requires special fire protection measures. The fire behaviour of materials for REESS housings plays an important role in the fire resistance of such systems. Full-scale fire resistance tests like gasoline pool fire tests on complete REESS according to the UNECE-R100-8E standard are mandatory for EVs. However, these tests are not applicable for materials used for REESS housings in the material and process development state, due to the high material demand and production costs of the REESS. Standard tests like the limiting oxygen index test, UL94-V test or cone calorimeter test are insufficient to analyse the fire behaviour of thermoplastic and thermoset materials in a gasoline pool fire. This paper describes a bench-scale fuel fire test including several test criteria to evaluate materials for REESS housings on a laboratory scale. This bench-scale fire test is demonstrated on two case studies: fibre-reinforced thermoset plates and thermoplastic sandwich structures.

The polymer electrolyte membrane (PEM) water electrolysis is a promising technology for the production of hydrogen from water using fluctuating renewable electricity sources. However, the investment cost of the PEM electrolysis technology has to be lowered considerably to achieve a widespread application. Polymer materials can be used as low‐cost materials to solve this issue. However, the conditions within the electrolysis cells are challenging for polymeric materials, especially for materials used within the oxygen‐evolving electrode. This study reports the new concept of electronically and protonic conductive polymer structures for the PEM water electrolysis produced by additive manufacturing and first results of investigations on compounds suitable for this concept.

Additive manufacturing offers a great potential for the production of objects with a tailor‐made inner structure especially in combination with material development in the field of polymer compounds. However, the design possibilities for the inner structure depend on printing resolution, accuracy, and reproducibility. The quality of small filigree objects printed by additive manufacturing processes for polymer materials like fused filament fabrication (FFF) depends on the polymer material itself as well as on the processing parameters in the additive manufacturing technology used. Here, the production of small porous structures by FFF with an Ultimaker 3 is analyzed using polylactic acid (PLA) as well as polymer compounds of PLA containing carbon nanotubes (CNTs) and polyvinyl alcohol (PVA) containing titanium dioxide (TiO₂). The influences of the calibration of the building plate, the heights of the 1^st, 2^nd, and 3^rd layers, and of particulate additives on the printing behavior of the polymer compound, and hence the resulting accuracy of the width of single printed lines, are studied. Additionally, the printing of lattice‐like scaffold structures using PLA/CNT forming the structure and PVA/TiO₂ as soluble support structure is described.

The growing importance of electric mobility has led to an increased demand for safety technologies in the automotive sector, such as the flame retardancy of materials used for electric vehicles. The fire protection of a fully equipped rechargeable energy storage system (REESS), including battery, housing, control electronics, etc., against a fuel fire must be tested according to UNECE Regulation No. 100 Annex 8E ‐ Fire Resistance (UNECE‐R100‐8E). To pass this fire retardancy requirement, the flame retardancy of the housing materials is of great importance. In this study, the flame retardancy of glass‐fiber‐reinforced polypropylene (PP‐GF) tape laminates containing the flame retardant magnesium hydroxide and different GF amounts, as well as sandwich structures of these PP‐GF tape laminates with a polypropylene bead foam (EPP) core, are investigated by a limiting oxygen index test, a UL94 test and a cone calorimeter test. Furthermore, a newly developed approach of a bench‐scale fuel fire test which simulates the fire treatment of the UNECE‐R100‐8E on component level is used.