The effect of six halogen-free flame retardant (FR) formulations was investigated on the thermal stability of two low-density polyethylenes (LDPE) and one linear low-density polyethylene (LLDPE), by means of thermogravimetric analysis (TGA) under nitrogen and air atmosphere. The relative data were combined with flammability properties and the overall performance of the FRs was correlated with the type of branching in the polyethylene grades and to their processing behavior. The thermal degradation kinetics was further determined based on the Kissinger and Coats-Redfern methods. In terms of flammability, the addition of a triazine derivative and ammonium polyphosphate at a loading of 35 wt. %. was found to be the most efficient, leading to UL 94 V0 ranking in the case of the LDPE grade produced in an autoclave reactor.

Electrical stimulation enhances functionality and accelerates maturation in biofabricated tissues, which are particularly important for muscle tissue engineering applications. Accordingly, there is demand for 3D-printable electrically conductive cytocompatible scaffolds that enable patient-specific geometries and localized electrical stimulation, as well as incorporate further maturation-promoting geometrical cues. Filament-based scaffolds from fused filament fabrication could overcome current limitations in geometric freedom, size and partially cytotoxic additives. In this study, biodegradable polylactic acid (PLA)-based conductive filaments incorporating graphene nanoplatelets (GNPs) or carbon nanofibers (CNFs) were developed via melt-mixing extrusion to possibly enable the electrical functionalization of muscle scaffolds. A two-stage process combining twin-screw and single-screw extrusion was preferred to allow for higher filler incorporation. Filament morphology, printability, electrical conductivity, and cytocompatibility were systematically evaluated. Homogeneous filaments containing up to 16 wt.% GNPs or 3.6 wt.% CNFs were successfully produced and processed by fused filament fabrication into scaffold geometries supporting myoblast orientation. Electrical conductivity was measured above 16 wt.% GNPs, with up to 2.7 µS/m, with printed constructs capable of connecting a circuit. GNP-based filaments were cytocompatible, supporting myoblast attachment and elongated morphology. An adjustable electrical stimulation setup demonstrated improved muscle maturation and contractile responses of C2C12 myoblasts, highlighting biodegradable conductive filaments’ potential for electrically active muscle tissue scaffolds.

This study provides insight into the causes of inferior long-term stability of nanocomposites based on organic layered silicates (OLSs) used for cable mantles. A hierarchy was established by analyzing bentonite products and their respective polyolefin nanocomposites. Thermogravimetric analysis (TGA), X-ray diffraction (XRD), gas adsorption, energy-dispersive spectroscopy (SEM-EDX), and infrared spectroscopy (IR) provided evidence for the adsorption of stabilizers onto the filler surface and thus their reduction in activity, promoting polymer oxidation. This behavior corresponds to the specific surface area of the incorporated OLS. Therefore, it can be stated that gas adsorption and XRD are especially useful for the evaluation of long-term photostability. It was revealed that photocatalytically active iron is of secondary importance since iron-rich bentonites still formed the most stable nanocomposite. This also applies to the Hofmann elimination products of the modifying agent, where higher contents do not accelerate the degradation process. No elimination products could be traced within the composites. Due to the polymer-filler interface being essential for long-term photostability, prior analysis of the filler surface properties can be used to estimate the stability of the respective nanocomposite as a rationale for product selection in the early stages of development. The reasons identified in this work for decreasing the long-term photostability of OLS nanocomposites compared with unfilled formulations is an important step toward increasing their stability.

With the Green Deal and the Circular Economy Action Plan, the European Union aims to replace half of the fossil-based raw materials in plastics with sustainable alternatives by 2030. In the plastic pipe industry, the use of post-consumer recyclates (PCRs) remains very limited due to reduced material quality, economic hurdles, limited availability, non-specific classification requirements, and a lack of testing standards. This paper presents two interconnected contributions to the quality-assured use of PCR for buried utility infrastructure made from Polyethylene (PE), Polypropylene (PP), and unplasticized Polyvinyl Chloride (PVC-U). First, a methodological framework, based on EN 13476, defines suitability as the intersection of material classification and application-specific requirements profile. A review of the current regulatory and technical situation reveals a systemic discrepancy: requirements profiles are oriented toward virgin material, while the scope of classification for PCR remains insufficiently defined. As a result, PCR is either used without adequate suitability assessment or blended with fillers, thereby limiting recyclability. Secondly, the review focuses on additive strategies, including restabilization, compatibilization, chain modification, and recyclate-compatible functional additives. These strategies are among the main technical solutions for closing the gap between PCR properties and the product’s requirements, reducing filler dependency, and enabling the long-term use of PCR in safety-critical applications.

With the Green Deal and the Circular Economy Action Plan, the European Union aims to replace half of the fossil-based raw materials in plastics with sustainable alternatives by 2030. In the plastic pipe industry, the use of post-consumer recyclates (PCR) remains very limited due to reduced material quality, economic hurdles, limited availability, non-specific classification requirements, and a lack of testing standards. This paper presents two interconnected contributions to the quality-assured use of PCR for buried utility infrastructure made from PE, PP, and PVC-U. First, a methodological framework, based on EN 13476, defines suitability as the intersection of material classification and application-specific requirements profile. A review of the current regulatory and technical situation reveals a systemic discrepancy: requirements profiles are oriented toward virgin material, while the scope of classification for PCR remains insufficiently defined. As a result, PCR is either used without adequate suitability assessment or blended with fillers, which limits the recyclability. Secondly, the review focuses on additive strategies, including restabilization, compatibilization, chain modification, and recyclate-compatible functional additives. These strategies are among the main technical solutions for closing the gap between PCR properties and the product's requirements, reducing filler dependency, and enabling the long-term use of PCR in safety-critical applications.