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.

The commercially available partially bio‐based poly(butylene succinate) (PBS) and poly(butylene succinate‐co‐adipate) (PBSA) are subjected to prolonged and multiple extrusion cycles to investigate their thermal behavior. Empirically, both PBS and PBSA form branches at 190°C, with PBS possessing a higher tendency for branching than PBSA as studied by rheology and size exclusion chromatography (SEC). In each case, the branching is favored by fumaric acid moieties, making both PBS and PBSA susceptible to accelerated thermal oxidation. Indeed, the NMR signal attributed to fumaric acid disappears upon thermal processing of PBS and PBSA. Presumably, the bio‐based succinic acid used contains minor quantities of fumaric acid, yet still sufficient to cause this surprising processing behavior. The branching of both polymers is suppressed by stabilizers such as phenolic antioxidants, as proven by rheology and SEC. This is complemented by nuclear magnetic resonance (NMR), revealing that the fumaric acid signal is still well‐resolved in the stabilized processed samples.

This study provides insight into the accelerated hydrolysis of polyester PLA through the addition of phosphites based on pentaerythritol. To control hydrolysis and ensure processing stability, different types of phosphites and combinations of phosphites with acid scavengers were studied. Therefore, commercially available PLA was compounded with selected additives on a twin-screw extruder, and hydrolysis experiments were performed at 23 °C, 35 °C and 58 °C in deionized water. Hydrolysis of PLA was evaluated by the melt volume rate (MVR) and size-exclusion chromatography (SEC). For example, after 4 days of water storage at 58 °C, the number average molecular weight of the PLA comparison sample was reduced by 31.3%, whereas PLA compounded with 0.8% phosphite P1 had a 57.7% lower molecular weight. The results are in good agreement with the expected and tested stability against hydrolysis of the investigated phosphite structures. ³¹P-NMR spectroscopy was utilized to elucidate the hydrolysis of phosphites in the presence of lactic acid. With the addition of phosphites based on pentaerythritol, the hydrolysis rate can be enhanced, and faster biodegradation behavior of biodegradable polyesters is expected. Accelerated biodegradation is beneficial for reducing the residence time of polymers in composting facilities or during home composting and as litter or microplastic residues.

To use polylactic acid in demanding technical applications, sufficient long-term thermal stability is required. In this work, the thermal aging of polylactic acid (PLA) in the solid phase at 100 °C and 150 °C is investigated. PLA has only limited aging stability without the addition of stabilizers. Therefore, the degradation mechanism in thermal aging was subsequently investigated in more detail to identify a suitable stabilization strategy. Investigations using nuclear magnetic resonance spectroscopy showed that, contrary to expectations, even under thermal aging conditions, hydrolytic degradation rather than oxidative degradation is the primary degradation mechanism. This was further confirmed by the investigation of suitable stabilizers. While the addition of phenols, phosphites and thioethers as antioxidants leads only to a limited improvement in aging stability, the addition of an additive composition to provide hydrolytic stabilization results in extended durability. Efficient compositions consist of an aziridine-based hydrolysis inhibitor and a hydrotalcite co-stabilizer. At an aging temperature of 100 °C, the time until significant polymer chain degradation occurs is extended from approx. 500 h for unstabilized polylactic acid to over 2000 h for stabilized polylactic acid.

Polyvinyl butyral (PVB) is widely used as an interlayer material in laminated glass applications, mainly in the automotive industry, but also for construction and photovoltaic applications. Post-consumed laminated glass is a waste that is mainly landfilled; nevertheless, it can be revalorized upon efficient separation and removal of adhered glass. PVB interlayers in laminated glass are always plasticized with a significant fraction in the 20–40% w/w range of plasticizer, and they are protected from the environment by two sheets of glass. In this work, the aim is to develop a thorough characterization strategy for PVB films. Neat reference PVB grades intended for interlayer use are compared with properly processed (delaminated) post-consumed PVB grades from the automotive and construction sectors. Methods are developed to open opportunities for recycling and reuse of the latter. The plasticizer content and chemical nature are determined by applying well-known analytical techniques, namely, FT-IR, TGA, NMR. The issue of potential aging during the life cycle of the original laminated material is also addressed through NMR. Based on the findings, a sensor capable of directly sorting PVB post-consumer materials will be developed and calibrated at a later stage.

The development of suitable antioxidants has been a decisive element for the success of plastics in particular in the field of polyolefins. Build‐up from well‐accessible simple sterically hindered phenol structures, aromatic amines, and sulfur‐containing intermediates a comprehensive range of polymer and application‐specific products including multifunctional substances is commercially available today. Many successful products fulfill the market needs and are available on a global basis from different producers. Other promising products survives only for a short time. The future will see more stabilizers based on renewable resources and tailor‐made systems for mechanical recycling supporting the circularity of plastics. The present review covers historical developments with a focus on the last 30 years and intends to fill an information gap triggering potential novel aspects in the area of antioxidants.