Extrusion Experiments Research Articles

Texture evolution induced by extrusion parameters and its effect on strengthening-toughening mechanisms of Al-Mg-Si-Cu-Mn alloys

In this study, extrusion experiments were carried out on Al-Mg-Si-Cu-Mn alloys with different extrusion ratios (ERs), extrusion temperatures (ETs), and extrusion speeds (ESs). By using electron backscatter diffraction (EBSD) analysis, tensile testing, and other analytical means, the evolution of microstructure, texture, and properties of the extruded alloys was systematically investigated, and the strengthening-toughening mechanism induced by the extrusion parameters was revealed. It was found that the strength of the extruded alloy shows a tendency to first increase and then decrease with the increase of the ER and ES, and the ‘critical ER' and ‘critical ES' are 29.5 and 2.5 mm/s, respectively; the strength of the extruded alloy gradually increases with the increase of the ET. The alloy achieved excellent strength-toughness matching at the ER of 29.5, ET of 480 °C, and ES of 2.5 mm/s. The yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) of the extruded alloy at this condition were ∼169.58 MPa, ∼314.36 MPa, and ∼16.57 %, respectively. This excellent strength-toughness matching is mainly related to the following aspects: 1) grain refinement provides high grain boundary strengthening effect and appropriate work hardening ability; 2) <111>//ED texture has a strong preferential orientation; 3) the variation trend of dislocation density is importantly related to <111>//ED and EXa{011}<111> textures; 4) Cube{001}<100> and Goss{011}<100> textures have a softening effect. The above findings provide new insights into the potential mechanisms of hot extrusion forming of aluminum alloys, which are of important guiding for the design and development of aluminum alloys with excellent strength-toughness combinations.

Numerical simulation and experimental investigation of coating influence on extrusion tap wear

In order to improve the service life of extrusion taps and reduce their wear, this paper adopted the coating-simulation technology to investigate the influence laws of tool coating type and coating thickness on extrusion torque, extrusion temperature and wear amount. The validity of the numerical simulation results is confirmed through internal thread extrusion experiments. The results showed that the extrusion torque and extrusion temperature of single-layer coating and composite coating showed a tendency of decreasing and then increasing with the increase of the coating thickness; the extrusion torque and extrusion temperature of the double-layer coating increased with the increase of the coating thickness; the wear amount of the three types of coatings increased with the increase of the coating thickness. The TiAlN single coating demonstrates the most pronounced impact on decreasing extrusion torque and temperature (3.82 N·m and 88.4 °C), resulting in a smooth extrusion process. The TiAlN–TiAlN double coating exhibits the lowest wear amount of 0.076 mm. The utilization of numerical simulation proves to be a dependable approach for evaluating the efficacy of tool coatings, and reasonable selection of coating type and thickness can effectively reduce the extrusion torque, extrusion temperature and wear amount.

System-agnostic prediction of pharmaceutical excipient miscibility via computing-as-a-service and experimental validation

We applied computing-as-a-service to the unattended system-agnostic miscibility prediction of the pharmaceutical surfactants, Vitamin E TPGS and Tween 80, with Copovidone VA64 polymer at temperature relevant for the pharmaceutical hot melt extrusion process. The computations were performed in lieu of running exhaustive hot melt extrusion experiments to identify surfactant-polymer miscibility limits. The computing scheme involved a massively parallelized architecture for molecular dynamics and free energy perturbation from which binodal, spinodal, and mechanical mixture critical points were detected on molar Gibbs free energy profiles at 180 °C. We established tight agreement between the computed stability (miscibility) limits of 9.0 and 10.0 wt% vs. the experimental 7 and 9 wt% for the Vitamin E TPGS and Tween 80 systems, respectively, and identified different destabilizing mechanisms applicable to each system. This paradigm supports that computational stability prediction may serve as a physically meaningful, resource-efficient, and operationally sensible digital twin to experimental screening tests of pharmaceutical systems. This approach is also relevant to amorphous solid dispersion drug delivery systems, as it can identify critical stability points of active pharmaceutical ingredient/excipient mixtures.

In situ conductometry for studying the homogenization of Al-Mg-Si alloys and predicting extrudate grain structure through machine learning

In industrial practice, no sensors capable of obtaining microstructural information in situ during thermo-mechanical processing of Al alloys are commonly employed. Inductive electrical conductivity measurement is safe, inexpensive, and capable of acquiring valuable information about precipitation and dissolution processes. However, commercial eddy current sensors work only at low temperatures near room temperature and are thus not suitable for in situ conductometry during heat treatments of Al alloys. We designed a high-temperature eddy current sensor and performed in situ conductometry during the homogenization of six Al-Mg-Si wrought alloys, three of which are experimental recycling-friendly alloys with increased Fe content. The results are interpreted with regard to microstructural investigations, and the advantages and limitations of our approach are discussed. As a proof-of-concept, we show how the conductivity curves and extrusion process parameters can be combined to predict final extrudate grain structures using machine learning. To achieve this, we employed finite element simulation of extrusion coupled with microstructural simulation over a wide parameter range, validated by extrusion experiments and metallography, and trained a feedforward neural network. We believe our interdisciplinary approach can lead to improvements in the industrial processing of Al wrought alloys.

Numerical simulation of friction extrusion: process characteristics and material deformation due to friction

This study employs a finite element thermo-mechanical model, using a Lagrangian incremental setting to investigate friction extrusion (FE) under varying process conditions. The incorporation of rotation in FE generates substantial frictional heat, leading to significantly reduced process forces in comparison to conventional extrusion (CE). The model reveals the interplay between temperature, strain, and strain rate across different microstructural zones of the resulting wire. Specifically, the sticking friction condition in FE enhances initial shear deformation, aligning with a homogeneous spatial strain distribution and predicting complete grain refinement in the extruded wire, as per Zener-Hollomon calculations. On the other hand, under the sliding friction condition in FE, the shear deformation is reduced which results in an inhomogeneous microstructure in the extruded wire. The analysis of material flow in the workpiece reveals distinct transitions from the base material to the thermo-mechanically affected zones. The simulated process force, thermal history, and microstructure during sliding friction conditions align well with the findings from performed friction extrusion experiments.

Study on the Melt Rheological Characterization of Micro-Tube Gas-Assisted Extrusion Based on the Cross-Scale Viscoelastic Model.

In the micro-tube gas-assisted extrusion process, flow theories ignoring cross-scale viscoelastic variations fail to effectively characterize the rheological state of the melt. To investigate the impact of cross-scale viscoelastic variation on the quality of the micro-tube gas-assisted extrusion, a 3D multiphase flow extrusion model incorporating a double gas-assisted layer was developed. Subsequently, we modified the DCPP constitutive equations based on the cross-scale factor model. Both the traditional and gas-assisted extrusions were simulated under macroscale and cross-scale models using the Ansys Polyflow. Finally, using the established gas-assisted extrusion platform, extrusion experiments were conducted. The results indicate that, owing to the reduced melt viscosity under the cross-scale model, the deformation behavior of the melt is more pronounced than in the macroscale model. The cross-scale model's numerical results more closely match the experimental outcomes under the same parameters, thereby confirming the feasibility of the theoretical analysis and numerical simulation. Moreover, the predictive capability of the cross-scale model for the micro-tube gas-assisted extrusion is further validated through numerical and experimental analyses with varying parameters. It is demonstrated that the cross-scale viscoelastic variation is a critical factor that cannot be overlooked in the gas-assisted extrusion.

A novel flexible composite phase change material applied to the thermal safety of lithium-ion batteries

Large deformation of lithium-ion batteries (LIBs) under mechanical load can cause internal short circuit of the battery. Further, the LIBs generate a large amount of heat during the rapid charging and discharging process. The internal short circuit and heat accumulation in the battery can lead to explosion or fire, so mechanical damage and thermal runaway are the two major safety issues that hinder the practical application of LIBs. To this end, we have designed a new type of flexible composite phase change material (FCPCM) with dual functions of anti-extrusion and heat absorption. Firstly, paraffin wax (PW) is adsorbed in the pores of expanded graphite (EG) to obtain EG/PW composite phase change material (CPCM). Then, the powdered PW/EG and flake copper powder (FCP) as the heat conductive filler are coated in a thermoplastic elastomer (TPE) for secondary encapsulation, and the FCPCM with a high latent heat (137 J/g) is obtained. TPE not only reduces the leakage rate of PW but also improves the deformation capacity of CPCM and absorbs extrusion energy. As a filler with high thermal conductivity, FCP can effectively improve the thermal conductivity of the FCPCM. When the FCP content is 5 wt%, the thermal conductivity is as high as 3.357 W/mK. In the battery extrusion experiment, when the loading displacement reaches 13 mm, the battery does not suffer mechanical damage and internal short circuit. Next, the prepared FCPCM is applied to the thermal management of a battery. Experiments and simulations were combined to investigate the heat dissipation capacity of the FCPCM for battery at different discharge rates and different ambient temperatures, and 3 cycles at the maximum discharge rate (5C) and an ambient temperature of 30 °C were able to meet the requirements for practical use. The results verify that FCPCM exhibits immense application potential in the thermal management of batteries. Overall, we provide a new method for the design of CPCMs with excellent mechanical extrusion energy absorption and heat dissipation performance.

Radical scavenging and processing stability of novel biobased stabilizers in polypropylene

Bio-based molecules show great research potential to achieve alternatives to petrochemically produced products. Therefore, biogenic stabilizers (vanillates, syringates and gallates) were prepared, which were subsequently characterized by various analytical methods. Nuclear magnetic resonance spectroscopy was used for structural elucidation. Thermal stability and thus suitability for polymer processing were confirmed by thermogravimetric measurements. To assess the stabilizing effect, radical efficiency was determined using 2,2-diphenyl-1-picrylhydrazyl assays. Polymer compounds were processed in an extruder as well. In these prolonged extrusion experiments, the stabilizing effect in the melt was revealed.

Stabilization of polyethylene with grape pomace extract: Effect of natural oil content

The winery waste of a white grape was extracted in two different ways to produce extracts, one containing the natural oil of the waste and one without it; the goal of the work was to determine the positive or negative influence of the natural oil content of the extract on its stabilization effect and efficiency. The polyphenol content of the extracts was moderate, but their DPPH assay proved their antioxidant effect. The two extracts were added to polyethylene in concentrations between 0 and 2000 ppm, and their stabilizing efficiency was determined in multiple extrusion experiments. The extracts stabilized polyethylene adequately; their efficiency was only slightly smaller than that of the commercial hindered phenolic antioxidant, Irganox 1010. The solubility of the extracts in PE is much larger, 280 ppm, than that of a flavonoid-type natural antioxidant, quercetin (15 ppm). The presence of the oil had only a slight effect on stabilization efficiency, and its influence on properties is more beneficial than harmful. It decreases interactions among polyphenol molecules, improves the processability of the polymer, and increases homogeneity slightly. Accordingly, an extraction step can be saved during the preparation of the product, thus offering an economic advantage.

Charge weld evolution in hollow aluminum extrusion: Experiments and modeling

Charge welds occur in billet-to-billet extrusion processes due to the transition between successive billets. The material in this transition zone is typically characterized by substandard mechanical properties. In industrial practice, a specified length of the extruded profile is cut away and recycled as in-process scrap. Therefore, understanding the extrusion mechanisms affecting the properties of the charge weld is crucial to controlling product quality, reducing non-conformities and improving the extrusion yield. This paper provides new insights into thermo-mechanical mechanisms associated with charge weld of circular aluminum tubes. A large number of carefully-controlled, full-scale extrusion experiments were conducted in an industrial environment to research charge weld evolution mechanisms and influential parameters. In addition, a finite element (FE) model was developed to predict the charge weld evolution across the cross section and along the profile. The experimental and numerical results show good agreement in terms of the location of the charge weld within the extruded profile. Moreover, a comparison with analytical models in the literature reveals that the FE model provides a significantly more accurate prediction of the length of the extruded profile affected by the charge weld (‘scrap length’). Based on the validated FE model, a sensitivity study was done to explore the effect of process parameters on charge weld evolution, particularly focusing on material flow and dead metal zone. The results show that the ram speed influences the charge weld evolution, while changes in billet temperature are insignificant. In conclusion, the findings presented in this study provide new insights that serve as practical guidance to the mechanism of charge weld evolution. They also highlight the applicability and limitations of numerical and analytical methods in assessing industrial extrusion problems.

Microstructure and mechanical properties of longitudinal weld in 6005A aluminum alloy profile extruded by a porthole die

Porthole die extrusion experiments were carried out on 6005A aluminum alloy under the billet heating temperatures of 420–570 °C and ram speeds of 1–120 mm/min. The effects of extrusion parameters on the microstructure and mechanical properties in the longitudinal weld of profiles were investigated. It was found that the crystal orientation of longitudinal weld region showed the characteristics of gradient arrangement with different oriented grains wrapped in layers and symmetric along the welding line. The Copper{112}<111> grains are formed at the welding line under the combined effect of shear and compression, and the Goss{110}<100> grains are formed on their both sides due to dynamic recrystallization. A shear band is formed when part of metals flow through the 45° inclination angle of port bridge due to a sudden change in velocity, causing the Goss{110}<100> texture in local region to rotate to Brass{110}<112> texture. The 6005A aluminum alloy profiles mainly contain β (Mg2Si) phase, Q (Al3Mg9Si7Cu2) phase, AlCrMnSi phase and AlFeMnCrSi phase. Appropriately increasing billet heating temperature and ram speed can promote dynamic recrystallization and the dissolution of β-phase and Q-phase, thus improving the strength and hardness of the profile. However, when the billet heating temperature is too high, the strength and hardness are reduced instead due to grain coarsening. The profile extruded at billet heating temperature of 510 °C and ram speed of 120 mm/min has the best mechanical properties, with the tensile strength in 0° direction and hardness at the welding line of 179.93 MPa and 52.2 HV, respectively.

Evaluation of viscosities of typical drainage fluids to promote more evidence-based catheter size selection

Percutaneous drainage is a first-line therapy for abscesses and other fluid collections. However, experimental data on the viscosity of body fluids are scarce. This study analyses the apparent viscosity of serous, purulent and biliary fluids to provide reference data for the evaluation of drainage catheters. Serous, purulent and biliary fluid samples were collected during routine drainage procedures. In a first setup, the apparent kinematic viscosity of 50 fluid samples was measured using an Ubbelohde viscometer. In a second setup, the apparent dynamic viscosity of 20 fluid samples obtained during CT-guided percutaneous drainage was measured using an in-house designed capillary extrusion experiment. The median apparent kinematic viscosity was 0.96 mm2/s (IQR 0.90–1.15 mm2/s) for serous samples, 0.98 mm2/s (IQR 0.97–0.99 mm2/s) for purulent samples and 2.77 mm2/s (IQR 1.75–3.70 mm2/s) for biliary samples. The median apparent dynamic viscosity was 1.63 mPa*s (IQR 1.27–2.09 mPa*s) for serous samples, 2.45 mPa*s (IQR 1.69–3.22 mPa*s) for purulent samples and 3.50 mPa*s (IQR 2.81–3.90 mPa*s) for biliary samples (all differences p < 0.01). Relative to water, dynamic viscosities were increased by a factor of 1.36 for serous fluids, 2.26 for purulent fluids, and 4.03 for biliary fluids. Serous fluids have apparent viscosities similar to water, but biliary and purulent fluids are more viscous. These data can be used as a reference when selecting the drainage catheter size, with 8F catheters being appropriate for most percutaneous drainage cases.

Effects of rapeseed protein addition on soybean protein-based textured protein produced by low-moisture extrusion: Changes in physicochemical attributes, structural properties and barrel flow behaviors

This study investigated the potential of rapeseed protein as a novel alternative protein source in meat analogs produced by extrusion cooking technology. To study the substitutability of rapeseed protein to soybean protein, the addition ratios of rapeseed protein to soybean protein in the extrusion experiment were 0:50, 10:40, 20:30, 30:20, 40:10 and 50:0 (w/w), respectively. The results showed that adding 0–20% rapeseed protein not only decreased the specific mechanical energy and mass flow rate of the mixture during extrusion, but also enhanced the hardness and chewiness of the extrudates while reducing their elasticity and resilience. In addition, increasing the amount of rapeseed protein may lead to decreased expansion characteristics, internal pore structure, and water absorption rate of the extrudates, as well as a decrease in brightness and an increase in redness on the surface. Weibull model could well describe the rehydration behavior for dynamic fitting of the extrusion rehydration process. Moreover, with the increase of rapeseed protein substitution, the content of disulfide bonds, and the proportion of relatively ordered protein secondary structures with high stability increased, and the degree of protein denaturation decreased. Besides, the degree of starch gelatinization reduced and the thermal stability of extrudates improved. Interaction analysis indicated that disulfide bonds are the primary force maintaining protein-mediated interactions in the extrudates. The incorporation of rapeseed protein shortened the mean residence time of molten feedstock and shifted the flow state to plug flow. Overall, our investigation suggests that within low levels of addition (≤20%, w/w), rapeseed protein has the potential to partially substitute for the soybean protein-based textured proteins. High substitution levels or complete substitution are not feasible due to the relatively low expansion and rehydration rates.

Characterizing stable nanocrystalline Cu-Ta behavior and failure dynamics under extremes of strain rate, strain, temperature and pressure by modified dynamic tensile extrusion

This work presents characterization of thermo-mechanically stable, bulk nanocrystalline (NC) Cu-Ta alloys under a combination of extreme states using high-temperature, dynamic tensile extrusion experiments. The NC Cu-Ta was subjected to high dynamic strain rates up to 105/s, large plastic strains of 100–500 %, and high homologous temperatures greater than 50 %TM. This combination of thermo-mechanical conditions provides a unique look at how these extremely stable microstructures can accommodate and reconfigure under situations where dislocation activity is the most extreme, given constitutive relationships between strain rate, dislocation nucleation, and plastic work. Elevated temperature tests results reveal NC Cu-1Ta alloys are capable of forming a coherent jet, (25 mm in length by 1.8 mm in diameter) as it accelerates out of the die after being dynamically extruded. Microstructural analysis reveals that unlike previous reports on conventional un-stabilized nano or near nano-grained Cu, NC Cu-Ta alloys behave differently. They do not undergo grain coarsening via a nucleation and growth process, but rather behave identically to that of coarse-grained Cu. The NC grains elongate along the extrusion direction and at the same time shrink in diameter and develop a <111> type texture. Ultimately, the occurrence of premature dynamic failure was attributed to the inherent constraints posed by processing defects during synthesis.

Numerical and experimental studies on the influence of gas pressure on particle size during gas-assisted extrusion of tubes with embedded antibacterial particles

Abstract During the gas-assisted extrusion process of plastic tubes embedded with antibacterial particles, the particles tend to agglomerate. The dispersion effect of these agglomerates using the nozzle-pressure-difference method is significantly influenced by the gas flow state. Therefore, this study establishes the nozzle dispersion model. The gas flow state near the nozzle is simulated and analyzed by using Ansys Fluent software. Gas-assisted extrusion experiments are conducted with different nozzle inlet pressures, and the size distribution of antibacterial particles is observed by using electron microscopy. The simulation results indicate that increasing the nozzle inlet pressure enhances the dispersion effect and expands the effective dispersion area. The experimental results demonstrate that using the nozzle disperses the agglomerates into particles with a diameter of approximately 100 nm. Furthermore, the nanoparticles diameter size decreases with the increase of the inlet pressure, validating the accuracy of the numerical analysis results.

Surface and volume effects in multimodal ultrasonic vibration assisted micro-extrusion forming: Experiments and modelling

Ultrasonic vibration (UV) has been widely used in microplastic forming with its advantage of improving the metal plasticity. However, the coupling mechanism of the surface and volume effects of UV is still unclear. In this study, the multimodal ultrasonic vibration (tool vibration (TV) and mold vibration (MV)) assisted micro-forward extrusion (MFE) and micro-backward extrusion (MBE) experiments of copper T2 were conducted. An analytical method for ultrasonic surface effect in multimodal UV assisted micro-extrusion forming process was proposed, and a decoupling analysis method of ultrasonic surface effects and volume effects was also presented. The results indicated that the extrusion stress reduction caused by surface effect and volume effect were increased with the increase of ultrasonic amplitude, and the extrusion stress reduction of MV was greater than that of TV. The surface quality of the sample was improved by UV, and the surface roughness with MV was lower than that with TV. In addition, the coupling mechanism of ultrasonic surface effect and volume effect was revealed, and a comprehensive analytical model was developed considering both ultrasonic surface effect and volume effect. The predicted results of the extrusion stress were well agreed with the experimental results, with a maximum error was only 3.2%. These results provide a theoretical basis for further studying the mechanism of UV assisted micro-forming.

Temperature rises and constitutive equation of homogenized 6063 aluminum alloy for extrusion

The effect of temperature rises on the flow stress and constitutive equation of homogenized 6063 aluminum alloy was studied by theoretical analysis, numerical simulation, and experiments. The results showed that the temperature rises increased with the decreases of deformation temperatures and the increases of strain rates, which caused the flow softening. The modification of the flow stresses of 6063 aluminum alloy was carried out. A strain compensation constitutive equation based on the Arrhenius equation and Zener-Hollomon parameter was introduced to predict the flow behavior of 6063 aluminum alloy. The calculated flow stresses were consistent with the experimental results, and its average absolute relative error was only 3.25%. Finally, the established constitutive equation was substituted into the Deform-3D software. The corresponding extrusion experiments were carried out. The maximum extrusion pressures and maximum exit temperatures in the numerical simulation were in good agreement with those in the experiments, which confirmed the accuracy and reliability of the established constitutive equation.

Antioxidant Activity of Biogenic Cinnamic Acid Derivatives in Polypropylene.

Antioxidants (AOs) from natural resources are an attractive research area, as petroleum-based products can be replaced in polymer stabilization. Therefore, novel esters based on the p-hydroxycinnamic acids p-coumaric acid, ferulic acid and sinapic acid were synthesized and their structure properties relationships were investigated. The structures of the novel bio-based antioxidants were verified using NMR and Fourier-transform infrared (FTIR) spectrometry. The high thermal stability above 280 °C and, therefore, their suitability as potential plastic stabilizers were shown using thermal gravimetric analysis (TGA). The radical scavenging activity of the synthesized esters was evaluated by using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. Stabilization performance was evaluated in polypropylene (PP) using extended extrusion experiments, oxidation induction time (OIT) measurements and accelerated heat aging. In particular, the sinapic acid derivative provides a processing stability of PP being superior to the commercial state-of-the-art stabilizer octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

Fabrication of SiC/Al Functionally Graded Materials Via Filtration Extrusion

Functionally graded materials (FGMs) have broad application prospects owing to their outstanding material properties. Herein, a filtration extrusion device is designed, and low‐content SiC/Al composites are used to explore the feasibility of applying filtration extrusion techniques to the fabrication of FGMs. The results suggest that the extrusion force increases monotonically with an increase in the filtration extrusion ratio. Furthermore, the filtration extrusion process can be divided into two stages based on the change trend of extrusion pressure: at stage 1, extrusion force is small and increases slowly. At stage 2, the extrusion force increases significantly and rapidly. During the filtration extrusion process, the larger the initial content, the lower the extrusion temperature, the smaller the hole‐separation mold area ratio, the faster the increase in the extrusion force, and the greater the maximum extrusion force during the extrusion process. Based on filtration extrusion experiments for various extrusion distances, it is found that the transition from the nonflow to the flow influence zone is primarily responsible for the enrichment and gradient distribution of SiC particles. The SiC particles are distributed in a gradient, and the content of SiC particles near the separation mold is higher than that on the other side.

Comparative study on the degradation of HDPE, LLDPE and LDPE during multiple extrusions

Stricter regulations of plastics waste and the enforcement of higher recycling quotas has led to an increasing interest in recycling. One of the most prominent recycling strategies is mechanical recycling, which is based on sorting, pre-treatment and remelting of plastics waste. As repeated reprocessing, may be associated with a reduced quality of the obtained recyclates, approaches for the characterization of these materials by analytical techniques need to be developed. These should help to identify recyclates that will not fulfil the requirements but also to provide data allowing to take countermeasures (such as addition of a certain percentage of virgin material and/or polymer stabilizers). Three different polyethylene (PE) types (high-density (HDPE), linear low-density (LLDPE) and low-density (LDPE)) were subjected to long-time extrusion experiments in order to gain a better understanding of degradation occurring during multiple recycling steps (as expected in a circular economy). Unstabilized material as well as PE with two different stabilizers, Irganox 1010 (IX1010) and Irgafos 168 (IF168) were investigated, employing high temperature gel permeation chromatography with infrared spectroscopic detection (HT-GPC-IR), thermo desorption gas chromatography-mass spectrometry (TD-GC-MS) and high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (HPLC-qTOF-MS) (the latter primarily used for analysing stabilizer degradation). The direct comparison of the PE types revealed significant differences regarding the degradative behaviour. One main conclusion is the possible use of short n-alkanes (below 30 carbon atoms) as a quality markers in the recycling process, as unique trends in the breakdown of polymer chains were found for each PE type. Both HDPE and LLDPE showed an increase in odd numbered n-alkanes, but only HDPE showed a constant decrease in the even numbered ones. For LDPE odd and the even numbered n-alkanes were increasing during extrusion. Focusing on the effect of the added stabilizers, IF168 alone had little to no impact, whereas the presence of IX 1010 showed a beneficial influence on polymer degradation – a trend that was even intensified when both stabilizers were combined. Also, in this case differences between the three PE types could be observed. In HDPE and LDPE stabilizers were consumed during extrusion to a higher extent than in LLDPE.