Light guiding is used to direct light from an emitting source to a different location. It is frequently realized through a clad–core structure with a difference in the refractive index of the materials. This paper explores the possibility of combining a fluoropolymer (THV) film of low refractive index, serving as a cladding layer, with a polycarbonate (PC) core, via injection molding. Pristine THV lacks adherence to the PC. However, when treated with ${\mathrm{O}}_2$ plasma prior to overmolding, bonding can be established that was quantified in peel tests. The effect of this surface treatment was further investigated by adjusting the plasma treatment duration and time to overmolding. Furthermore, parameter studies comprising the four molding parameters, namely packing pressure, injection speed, melt temperature, and mold temperature, were performed. Numerical injection molding simulations assessed the prevailing temperatures at the PC–THV boundary. Consequently, the temperature–time integral could be calculated and linked with the measured peel strengths by fitting a proportionality constant. While the plasma treatment duration showed minor influence, the activation diminished with time, halving the measured peel loads within 24 h. The adhesion was experimentally found to increase with a lower packing pressure, faster injection speed, and higher melt and mold temperature. Those same molding relations influencing the peel loads were also found with the temperature–time integral when scaled by the proportionality constant in the simulations (${\mathrm{R}}^2=85\%$). Apparently, adhesion is added by molding settings which promote higher interface temperatures that prevail for longer. Hereby, the faster injection speed increases the melt temperature through shear heating. A higher packing pressure, in contrast, presumably increases the heat transfer at the PC–THV interface, accelerating the cooling. The measured peel loads were 0.3–1.6 N/mm for plasma-treated samples and nearly zero for pristine THV.

Multi-layer films are one of the most challenging classes of polymer waste for recycling, as they consist of a mixture of constituent materials like polyethylene (PE), polyamide 6 (PA6), and ethylene vinyl alcohol (EVOH). This study investigates the characterization, washing, and mechanical properties of recycled blends derived from such multi-layer films. Raman spectroscopy and Differential Scanning Calorimetry (DSC) were used to characterize the individual components in single- and multi-layer films, and distinct properties of LDPE, LLDPE, PA6, and EVOH were observed. Mechanical properties enhanced by proper shredding, washing procedures, and multiple combinations of polyethylene blends were investigated to optimize the mechanical characteristics of the recycled materials, especially strain at break. Additionally, the shrinkage behavior of the recycled films was compared to commercial shrink films, demonstrating their potential for use in industry packaging applications. These results highlight a more sustainable possibility for multi-layer packaging applications.

The microstructure of polymer blends significantly influences their mechanical properties, with performance primarily determined by blend composition, morphology, and processing conditions. This study examines the mechanical properties, morphology, and microstructure of recycled polymer blends composed of low‐density polyethylene (LDPE), linear low‐density polyethylene (LLDPE), polyamide 6 (PA6), and ethylene vinyl alcohol (EVOH), with and without compatibilizers: polyethylene grafted with acrylic acid (PE‐AA), 2,2′‐(1,3‐Phenylene)bis(2‐oxazoline) (1,3‐PBO) and 2,2′‐(1,4‐Phenylene)bis(2‐oxazoline) (1,4‐PBO). Tensile testing shows that a PE‐AA and 1,4‐PBO combination enhances strain at break by 50%, suggesting improved interfacial adhesion. The blend with partial replacement of LDPE by LLDPE exhibits the highest strain at break (increased by 125%) and the narrowest droplet size distribution. Scanning electron and photo‐induced force microscopy confirm a droplet‐matrix morphology, with PA6 forming the core and EVOH the droplet shell. Mechanical performance correlated more strongly with droplet count than with droplet size. Raman spectroscopy and photo‐induced force microscopy detected spectral changes, indicating chemical interactions contributing to improved mechanical properties. Differential scanning calorimetry did not indicate any significant effects of compatibilizers on phase miscibility. These findings highlight the role of linear low‐density polyethylene in optimizing mechanical properties.