Specific nano- and micro-scale morphologies of composites can affect the resulting optical and UV reflectivity of the materials. One example is “Vantablack ^® ” made from aligned carbon nanotubes (CNTs) with 99.96% absorption. A similar material with CNTs grown on surface-activated aluminum (CNTs/sa-Al) even yielded 99.995% absorption, one order of magnitude higher than Vantablack®. On the other hand, fresh snow reflects 90% or more of the incident electromagnetic radiation with wavelengths between 400 and 1,000 nm. The reflectivity of snow originates from multiple scattering in the porous morphology made of snow grains. Taking these complex morphologies as inspiration, CFRP epoxy composites with different types, sizes, shapes, and amount of nanoparticles are prepared and compared regarding their optical and ultraviolet (UV) reflectivity. Increasing the reflectivity in the near and far UV may be beneficial for the durability of the epoxy composites, but selective higher or lower reflectivity in certain wavelength ranges may also yield tailored visual effects. Results from different processing approaches with selected nanoparticles are presented and discussed.

The use of two wavelengths to activate different photoreactions in a resin system has recently attracted much attention in the scientific community. Here, wavelength orthogonal photochemistry was used to spatially control the curing kinetics of the thiol-ene photopolymerization reaction. Antagonistic photochemical control is successfully applied to thiol-ene polymerization. In the investigated resin (pentaerythritol-tetrakis(3-mercaptopropionat); PETMP and triallyl-triazine-2,4,6(1H,3H,5H)-trione; TATO) system, radical curing is activated by a type II photoinitiator at 450 nm, while light at 365 nm is used to photorelease a base, resulting in an inhibition of the curing reaction. The antagonistic nature of these photoreactions is demonstrated in laser writing with minimum feature sizes below 0.5 µm as well as in grey scale patterning experiments. Spatially controlled inhibition and retardation of the thiol-ene curing reaction on a sub-micron scale have potential applications in advanced large area lithography, e.g. interference lithography.

This study examines the intrinsic optical enhancements of carbon fiber-reinforced polymers (CFRPs) achieved through the integration of magnesium oxide (MgO) nanoparticles, as well as Mg/MgO and titanium dioxide (TiO₂) thin films onto carbon fibers. Integration was performed by quasi-continuous electrophoretic deposition (EPD) and physical vapor deposition (PVD), respectively. Employing a customized electrophoretic cell, EPD facilitated uniform MgO nanoparticle deposition onto unsized carbon fibers, ensuring stable nanoparticle dispersion and precise fiber coating. As a result, the fibers exhibited increased ultraviolet (UV) reflectance, largely attributed to the optical properties of the protective MgO layer. In parallel, PVD enabled the deposition of Mg/MgO and TiO₂ thin films with tailored thicknesses, providing precise control over key optical parameters such as reflectivity and interference effects. Mg/MgO coatings demonstrated high UV reflectivity, while TiO₂ layers, with their varying refractive indices, generated vibrant colors in the visible (Vis) range through thickness-dependent light interference. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) assessed the quality, thickness, and uniformity of these thin films, and UV/Vis spectroscopy confirmed the influence of deposition parameters on the resulting optical performance. Post-lamination analyses revealed that both EPD and PVD modifications significantly enhanced UV reflectivity and allowed for customizable color effects. This dual strategy underscores the potential of combining EPD and PVD to develop advanced CFRPs with superior UV resistance, decorative optical features, and improved environmental stability.

The integration of natural fibre thermoplastic composites, particularly those combining flax fibres with polypropylene, offers a promising alternative to traditional synthetic composites, emphasising sustainability in composite materials. This study investigates the mechanical properties of flax/polypropylene composites manufactured using flashlamp automated tape placement and press consolidation, individually and in combination. Tensile, compression, three-point bending, and double cantilever beam tests are utilised for comparing these manufacturing processes and the mechanical performance of the resulting composites. The microstructure of the tapes is investigated using cross-sectional microscopy, and the thermophysical behaviour is analysed utilising thermogravimetric analysis and differential scanning calorimetry. The temperature during placement is monitored using an infrared camera, and the pressure is mapped with pressure-sensitive films. The natural fibre tapes show a good aptitude for being manufactured with automated tape placement. The tensile performance of tapes manufactured with automated tape placement is close to that of press consolidated samples. Compression, flexural properties, and the mode I fracture toughness critical energy release rate all benefit from a second consolidation step.

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.