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The current efforts in moving closer towards a circular plastics economy puts massive pressure on recycled plastics, especially recycled polyethylene (rPE) and recycled polypropylene (rPP) to enter new markets. Their market penetration remained low so far, despite PE and PP constituting the largest share of plastic wastes. However, with the current imperative of more circularity comes a new focus on performance of recyclates. Hence, a detailed understanding of composition and structure–property relationships of post-consumer recyclates has to be developed. Five recycling companies from the Austrian and German markets were asked to supply their purest high-quality rPE and rPP grades. These were characterized by differential scanning calorimetry (DSC), thermo-gravimetric analysis (TGA), and Fourier-transform infrared (FTIR) spectroscopy, and micro-imaging. Technological characterization included density measurements, determination of the melt flow rate (MFR), and Charpy impact testing. All recyclates contained diverse contaminants and inclusions ranging from legacy fillers like calcium carbonate to polymeric contaminants like polyamides or polyolefin cross-contamination. The overall amount, size, and distribution of contaminants varied significantly among suppliers. Furthermore, first structure–property relationships for polyolefin recyclates that link inorganic content and polymeric purity with density and impact performance could be derived.

The adsorption kinetics of self-assembling n-alkyl thiol films on poly cry stalline gold substrates was studied in situ by optical second harmonic generation (SHG). The relation between the SHG signal change and the thiol coverage was established by comparison with ex situ X-ray photoelectron spectroscopy measurements. We find that the temporal dependence of the adsorption is well described by Langmuir adsorption kinetics. The source of the SHG signal is found to be linearly related to the nonlinear susceptibility of the adsorbate-substrate interaction. Experiments with chain lengths ranging from 1 to 22 showed, that the saturation coverage for thiols longer than hexanethiol is equal.

Nonthermal in vitro ablation of bovine neural tissue by using laser-induced optical breakdown generated by ultrashort laser pulses, with durations from 100 fs to 35 ps and pulse energies of up to 165 µJ, has been investigated. The experiments were performed at wavelengths ranging from 630 to 1053 nm by using a femtosecond Ti:Sapphire laser, a femtosecond dye laser, and a picosecond Nd:YLF laser system. Tissue ablations have been achieved by focusing the laser beam on the surface of the tissue, to a spot diameter of 5-20 µm, resulting in the generation of a microplasma. Laser pulses from the Ti:Sapphire laser with 140 fs duration showed a two times higher efficiency of ablation than the longer 30 ps pulses from a Nd:YLF laser with an identical pulse energy. At pulse energies of 140 µJ, single pass excisions deeper than 200 µm were generated by the 140 fs pulses. In addition, the fluence at threshold of the ablation was found to be reduced for shorter pulse durations. For 3 ps laser pulses at 630 nm, we measured the fluence at threshold to be about 5.3 J/cm 2 ; for 100 fs pulses from the same laser the experimental threshold was at 1.5 J/cm 2. Histopathological examinations and scanning electron micrographs confirm the high quality of the excisions. No sign of significant thermal damage was observed.

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