Vertex 80 ftir spectrometer

The NIR-photorheology measurements were performed on an Anton Paar MCR 302 WESP with a P-PTD 200/GL Peltier glass plate and a disposable PP25 measuring system, which is hyphenated with a Bruker Vertex 80 FTIR spectrometer, equipped with NIR optics. A detailed description on the experimental set-up and the underlying method can be found in literature.^{9 (link)} For each measurement 150 μL of sample was applied between the glass and steel parallel plates at 20 °C with a gap of 200 μm. The formulations were oscillated with a strain of 1% and a frequency of 1 Hz. As UV light source an Exfo OmniCure LX 400 spot curing system was used and the light was projected via a dual-waveguide onto the glass plate with the sample (LED with 400 nm, 0.05 mW cm⁻² on the surface of the sample). During the experimental run, the storage modulus, loss modulus and normal force were measured via rheology. From NIR data collected during the measurements the double bond conversion (DBC) of the acrylate double bonds can be obtained in situ. The data were collected for 65 s in the dark and then during interrupted irradiation of the sample consisting of intervals with 6 s light impulses and 30 s periods in the dark. The data from the end of the 30 s intervals were plotted into a graph.

Ultraviolet-visible (UV-Vis) and Fourier transform infrared (FTIR) spectra were recorded from 0.375 to 3.30 μm and from 3.30 to 12.40 μm using a PerkinElmer LAMBDA 950 UV-Vis spectrometer and a Bruker VERTEX 80 FTIR spectrometer, respectively. Thin films were prepared by spin-coating a chlorobenzene solution (10 mg ml⁻¹) of the polymer onto NaCl substrates at 800 rpm for 60 s. Solution spectra were recorded from 0.375 to 2.25 μm using a Cary 5000 UV-Vis-NIR spectrophotometer in dry 1,2-dichlorobenzene at room temperature.