Jonáš Uřičář

3D printing is an extensively used manufacturing technique that can pose specific health concerns due to the emission of volatile organic compounds (VOC). Herein, a detailed characterization of 3D printing-related VOC using solid-phase microextraction-gas chromatography/mass spectrometry (SPME-GC/MS) is described for the first time. The VOC were extracted in dynamic mode during the printing from the acrylonitrile-styrene-acrylate filament in an environmental chamber. The effect of extraction time on the extraction efficiency of 16 main VOC was studied for four different commercial SPME arrows. The volatile and semivolatile compounds were the most effectively extracted by carbon wide range-containing and polydimethyl siloxane arrows, respectively. The differences in extraction efficiency between arrows were further correlated to the molecular volume, octanol-water partition coefficient, and vapour pressure of observed VOC. The repeatability of SPME arrows towards the main VOC was assessed from static mode measurements of filament in headspace vials. In addition, we performed a group analysis of 57 VOC clas-sified into 15 categories according to their chemical structure. Divinylbenzene-polydimethyl siloxane ar-row turned out to be a good compromise between the total extracted amount and its distribution among tested VOC. Thus, this arrow was used to demonstrate the usefulness of SPME for the qualification of VOC emitted during printing in a real-life environment. A presented methodology can serve as a fast and reliable method for the qualification and semi-quantification of 3D printing-related VOC.

Poly(vinyl chloride) is widely used in the field of electrical engineering as an insulating material. Its properties are significantly dependent on the content of the plasticisers. In this work we identify plasticisers in commercially available insulated electrical wire. We quantify and qualify released hydrogen chloride and qualify volatile organic compounds at enhanced temperatures by thermogravimetric analysis, potentiometric titration, and gas chromatography-mass spectrometry system. Changes in glass transition temperatures and mechanical properties caused by enhanced temperatures are measured by dynamic mechanical analysis. The data show a significant release of hydrogen chloride above 180 °C, which has a significant effect on the mechanical properties.

The recent expansion of 3D printing caused an increase in requirements of printable materials. Since most materials with sufficient electrical properties are not suitable for 3D printing at home or are financially inaccessible, we seek better alternatives. Here, we report modification of electrical properties of commercially available stereolithography (SLA) photopolymer resin by addition of graphite powder and Fe3O4 nanoparticles. Modified resins were prepared via direct ultrasonication of resin containing up to 5 wt% of fillers. Such resins were immediately used for printing to prevent sedimentation. Printed samples were used for the measurements of DC resistivity, dielectric permittivity, and dielectric loss. The obtained data show promising trends since the resistivity decreased with higher filler content. The increase in dielectric permittivity led to increase in dissipation factor.