Relating Thermal Properties to Potential Interactions between Compounds in Application and Recycling, Exemplified by Model Ink-Coating Component Mixtures

The purpose of this study is to determine how certain model compounds, representing in this case ink and typical coating components, interact in increasingly complex mixtures by evaluating their response to thermal treatment. Such materials are also used in many other chemical and industrial products and processes other than printing, such that the mechanisms are universally applicable. Thermogravimetric analysis (TgA) and differential scanning calorimetry (DSC) are techniques considered here as potential tools for the analysis. Fourier transform infrared (FTIR) spectrometry is used to characterize the model compounds and to provide a characteristic of the change undergone by some model compound mixtures after thermal exposure in TgA. To visualize the thermal data so as to combine the TgA and DSC measurements into a single comprehensible observation, a representation has been devised for the specific case of material evaporation and the respective observed specific evaporation energy, whereby the specific gravimetric change (TgA) and specific energy (DSC) ratios are calculated. By adopting this combinational representation, it is possible to clarify if there are observable interactions between studied model components. It is to be supposed that the thermal behavior of solvent in a given mixture will reflect, for instance, the ease with which an ink will set and dry to form a nonsmearing print, thus improving the efficiency of this and similar such processes. Additionally, any evidence of newly formed compounds, or material loss, resulting from thermal treatment during processing may affect product performance and ultimately recyclability or waste management

Diffusion and Tortuosity in Porous Functionalized Calcium Carbonate

Calcium carbonate can be “functionalized” by use of etching agents such as phosphoric acid to create inter- and intraparticle porosity with a range of morphologies. Functionalized calcium carbonate has potential for use as a carrier for the delayed release of actives, such as drugs, plant protection chemicals, and food additives such as flavors. The drug or flavor is released slowly by permeation and diffusion. In order to measure the effective rate of diffusion within a range of morphologies, and hence gain insights into the optimum mode of functionalization, the diffusion of vanillin in ethanol is reported. Effective diffusion coefficients <i>D</i>′ were measured in a flow cell connected to a high performance liquid chromatograph (HPLC). Samples were also subjected to mercury intrusion porosimetry. The resulting percolation characteristics were inverse modeled using the PoreXpert package to generate representative void structures with estimated tortuosities. It is shown that the primary particle size of a sample was a better predictor of <i>D</i>′ calculated from the experimental diffusion curves, and also of the porosity-scaled tortuosity values, than the porosity or surface area. There was also a correlation between intraparticle tortuosity, scaled by porosity, and diffusion coefficient. The approach is validated by experimental evidence from this and related studies