![]() Assessment of their resistance to specific chemical agents was performed according to the procedure described in the ISO 2836:2021 standard. Hence, two thermochromic inks with different activation temperatures (one being cold and the other being body-heat activated), printed on two food packaging label papers that differ in their surface properties were chosen to be tested. Given the fact that prints can be found in different environmental conditions during their lifetime, in this work, thermochromic prints were exposed to the action of UV radiation and the influence of different chemical agents in order to simulate different environmental parameters. Thermochromic inks, however, are known to be sensitive materials to the influence of UV radiation, heat fluctuations, and various chemical agents. These inks are also gaining more attention as part of textile decorations and can also be found in some artistic works obtained with thermochromic paints, due to their ability to change color when exposed to heat. Thermochromic inks, also known as color changing inks, are becoming increasingly important for various applications that range from smart packaging, product labels, security printing, and anti-counterfeit inks to applications such as temperature-sensitive plastics and inks printed onto ceramic mugs, promotional items, and toys. While the performance of the biobased coating was subpar, no evidence linking its degradation to the presence of renewable monomers was found, suggesting that the creation of a sufficiently durable and renewable exterior coating will be possible Their degradation was followed directly by gloss retention and different mechanisms were revealed using FTIR, µ-hardness and film thickness measurements. Series of prototypes with a wide variety of properties were then subjected to accelerated weathering tests. A structure-property relationship concerning the coating glass transition temperature and visco-elastic behaviour of the coating was furthermore established for a series of renewable monomers and contrasted with petroleum based equivalents. The transformation of its aldehyde and its reactivity was studied in terms of catalytic activation and through a series of copolymerisations which revealed the influence of the reaction conditions on the composition of the product. Vanillin was chosen as a possible extension to the range of rigid, biobased monomers for polyesterification reactions. This presents two challenges: The limited availability of monomers which provide rigidity in the resin structure and the relationship between the resin composition and its weatherability. In order to extend the possible use of the biobased product to exterior applications, an improvement of its resistance to humidity and UV radiation is crucial. Within the Sorago project, a fully biobased resin for interior coil coatings has recently been proposed on the market (Estetic® Bio Air, Arcelor Mittal). Aliphatic polyesters based on renewable resources have already started to replace traditional products. Moving away from petroleum and towards biobased materials not only leads to greater sustainability and lower dependence on diminishing fossil resources, but can also catalyse the discovery of new properties. Photodegradation initiates at degradation-susceptible hydrophilic domains spreading to surrounding areas contiguous with the initiation site. These hydrophilic domains, which are energetically preferred, comprise polar, unreacted and partially polymerized molecules, chromophores, and other additives. The model proposes that nanosize “hydrophilic” domains are dispersed randomly with the highly crosslinked units. A conceptual model is proposed to explain the inhomogeneous degradation mode. Results indicated that photodegradation of crosslinked coatings is a spatially localized (inhomogeneous) process in which nanometer-sized pits are initially formed these pits deepen and enlarge with exposure. Atomic force microscopy and Fourier transform infrared spectroscopy were used in following nanoscale physical and chemical degradation during exposures. Three model crosslinked coatings were exposed in various ultraviolet environments. ![]() The objective of this study is to assess the degradation modes of crosslinked coatings exposed to photolytic environments.
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