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Stimulant-sensitive materials exhibit physical or chemical reversible changes in their properties as a result of environmental variables. One of these materials is thermochromic materials. Materials with thermochromic sensitivity change their color with heat exchange. For this reason, it can be used in many different fields such as security inks. Such substances decompose rapidly by being affected by weather conditions. Furthermore, the particle sizes are larger than normal pigments, and therefore, it is difficult to stabilize thermochromic dyes. Because of all these adverse conditions, thermochromic colorants must be protected before use in the ink. This protection is planned to be provided by the microcapsulation technique. The purpose of this study is to determine the thermochromic printing inks that can be stored stably by microcapsulation technique, to protect it from environmental conditions and the determination of printability parameters.

In this study, capsules with a core material of thermochromic dyeing with polyurea formaldehyde (PUF) or poly-phenolmelamine formaldehyde (PMF) shell were synthesized at appropriate pH and temperature using the appropriate solvent and mixing speed. The chemical structure and dimensions of the obtained capsules were examined by ATR-FTIR and scanning electron microscopy, respectively. The produced thermochromic microcapsules were mixed with alkyd resin and mineral oil and screen printing ink was obtained. Printability tests such as surface morphology, color, gloss and light fastness were applied.

As a result, it was determined that PMF is not a suitable encapsulation technique for thermochromic dyes under suitable conditions and eliminates thermochromic property by providing heat stability. It was found that PUF microcapsulation can be used in thermochromic dyestuff encapsulation and does not lose the thermochromic property. It has also been found that PUF microcapsules increase the lightfastness and stability of thermochromic dye ink.

This study provides experimental research on the encapsulation of a thermochromic dye and its use in ink.

The purpose of this paper is to study the tribology behavior of steel–steel contact under the lubrication of water-based drilling mud with different oleic acid-filled microcapsules as lubricant additives.

A ball-on-disc tribometer was used to evaluate the lubrication properties of the steel–steel contact. The wear tracks of the worn surfaces were observed by a scanning electron microscope.

Results show that the dependence of both friction and wear on the category of additives shares a consistent pattern. In contrast to oleic acid and empty microcapsules, oleic acid-filled microcapsules achieve the best tribological performance which is related to the lubricant effect of oleic acid and the isolation and rolling abilities of microcapsules.

This study provides a helpful method of encapsulated lubricant additives to prolong lubrication performance for steel–steel contact.

This study has applied microcapsules to improve the tribological properties of drilling mud.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2019-0320/

The purpose of this work was to prepare a catalyst-free microcapsules as self-healing agent in an automotive clearcoat to improve the scratch resistance of coatings.

In this research, microcapsule with isophorone diisocyanate (IDPI) core and polyurethane shell were prepared and used in self-healing coatings. Microcapsules synthesised were characterised by thermal gravimeter and infrared spectra. The microcapsules were dispersed in an acrylic-melamine clearcoat, and the scratch resistance was evaluated.

The triplex product and the formed polyurethane bonds were confirmed by thermal gravimeter and infrared spectra. In addition, smooth spherical particles with a diameter of 1.5 to 1.7 micronmeters were observed by a scanning electron microscope. The microcapsules dispersed in an acrylic-melamine clearcoat increased the scratch resistance of coatings. Also, the self-healing feature of those coatings was proved.

The size of microcapsules can affect its dispersion in the clearcoat and consequently affect the properties of the cured films.

The self-healing coatings are interested for many industries such as building and automotive industries. The reported data can be used by the formulators working in the R & D departments.

Self-healing systems are considered as one of the smart coatings. Therefore, the developing of its knowledge can help to extend its usage to different applications.

The application of microcapsules in the coating as healing agents is a great challenge, which has been hardly investigated so far. In the current research, the effect of polyurethane-IDPI microcapsules in an automotive clearcoat as a self-healing coating was investigated.