Revestimentos em sementes de jarina à base de óleos ativados por jato de plasma frio

Abstract

Jarina seeds are employed in high jewelry pieces due to their similar appearance to ivory and sustainability. However, their endosperm presents vulnerability to biodegradation owing to its hemicellulosic composition and hydrophilicity. The seed composition is similar to the reported for date seeds. In order to improve their hydrophobicity, jarina seeds were coated with hydrophobic coatings by plasma jet activation. Silicone and copaiba oils and their mixture were applied on the seed surface by spray. A stable coating has been obtained upon surface exposure to an atmospheric cold plasma jet in high pressure using a plasma pen. An automatic motion system has been developed using the Arduino platform to allow the control of treatment time by the number of surface scans. Air plasma treated seeds, with no oil on the surface, became moderately hydrophilic due to the formation of a polymerized extractives layer on the surface. Hydrophobic and homogeneous films have been obtained from silicone oil, while moderately hydrophilic films presenting heterogeneities have been obtained for copaiba oil. The film obtained from the oil mixture presented an intermediate behavior with phase separation attributed to the oils incompatibility. Air plasma in silicone oil films leads to the formation of a cross-linked network. For copaiba oil, it is possible to observe the abstraction of hydrogen from alkenes and the formation of C-O-C bonds. The results of DRS UV-Vis show that the coatings do not alter the surface color; however the presence of copaiba oil results in higher opacity.