Yağ temelli bağlayıcı üretimi için trigliserid yağların modifikasyonunda kolay bir yöntem

Triglyceride oils, which are the ester products, formed from one molecule of glycerol and three molecules of fatty acids. They are able to undergo chemical reactions through their functional sites. As being natural and renewable resources they have a great importance for industrial applications such as coatings, soap, surface active materials, chemical intermediates and oleoresinous binders. On the other hand, since their film properties have some deficiencies in organic coating applications, they need to be improved with this respect. In this context, a number of studies on the modification of triglyceride oils were performed. In these studies macromer and macroinitiator methods have been developed to enhance the film properties. Macromer method was performed by inserting a vinyl functionality to the oil moiety and final macromer were copolymerized with vinyl monomers such as styrene. In the macroinitiator method an initiator molecule such as functionalized azo initiator was inserted into the oil moiety. The polymerization in the presence of macromer or macroinitiator was carried out both free and controlled/living radical polymerization such as nitroxide mediated radical polymerization (NMRP), reversible addition-fragmentation chain transfer polymerization (RAFT). In addition to vinyl monomers, non-vinyl monomers such as methylolated abietic acid, diisocyanates, alkoxysilane and benzoxazine were used for triglyceride oils modifications as well in previous studies. In the present study, benzoxazine and 3-aminopropyltriethoxysilane were used together to develop an easier way for modification of triglyceride oils. Benzoxazines are preferred for a wide range of applications due to their unique properties such as high char yield, relatively high Tg, low water absorption, no by-products during curing, low flammability, molecular design flexibility and no requirement for curing strong acid catalysts or additives. On the other hand, polybenzoxazines have some disadvantages such as high curing temperature, brittleness and processing conditions. By combining benzoxazine structures with additional functionality, polymers, inorganic materials and nanostructures is the most common method to overcome these disadvantages. In this context, silane coupling agents are extensively used due to be commercially available, highly reactive to the hydroxyl functional surfaces and to have wide variety of functional groups which brings design flexibility. In this way, by establishing chemical bonds between the soft organic and the hard inorganic species properties can be improved. The steps of the process as follows; (i) preparation of partial glyceride (PG), (ii) preparation of enhanced partial glyceride (PGE) (iii) synthesis of benzoxazine functional silane (Bz-Si), (iv) preparation of film samples by the mixing (ii) and (iii) (Bz-Si/PGE), (iv) curing of the films through thermal and sol-gel reaction, v) determination of film properties. As mentioned above, preparation of film samples is done by using benzoxazine functional silane and enriched partial glyceride. Because producing mono- and diglyceride with high yield by glycerolysis or esterification reactions is impossible due to limited solubility of triglyceride and fatty acids. Final product is obtained as the mixture of mono-, di- and triglycerides. Therefore, by using solvent extraction method enhanced partial glyceride is obtained to increase the yield of individual partial glyceride. The characterization of the samples were identified by fourier transform infrared spectroscopy (FT-IR). Synthesis of Bz-Si, combining to Bz-Si with PGE, crosslinking reaction and thermally activated curing of Bz-Si/PGE via ring-opening polymerization of benzoxazine moiety were confirmed with respect to FT-IR results. Thermal analyses of the samples were done by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Cured Bz-Si/PGE film samples (CF(Bz-Si/PGE) gave higher decomposition temperature at both 5% and 10% weight loss compared to Bz-Si and also classical urethane oil and benzoxazine modified oil which were used in previous study. Additionally, no melting behavior of cured Bz-Si/PGE at DSC results indicates that sol-gel reaction between oil moiety and silane group occurred and high degree of crosslinking restricts the molecular motion and also gives high thermal stability to the final product. In the end, samples with acceptable film properties (with respect to American Society for Testing and Materials (ASTM) and German Institute for Standardization (DIN) procedures) , which are highly important for an organic coating material,were achieved by this modification.