The synthesis of BFTDA (3) was carried out according to the synthetic route depicted in Scheme 1.
The epoxy nanocomposites were named R-v-y, where x represents the added organoclay (that is bentonite, or APUA/ BFTDA functionalized bentonite) and y represents the overall amount of nanofiller in the sample (3 or 5%wt).
In order to pursue an efficient and mild synthetic approach, the attention was directed toward the synthesis of a novel similarly N-rich triazine derivative, such as 6-(4-butylphenyl) - 1,3,5-triazine-2,4-diamine (BFTDA) (Fig.
Once the organic modifiers were successfully obtained, two organophilic clays, based on acidified BFTDA and APUA and labelled Bento-BTFDA and Bento-APUA respectively, were synthesized with an ion exchange process starling from pristine bentonite.
and considered to occur even in the organomodified clays, and it was thus evaluated that the organic content is 9.0%wt in Bento-BFTDA and 10.9% wt in Bento-APUA, corresponding to 0.370 mmol of BFTDA and 0.394 mmol of APUA for 1 g of organoclay (mmol/g), respectively (Table 2).
Furthermore, it is worth noting that all the organoclays containing samples display an inorganic clay solid residue at the end of the TGA run, whose amount well compares with the weight fraction of nanofiller in the feed, taking into account also the degradation of the organic fractions due to APUA and BFTDA. As expected, no residue was detected for the plain resin NEAT (Table 3 and Fig.
The addition of Bento-BFTDA nanofillers, both at 3 and 5 wt%, leads to a significant improvement of the flame retardant properties (pHRR, FPI and FIGRA) of the nanoeomposites if compared with plain R-Bento, but they are still worse than plain resin (NEAT): the N-rich BFTDA is not enough to compensate the negative influence that the clay imparts in terms of flame behavior.
Two new organoclays were prepared from the modification of bentonite with nitrogen-based organic compounds BFTDA and APUA and used for the preparation of epoxy resin nanocomposites.