Abstract
The fireproofing study of polyamide 11 (PA11), a bio-based polyamide synthesized from castor oil and marketed under the trade name Rilsan® is presented. As an interesting perspective, FR can be chemically linked to the PA backbone. In this way, we achieved the synthesis of a dicarboxylic acid from DOPO cycle (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide). This phosphorus diacid derivative was able to react by polycondensation to give rise of new copolyamides (coPA) bearing phosphorus moieties attached to the PA backbone with 15,000–30,000 g/mol as molar masses. The amount of phosphorus and the viscosity of the final PA were optimized. Thermal properties such as thermogravimetry analysis (TGA) or differential scanning calorimetry (DSC) were evaluated and were shown crystallinity and degradation typical of linear PA11. UL94-V0 ranking coupled with high Oxygen Limit Indexes (LOI = 40) were also obtained. Pyrolysis-combustion flow calorimeter (PCFC) and cone calorimeter were performed to understand the mode-of-action of the new phosphorus-containing FR used to obtain self-extinguishing bio-based PA11. Lastly, the preserving of mechanical properties was highlighted.