synthesis and characterization of thermally stable and fire resistance polymer/mg(oh)2 nanocomposites based on phosphorus containing aromatic polyamide

Aromatic polyamides due to their special structure and hydrogen bonding have flame retardancy effect [2]. in the other hand for boosting flame retardancy effect it needs to add some additive such as nanoparticles and phosphorus compounds. [4]one of the phosphorous molecules is 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (dopo) which has attracted researchers’ attentions in developed countries. analyses have shown dopo had flame retardancy effect in dense phase by producing a new polyphosphoric acid layer in material [1].among the nano particle magnesium hydroxide has flame retardancy effect by the mechanism dihydroxylation process [3].although nanoparticles have unique properties but they don’t have well dispersity in polymer matrix. in the other hand nanoparticles need to organo modification.in this project, for preparation of polyamide/mg(oh)2 nanocomposites, a new polyamide containing dopo structure (pa) segment was synthesized by yamazaki method. for this reason, a new dopo based dicarboxylic acid was synthesized in two steps reaction. the structure and purity of polyamide were investigated by using ft-ir, 1h-nmr and xrd analysisin other way, the synthesized mg(oh)2 nanoparticles was organically modified with dopo based dicarboxylic acid (mmg)and its structure was investigated by ft-ir, fe-sem, xrd, tga analysis. modification causes better dispersity in polymer matrix.polyamide nanocomposites were prepared from pa and appropriate amounts of modified mg(oh)2 nanoparticle via solvent casting method. structure and morphology of modified mg(oh)2 nanoparticles were evaluated by ft-ir, xrd, fe-sem and the results indicated that nanoparticles were dispersed uniformly in the polymer matrix. the polymer and organo modified nano particle have interaction by hydrogen bonding and between nano particles, modifier and polymer and π-π stacking between polymer and modifier.the thermal stability of the synthesized polyamide and nanocomposite was investigated by using tga analysis in n2 and air atmospheres, and also flame retardancy of the new materials was evaluated by microscale combustion calorimetry (mcc).the results indicated that the presence of dopo structure and modified mg(oh)2 nanoparticles had good effect on the combustion resistance of polyamide and corresponding nanocomposites.