Synthesis of new aromatic polyamides containing a-amino phosphonate with high thermal stability and low heat release rate Mohsen Hajibeygi 1 • Hosein Jafarzadeh 1 • Meisam Shabanian 2 • Henri Vahabi 3 Received: 9 November 2018 / Accepted: 9 May 2019 Ó Akade ´miai Kiado ´, Budapest, Hungary 2019 Abstract The new aromatic polyamides containing a-amino phosphonate were synthesized from phosphorus-based dicarboxylic acid 4 and various aromatic diamines by direct polycondensation reaction. Dicarboxylic acid 4 was successfully synthesized from trimethyl phosphite, 4-aminobenzoic acid and terephthaldehyde via a three-component reaction. The polymerization reaction produced the polyamides 6a–f with high yield and desirable inherent viscosities. The thermal properties of the all samples were investigated by thermo-gravimetric analysis (TGA). The TGA results in N 2 exhibited the 10% mass loss temperatures (T 10 ) in the ranges of 324–345 °C, while the T 10 resulted from thermo-oxidative degradation were higher than those. The main data obtained by microscale combustion calorimetry revealed acceptable combustion properties such as very low peak of heat release rate for the synthesized polyamides 6a–f. The all of the results indicated that these polyamides can be potentially utilized as additive for improvement of thermal resistance and combustion behavior of thermoplastic materials. Keywords Polyamide Á Thermal properties Á Combustion behavior Á a-amino phosphonate Á Polycondensation Introduction Aromatic polyamides, which are usually called as aramids classified as high-performance materials, have been received notable attention due to their unique properties such as thermal stability, flame retardancy, mechanical properties and chemical resistance [1]. According to liter- ature results, the chemical structure of aramids is very effective on their thermal stability, flammability and the mechanical strength [2]. These excellent properties usually due to the high average bond energy as well as directional intermolecular interactions such as hydrogen bonds between amide functional groups as well as the rigidity of the polyamide backbone, due to the presence of aromatic segment conjugated with amide groups provide the mate- rials with high cohesive energy [3]. However, aromatic polyamides lack the properties use- ful for fabrication into highly used products due to high glass transition and melting temperature along with poor solubility in common solvents [4, 5]. To overcome these, the polyamide structures have been modified with intro- duction of aliphatic and/or aromatic non-coplanar seg- ments, antisymmetric structures instead of symmetric structures, aliphatic, aromatic and heterocyclic bulky pen- dent groups, flexible groups and highly polar functional groups into their rigid polymer backbone [6–9]. Phosphorus-containing functional groups have been proposed to improve the polyamide properties such as organosolubility along with thermal stability and fire retardancy [10–12]. Various monomers such as dicar- boxylic acids and diamines containing phosphorus groups have been successfully synthesized and used for prepara- tion of thermally stable and fire retardant polyamides [13–16]. Moreover, chemical functional groups containing phosphorus have been also incorporated into the polymer chains for increasing the adhesion properties of polymers & Mohsen Hajibeygi mhajibeygi@khu.ac.ir; mhajibeygi@gmail.com 1 Faculty of Chemistry, Kharazmi University, Tehran 15719-14911, Iran 2 Faculty of Chemistry and Petrochemical Engineering, Standard Research Institute (SRI), P.O. Box 31745-139, Karaj, Iran 3 Laboratoire MOPS E.A. 4423, Universite ´ de Lorraine, 57070 Metz, France 123 Journal of Thermal Analysis and Calorimetry https://doi.org/10.1007/s10973-019-08383-6