| Polyamide 6 (PA6) is widely used in many economic sectors with its excellent mechanical properties, wear resistance, heat resistance, electrical insulation and weather resistance. But PA6 is a flammable material of which the flames can spread rapidly because of its severe dripping, resulting in its applications being restricted seriously. Therefore, it is of important to develop flame-retarded PA6 with excellent comprehensive properties. Phosphinate flame retardants which have excellent flame retardant properties, halogen-free, low toxins and anti-migration, have been widely used in a variety of polymer.In this study,2-carboxyethyl phenyl phosphinate was used as row material to synthesize 2-carboxyethyl phenyl phosphinate aluminum(CEPPAA1) and 2-carboxyethyl phenyl phosphinic acid melamine(CEPPAME) salts. The reaction products were characterized by FTIR, ICP, XRD, and 1H-NMR. The thermal stability of CEPPAA1 and CEPPAME was investigated by TGA, and the results showed that the initial decomposition temperature of CEPPAA1 in nitrogen was 281.8℃ which was higher than the processing temperature of PA6, and the residues in 700 ℃ was 27.53%. The initial decomposition temperature of CEPPAME was 233.2℃, which can be used as flame-retardant for ABS resin etc.The CEPPAA1 was used as lame-retardant to incorporated into PA6 by melting blend, flame-retardancy of blends was gradually increased with increasing amount of CEPPAA1. When the loadings of CEPPAA1 was 15wt%, the LOI of PA6/CEPPAA1 was 27.5%. Cone calorimeter tests also showed a good flame-retardancy of PA6/CEPPAA1. Combination of CEPPAA1 and organic montmorillonite (OMMT) showed evident synergistic flame-retardancy. When adding 13wt% CEPPAA1 and 2wt% OMMT, the LOI of blend was up to 29.5%, and the structure of the char formed was more continuous and closer. Compared to the PA6/CEPPAA115, the peak heat release rate PA6/CEPPAA113/OMMT2 declined.The decomposition process and mechanism for PA6 and PA6/CEPPAA115 were explored through the research of thermal decomposition kinetics. The activation energy of PA6 was 187.13 kJ/mol while the activation energy in two different stages of PA6/CEPPAA115 were 116.43 kJ/mol and 125.97 kJ/mol.The kinetic equation of PA6/CEPPAA115 could be respectively expressed as g(α)’=[-ln(1-α)]2/3 and g(α)"=[1-(1-α)1/3]2 different with the kinetic equation of PA6. The non-isothermal crystallization behaviors of PA6/CEPPAAl were studied by DSC. The results show that adding CEPPAAl, both of the crystallinity and crystallization rate of PA6 matrix increase. The mechanical properties and rheological behaviors of blends were also investigated. The results showed that adding CEPPAA1 can maintain good mechanical properties of PA6, decreased the apparent viscosity of melting blends and improve the processing properties of PA6.The properites of PA6/CEPPAAl13/OMMT2 were investigated in detail. The tensile strength of PA6/CEPPAA113/OMMT2 was porior to that of PA6 and PA6/CEPPAA115, which showed OMMT played an important role in the reinforcement of the composites. The study of crystal behavior of PA6/CEPPAA113/OMMT2 showed OMMT acted as heterogeneous mucleation agent and the formation of y crystal was acclearated.The apparent viscosity of melting blends decreases since adding OMMT. |
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