Influence of maleic anhydride-grafted EPDM and flame retardant on interfacial interaction of glass fiber reinforced PA-66

In this paper, the effects of melamine polyphosphate flame retardant (MPP-FR) and maleic anhydride-grafted EPDM (MA-EPDM) on the interfacial interaction of PA66/GF were investigated by means of scanning electron microscopy (SEM), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), rheological behavior and mechanical properties. The experimental results demonstrate that MPP-FR and MA-EPDM could effectively improve interfacial interactions between the PA66 and GF. Based on SEM, good interfacial adhesion between PA66 and GF in PA66/GF/FR and PA66/GF/FR/MA-EPDM composites was observed, however, MPP-FR destroyed the PA66 matrix. DMA results show that MPP-FR increased glass transition temperature (Tg) and storage modulus, and lower tan δ, while MA-EPDM showed a little effect on them in PA66/GF/FR/MA-EPDM composite compared with PA66/GF/FR. MPP-FR made PA66 crystallization temperature and the activation energy of the macromolecular segments transport increase clearly, and enhanced crystallization degree of PA66 according to DSC results. These results demonstrate MPP-FR presented the nucleate effect for the crystallization of PA66. At the low shear rate, MPP-FR and MA-EPDM obviously enhanced apparent viscosities of the composites. This is attributed that MPP-FR improved the interfacial interaction of the composites, and MA-EPDM promoted the formation of high molecular weight structures by the reactions between MA and amine groups. All results in this paper were consistent, and showed the good interaction among PA66, GF, MPP and MA-EPDM, which were proved by the mechanical properties of the composites.