Properties And Preparation Of Environmentally Friendly Nylon 66/Clay Nanocomposites

As nylon 66 is an important engineering plastics widely used in many areas, the study of its fire retardant property attracts more and more attention. In recent years, halogen-based flame retardants are being phased out and have been gradually replaced by environmentally friendly flame retardants. Although the flame effect of clay has been realized at present, polymer/clay nanocomposites did not pass an ignition resistance test such as UL-94 vertical burning. That because of the low thermal stability of the conventional organoclay modified with alkyl ammonium surfactants, which leading the time to ignition for polymer/organoclay nanocomposites are even shorter than polymer itself. It is also explained that only physical barrier mechanism cannot wholly prevent the heat and mass transport between the gas-phase and condensed-phase. Therefore, it is important to improve thermal stability of organoclay and introduce other halogen-free flame-retardance.A thermally stable imidazolium organoclay was synthesized to improve the flame retardancy performance of nylon 66. To further enhance flame retardancy of the nylon 66/organoclay nanocomposites, the thermally stable organoclay was modified with monomethylol melamine (MMM) before melt-compounded with nylon 66. In this thesis, nylon 66/I-clay nanocomposites were prepared by melt blending. The morphology, thermal stability, combustion behavior, of nylon 66 composites was characterized.TEM and XRD results confirmed the good exfoliation and dispersion of the organoclay in the nylon 66 matrix. The use of the thermally stable organoclay resulted in a high thermal stability of the resulting nylon 66 nanocomposites. The good dispersion of the thermally stable organoclay in nylon 66 prevented dripping of the nanocomposites during the UL-94 vertical burning test, which was against the non-flammable dripping mechanism of melamine and monomethylol melamine for nylons. The heat release rate of nylon 66 was decreased obviously with the addition of the organoclay from cone calorimetry measurements.On the basis of above studies, clay was also modified by melamine and nylon 66/M-clay nanocomposites were prepared. The systems were able to achieve V-0 rating during the UL-94 vertical burning test, showing ideal flame retardant.