Flame Retardation Of Layered Nano-Fillers/Microencapsulated Red Phosphorus On Glass Fiber Reinforced PET

Glass fiber reinforced poly(ethylene terephthalate)(GF-PET) is one of the excellent engineering plastics broadly applied in automotive industry, electronic component, structural materials, because of its good thermal, mechanical and electrical properties. However, the development and application of GF-PET are greatly limited due to its high flammability and the production of great amount of smoke during combustion. Polymer/layered nano-fillers composites have been received many researches, as the great potential of layered nano-fillers for producing materials characterized by improved flame retardancy along with superior physical properties. Nevertheless, most of these nano-fillers alone could not ensure polymer materials to pass LOI and UL94test. So much work has been done on the synergism between conventional flame retardants and nanoparticles. Moreover, metal ions can catalyze carbonization as well as suppress smoke during combustion to generate a synergistic effect. In this paper, influences of different layered nano-fillers and rare earth ions on the microencapsulated red phosphorus (MRP) flame retarded GF-PET composites are discussed and the amount of MRP is constant for4wt%.Organically modified montmorillonite with quaternary phosphonium surfactants (P-OMT) and rare ions modified organo-montmorillonite (La-P-OMT) were prepared through ion-exchange method. Thermogravimetry(TG) results indicated that these two kinds of organically modified montmorillonites exhibited excellent thermal stabilities. Effects of these two montmorillonites on the flame retardancy and thermal stability of microencapsulated red phosphorus (MRP) flame retarded GF-PET were investigated. Incorporating La-P-OMT into GF-PET/MRP. the materials showed better thermal stability and more char residues than GF-PET/MRP/P-OMT nanocomposites. When the content of La-P-OMT reached4wt%in GF-PET/MRP composites, the material could achieve UL94V-0rating, while the addition of4wt%P-OMT only leads the materials V-1rating. The residue of GF-PET/MRP/P-OMT displayed a folded structure while the residue of GF-PET/MRP/La-P-OMT showed a plainland-like structure. Lanthanum phenylphosphonate (LaPP) was successfully synthesized, and GF-PET/MRP/LaPP nanocomposites were fabricated by melt blending. LaPP showed a lamellar structure with a particle size of about200nm as well as an interlamellar distance of about1.58nm and had a remarkable thermal stability. TEM tests showed that LaPP dispersed homogenously in GF-PET/MRP system without any visible agglomeration. A slightly increase of LOI values was observed and the UL94test V-0rating was achieved by the addition of LaPP into GF-PET/MRP. The morphological structure of residues observed from SEM proved that the addition of LaPP was capable of initiating a compact and homogeneous char on the surface, which could attributed to the catalyze carbonization, physical barrier of a LaPP-enriched char protective layer and the weaken of "candlewick effect". Besides, LaPP showed good reinforcing effects on the GF-PET/MRP system. Both the tensile strength and storage module of composites were improved with the incorporation of LaPP.