Study On Glass-fiber Reinforced Poly(Butylene Terephthalate) Preparation Technology And Synergistic Flame Retardant Modification

Firstly, process parameters, screw combination and synergistic additives and other aspects were considered, then used a three-screw extruder to prepare glass fiber reinforced PBT (GF-PBT) composites. The results showed that when the glass-fiber content is less than 35wt%, the mechanical properties of GF-PBT composites increased with glass-fiber content increases. Due to "wick effect" exists, the limiting oxygen index (LOI) of composites less than pure PBT. The extrusion temperature for glass-fiber reinforced PBT preparation, should be controlled at 225～240℃. Silicone resin has the effect of toughening functions in the GF-PBT system. Screw combination and screw speed have greater influence on the material properties, strong shear screw combination mode at high speed is not conducive to the production of glass-fiber reinforced composites.Secondly, melamine cyanurate (MCA) and aluminum diethyl phosphinate (ADP) were employed as a flame retardant to prepared flame-retardant reinforced GF-PBT composites(FR-GFPBT). The results show that when ADP:MCA=1:1, the amount was 20wt%, the LOI value of composite was 32.4%, UL94 V-0 levels. The initial decomposition temperature of FR-GFPBT composites decreased by 34℃,12℃ and 32℃ after add MCA, ADP and MCA/ADP (complex flame). MCA does not promote charring effect; while when ADP and MCA/ADP were added, the carbon residue of composites increased 3.4% and 4.8% than the theoretical amount of carbon residue, which indicating that the two flame retardants have good synergy in the system. The heat release rate (HRR), total heat release (THR) and effective heat of combustion (EHC) of FR-GFPBT composites has decreased, but the smoke release rate peak (pSRP) is somewhat elevated, indicating that the two have a synergistic flame retardant effect, but no smoke suppression effect. After adding complex flame retardant,tensile strength, flexural strength and impact strength can maintain the original 63.9%, and 81.9% and 64.56%.Finally, choose silicone resin with melamine cyanuric acid (MCA), diethyl aluminium phosphate (ADP) and ADP/MCA compound, respectively, to prepare glass fiber reinforced flame retardant PBT composite material. The results show that silicone resin compound used with ADP or MCA, it can slight increase the thermal stability of the composite material, promote char formation. Average mass loss of the composite material (aMLR), HRR and THR have different degrees decreased, which indicating the silicone resin can slow bu(?)g rate, to reduce fire hazard. Increased the final amount of carbon residue indicated that(?)silicone resin not only can reduce the degree of combustion, but also prompted some matrix cross-linked into charcoal for condensed phase flame retardant. At high magnification of SEM, separately added silicone resin compositematerial, which glass surface partially covered some microspheres, and the microspheres have an uniform size, a regular shape. It can not effectively reduce the "wicking." After the silicone resin compound with MCA, the tensile strength, flexural strength and impact strength were increased by 19.9%,2.5% and 2.4%. When it complex with ADP, tensile and flexural strength of the composites decreased 3.2% and 17.9%, while the impact strength increased by 10.7%. When the silicone resin, ADP and MCA complex together, the tensile and impact strength increased by 9.0% and 7.0%, while the bending strength decreased 5.4%.