Synthesis Of N-ethyl Triazine-piperazine Copolymer And Properties Of Intumescent Flame Retardant Polypropylene

Traditional intumescent flame retardant systems have many shortcomings such as easy to moisture absorption, poor thermal stability and easy migration, which has caused the restriction of practical application of intumescent flame retardant system. In this paper, a novel triazine macromolecular designed as charring-foaming agent was synthesized in order to improve the water resistance property of intumescent flame retardant system to expanding its application in practical. A new IFR system mainly consisted of new charring-foaming agent, ammonium polyphosphate (APP) and SiO2was used for flame retardant polypropylene (PP).Triazine ring containing compounds have been considered as effective charring-foaming agents in intumescent flame retardant systems. In this paper, a hydropholic triazine macromolecule, called as N-ethyltriazine-piperazine copolymer (ETPC), was synthesized by three step reactions. The synthesis reaction use cyanuric chloride, ethylamine and piperazine as raw materials, a mixture of acetone and water solution as dissolvant and NaOH as acid-binding agent. Its chemical structure was analyzed by FT-IR, I3C NMR spectroscopy and elemental analysis. The thermal degradation and hydrophobicity of ETPC were assessed by thermogravimetric analysis (TGA) and contact angle measurement, respectively. The synthetic product was insoluble in common organic solvents, which showed that ETPC has good solvent resistance. TGA data revealed that ETPC had high thermal stability and a good propensity for char formation, its initial decomposition (based on5wt%loss) temperature was up to331℃, and its char residues at700℃amounted to21.3wt%. The contact angle value of ETPC was107°, which showed that ETPC was hydrophobic, because one of the chlorines in cyanuric chloride was replaced by ethyl, that is, a hydrophobic group.Moreover, the novel intumescent flame retardant (IFR) consisting of ETPC, ammonium polyphosphate (APP) and silica was used in polypropylene (PP) to solve flame retardance and water resistance. Based upon the result of limiting oxygen index (LOI) and vertical burning (UL-94) tests, IFR-PP composite has good flame retardant property. When the loading of IFR was24wt%, treated IFR-PP composite with1.6mm thickness can still pass UL-94V-0level and its LOI value reaches33.5%, which can satisfy the requirements of flame retardant and water resistance for materials. The mechanical properties test results show that the added of IFR has little effect on the mechanical properties of the material.Contact angle test of new IFR and X-ray photoelectron spectroscopy (XPS) analysis of IFR-PP composite results showed that the contact angle of new IFR is103°, which exhibit some hydrophobic properties, mainly due to the join of ETPC. ETPC can modify APP by surface coating. XPS result also proves this conclusion. Hot water treatment result shows that the mass loss rate of treated IFR-PP composite is very low. When the novel IFR loading was24wt%, the mass loss rate of IFR-PP composite with1.6mm and3.2mm thickness are0.26%and1.08%, respectively.According to cone calorimeter (CONE) test, the loading of novel IFR can obviously decrease the heat release and smoke release parameters (heat release rate (HRR), total heat release (THR), smoke production rate (SPR) and total smoke production (TSP)). A great quantity of high quality char residue was generated, which is a good explanation of the efficient flame retardant of novel IFR. TGA results agree with the results of CONE test, both of them reflect high thermal stability and char-forming ability of IFR-PP composite. CONE and TGA results also show that the treated IFR-PP composite still retain high thermal stability and char forming ability.After CONE test, both IFR-PP and treated IFR-PP composite formed intumescent carbon layer. As can be seen in the scanning electron micrograph (SEM), outer layer carbon was intumescent and compact and formed a network structure, while the inner layer carbon was compact and continuous. So the flame retardant property can be effectively improved.