The Effect Of Modified Inorganic Particles On The Flame Retardancy Of Ethylene-Vinyl Acetate

Ethylene-vinyl acetate copolymer is widely used in many fields especially in wire and cable industry owing to its good physical and chemical properties. However, this copolymer is characterized by a high flammability which limits its application in some fields like electronic appliances where high flame retardancy is required. So it is important to improve the flammability of EVA. Currently, halogen flame retardants, intumescent flame retardants and inorganic flame retardant is often used as flame retardant to EVA. Inorganic flame retardant because of its character such as halogen-free, non-toxic and popular becomes popular. But its flame retardant efficiency is low.So it needhigh addition to have good flame retardantcy. But it will seriously affect the mechanical properties of EVA.So we need to improve the flame retardant efficiency of inorganic flame retardant. The research of this paper mainly includes the following three parts.Magnesium hydroxide (MH) was surface modified by Bis[y-(triethoxysilyl)propyl] tetrasulfide (Si-69), and its structure was characterized by Attenuated total reflectance/Fourier transform infrared spectroscopy (ATR-FTIR), thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and scanning electron microscope (SEM). The results showed that Si-69 was successfully grafted on the surface of MH. Si-69 modified MH was introduced into EVA by melt blending. The elongation at break and tensile strength of EVA increased obviously adding 5 wt% Si-69 modified MH compared with that of adding unmodified MH. This was due to Si-69 improved the compatibility between MH and EVA. After adding 40 wt% MH which modified by 5 wt% Si-69 to EVA, the limiting oxygen index increased from 21.3 to 22.3, and the peak heat release rate reduced from 601 to 489 kW/m2 compared with that of EVA containing 40 wt% unmodified MH.The second part studied the taurine intercalating modified Layered Double Hydroxide (T-LDH) impact on mechanical property and flame retardant property of EVA. Fourier transform infrared spectroscopy (FTIR) and Energy Disperse Spectroscopy (EDS) analysis showed that taurine successfully intercalated into LDH. X-ray diffraction (XRD) showed that the inter layer space of LDH enlarged from 0.77 to 0.92nm. SEM and TEM revealed the difference of NO3-LDH and T-LDH. When the adding amount was 20 wt%,the limiting oxygen index of EVA/T-LDH increased 0.9 than EVA/NO3-LDH. At the same time, the peak heat release rate and the total release reduced from 746kW/m2 and 81 MJ/m2 to 564kW/m2 and 72MJ/m2.The third part introduced a new material, that is BTP, which synthesized by benzaldehyde, taurine and hypophosphorous acid. And the structure and thermal stability are analyzed by FTIR, TGA-DTG. Then the BTP was intercalated into LDHS (BTP-LDH) by ion exchange method. The elongation at break and tensile strength of EVA/BTP-LDH improved than that of EVA/NO3-LDH. When the adding amount was 20 wt%, the limiting oxygen index of EVA/BTP-LDH increased to 22.3. And the peak heat release rate and the total release reduced to 472kW/m2 and 70MJ/m2.