Study On Preparation And Performance Of Flame Retardant Glass Fiber Reinforced Thermoplastic Composites

Glass fiber reinforced thermoplastic composites have excellent comprehensive properties and are widely used in daily life and industrial production.However,due to the high thermal conductivity of glass fiber,the heat transfer to the matrix is accelerated during the combustion process,and the smooth surface destroys the continuity of the condensed carbon residue,and the well-known "candle wick effect" seriously deteriorates the resistance of the composite material.In order to meet the flame retardancy requirements,more flame retardants need to be incorporated into composite materials.This topic focuses on weakening the flame retardant antagonism of glass fiber in glass fiber reinforced composite materials,focusing on interface flame retardancy,by preparing a new type of siliconcontaining flame retardant for glass fiber reinforced polylactic acid(PLA)composite materials,and using this experiment The self-made polyhydroxy flame retardant and a new type of double silane coupling agent modified glass fiber are used to modify glass fiber,and the modified glass fiber and flame retardant are compounded for glass fiber reinforced polypropylene(PP)And polyamide 6(PA6)composite materials,research the flame retardant and mechanical properties of composite materials,and explore the corresponding flame retardant mechanism.The specific work is as follows:(1)Synthesize the new flame retardant tris(hydroxymethylaminomethane)-?-aminoethyl-?-aminopropylsilanol dimethylidene phosphonate(THADP)which integrates phosphorus,nitrogen and silicon,and apply it to Glass fiber reinforced PLA system.The results showed that:adding 4 wt%THADP glass fiber to the PLA system to prepare a glass fiber reinforced PLA composite,the limiting oxygen index(LOI)reached 25.2%,and the UL-94 vertical combustion V-0 rating.It can be found from the carbon residue that the introduction of THADP promotes the adhesion between the carbon residue and the glass fiber,promotes the continuity of the carbon residue,and gives the composite material excellent flame retardant properties.(2)Modified glass fiber(FGF)is obtained by surface coating modification of glass fiber with polyhydroxy polyphosphate(APPTris(AT)),and it is combined with ammonium polyphosphate(APP)and pentaerythritol(PER)to build a barrier.Burning glass fiber reinforced PP.The results showed that the introduction of 10 wt%intumescent flame retardant(IFR)(APP:PER=3:lwt)as the bulk flame retardant,modified glass fiber reinforced polypropylene(PP/FGF/IFR)LOI reached 35.1%,passed UL-94 vertical combustion V-0 rating.The cone volume test results show that the maximum heat release rate(pHRR)of PP/FGF/IFR is 51%lower than that of pure glass fiber reinforced polypropylene composites.In addition,the introduction of FGF promotes the residual carbon residue on the surface of the glass fiber,and helps to form a dense carbon layer structure,giving the material excellent flame retardant properties.(3)Modified glass fiber(FGF)is prepared by using a new type of double silane coupling agent silicon(SPTES)to prepare modified glass fiber(FGF),and a flame-retardant glass fiber reinforced PA6 composite material is constructed with the coated red phosphorus(RP).The results show that the introduction of 5.5wt%RP as the bulk flame retardant is compared with the glass fiber reinforced PA6(PA6/GF/RP/NP)system in which SPTES is directly blended in the matrix,and the glass with modified glass fiber is used.The LOI of the fiber-reinforced PA6(FGF/RP/PA6)system has increased from 29.1%to 30.5%,and the UL-94 vertical combustion rating has been increased from V-2 to V-0;the cone volume data shows:FGF/RP/PA6 material Compared with GF/RP/PA6/RP,pHRR decreased from 410.1 kW/m2 to 355.6 kW/m2,total heat release(THR)decreased from 68.2 kW/m2 to 63.5 kW/m2,and carbon residue increased from 30.1%to 33.5%The analysis of carbon residue found that there are more dense carbon residues on the surface of the modified glass fiber,which effectively improves the adhesion between the glass fiber and the matrix carbon residue,promotes the formation of a continuous dense barrier carbon layer,and makes the composite material flame retardant.Has been significantly improved;at the same time,SPTES helps to improve the interface adhesion between the glass fiber and the matrix,showing better mechanical properties.The tensile strength of FGF/RP/PA6 is 78.4 of that of PA6/GF/RP/NP.The MPa increased to 119.2 MPa,the impact strength increased from 3.5 KJ/M-2 to 6.8 KJ/M-2,and the bending strength increased from 112.6 MPa to 137.2 MPa.