Preparation And Properties Of Halogen-free Intrinsic Flame Retardant Polyester Based On Magnesium Hydroxide Composites

Polyester polymer materials are widely used in various corner of national life due to its excellent physical properties,easy processing,corrosion resistance.Such as in the fields of textiles,electronic appliances,building materials.The traditional polyester materials have symmetrical chemical structure,low limiting oxygen index(LOI)and so on,which limited its extensive application in many fields.Most of polymer materials are easy to burning,and not easy to extinguishing.Nevertheless,often produces molten drops and harmful substances during burning,which seriously threaten human life and property safety.Therefore,study a highly efficient and environmentally friendly flame retardant polymer material is the focus of current research.However,flame retardant is the key to make the material achieve flame retardance.The inorganic flame retardant magnesium hydroxide(MH)is not only non-toxic,but also low cost and good thermal stability,it can reduce the temperature of polymer surface to achieve flame retardant and smoke suppression effects.Conventional MH flame retardants have high amounts in the polymer matrix and poor in compatibility with the matrix.In order to improve the dispersion of MH in the matrix,in this paper,a series of flame retardant polyester composites were prepared by grafting functionalized magnesium hydroxide onto the polyester chain.The main research contents were summarized as follows:I: Magnesium hydroxide(MH)by neutralizing with carboxylic acid compounds maleic anhydride(MA)to prepare an organic magnesium hydroxide(OMH)flame retardant,which can participate in the synthesis of halogen-free?low-smoke flameretardant unsaturated polyester resin composite(FR-UPR).The structure and surface morphology of OMH and FR-UPR by characterization.The experimental data showed that LOI value increased from 20.5% to 26.4% of FR-UPR composites containing OMH1% and EPG6%;Peak heat release rate(PHRR)and total heat release(THR)were reduced by 67.3% and 31.6%,respectively.The SEM test of the residual carbon after combustion shows that a honeycomb-like structure which can effectively insulate and oxygen.II: In this work,a functional organic magnesium salt(OFMS)was designed and synthesized.OFMS was introduced as comonomer into the PET polymer chain to prepare intrinsic flame retardant polyester composite PET/OFMS.The structure of OFMS was characterized.It was found that the hydroxyl groups at both ends of MH reacted completely,and OFMS have complete crystal structure.The mechanical properties and flame retardancy of the composite were investigated.The results indicated that the LOI of PET/OFMS4% and PET/MH4% materials reached 28% and25%,respectively;The flexural strength of PET/OFMS4 and PET/MH were 60 MPa and 40 MPa respectively,indicating that OFMS has positive effect on the improvement of mechanical properties and flame retardant properties of materials.The carbon layer with a tight continuous surface after combustion could act as a physical barrier,significantly reducing the heat release rate,total heat release,carbon monoxide and carbon dioxide yield.Thus effectively preventing further degradation of the material at high temperatures.III: A novel phosphorus-magnesium flame retardant(PMFR)was synthesized by the reaction 9,10-dihydro-9-oxa-10-phosphoryl phenanthrene-succinic acid(DDP)with MH.PMFR was used to prepare a series of different flame retardant contents of polyester composites(PET/PMFR)by in-situ polymerization with the terephthalic acid(TPA)and ethylene glycol(EG).TGA showed the residual carbon contents of the(PET/PMFR)composite had a significant increase at 700 °C,when different amounts of PMFR were introduced;The elongation at break,flexural modulus and flexural strength of(PET/PMFR2.5%)had greater improvement compared with pure PET material,which were increased by 96.2%,6.5%,6.6%,respectively;LOI from 24%increased to 29%.In addition,through vertical burning test(UL-94)test showed that the flame retardancy and anti-melting drip performance of PMFR were significantly better than MH and DDP.