Fire Retardancy Performance of Poly (Ethylene Terephthalate) Containing Melamine Cyanurate
|School||Beijing Institute of Clothing Technology|
|Keywords||PET Melamine cyanurate 2-Carboxyethyl(phenyl phosphinic) acid Flame retardancy Thermal properties|
Poly（ethylene terephthalate） （PET） resins are used in a wide range ofapplications, such as surface coatings, housings decoration, electronic components,automotive industry, and textiles due to its high dimensional stability, goodmechanical properties, good resistance to chemicals and excellent flow characteristics.However, the flammability and the poor anti-dripping property of PET limit itsapplication. Therefore, the investigation of fire retardancy and anti-drippingperformance of PET has caused great attention. Published results have showed thatthe intumescent flame retardant is high efficiency owing to the promotion ofchar-form during buring process of PET, which can inhibit the further degradation ofpolymer and improve the anti-dripping property.In this study, melamine cyanurate （MCA） and 2-carboxyethyl（phenyl phosphinic） acid （CEPPA） were selected as flame retardants, and a series ofphosphorus-containing copolyester （CP-PET）/MCA composites （CP-PET-MCA ） andPET/MCA composites （PET-MCA） were prepared by in-situ polymerization and meltblending method, respectively. The thermal stability, flame retardancy and mechanicalperformance of PET composites were investigated by using Fourier transform infraredspectrometer （FTIR）, thermal gravimetric analysis （TGA）, differential scanningcalorimeter （DSC）, limiting oxygen index instrument （LOI）, vertical burning test（UL-94）, Cone Calorimeter （CONE） and mechanical testing. The main researchcontents and conclusions are summarized as follows:1. The results of FTIR suggest the groups of carboxyl and hypophosphorous acidin 2-carboxyethyl（phenyl phosphinic） acid （CEPPA） react with ethylene glycol （EG）,and CP-PET has been successfully synthesized by polycondensation. The chemicalstructure of MCA has no variation during belnding process. SEM results show that theMCA with low content disperses uniformly in the composites. With the increase ofMCA content, some MCA particles agglomerate.2. Thermal transition temperatures and thermal stability of the composites werestudied by DSC and TGA. Compared with PET, the cold crystallization temperature(Tcc), the melting point （Tm） and the glass-transition temperature （Tg） of PET-MCAcomposties decrease slightly. The Tcc of CP-PET-MCA composites decrease and theTm and Tg of CP-PET-MCA composites have little variation. According to the TGA’sresults, the initial decomposition temperatures （Tid） of PET-MCA and CP-PET-MCAcomposites are slightly lower than that of PET in air and nitrogen atmospheres, whilethe mass of residual char of composites are higher than that of PET. It suggests thatthe compounding of CEPPA with MCA can enhance the thermal stability of PETcomposites.3. The flame retardancy of the composites was evaluated by LOI, UL-94 andCONE. The LOI value of PET-MCA composites increases from 23 to 25% and theUL-94 rating can achieve V-2 standard. The LOI value of CP-PET-MCA compositesincreases from 23 to 29% and the UL-94 rating can achieve V-0 standard. The results of CONE show that the time to ignition （TTI） of PET-MCA and CP-PET-MCAcomposites is prolonged, and the peak heat release rate （PHRR）, the total heat release（THR） and effective heat of combustion （EHC） increase.4. The flame retardant mechanism of PET-MCA and CP-PET-MCA compositeswere investigated by FTIR, SEM and energy dispersive X-ray analyzer （EDXA）.Theaddition of CEPPA compounded with MCA imparted N-P synergism effect onenhancing the fire retardancy of PET from gas and condensed phases.5. When the content of MCA in CP-PET-MCA composites is 10 wt%, thecomposites have better fire retardancy, and the mechanical properties of compositesshow slightly decrease.