Preparation Of A New-type Environment-friendly Flame Retardant And Its Application To PET Polyester

Magnesium hydroxide(MH),being an environment-friendly flame retardant,are usually added into polymers to obtain satisfying flame retardancy in high loading,leading to poor mechanical properties of polymer composites.In this paper,organic groups were introduced into the molecular structure of MH,which can take part in the synthetic reaction of polymer and then be grafted onto long chains of polymer.It is promising that the integrated performance of flame retardancy and good mechanic properties can be achieved simultaneously because of flexible interface between MH and PET.Pure terephthalic acid(PTA)was chosen to react with MH in organic solvent to obtain an organic magnesium salt(MS)containing terminal carboxyl and hydroxyl groups.Furthermore,the terminal carboxyl can take part in the synthesis of PET so that MS can be grafted onto PET molecular chains,achieving the fundamental changes of MH from blended flame retardant to reactive one.MS was synthesized at different reaction temperatures or in different reactant ratios,whose chemical structure and thermal stability were characterized and tested.MS obtained at 140? is of complete crystal structure.The chemical structures of MSs obtained in different reactant ratios were determined by Mass Spectrum(MS)and X-ray photoelectron spectroscopy(XPS).The MS obtained in reactant ratio of 1:1 is optimum for the subsequent grafting onto PET due to the existence of terminal carboxyl and hydroxyl groups.The MS was in-situ grafted onto PET polyester to obtain flame retardant PETMS and the preparation conditions were discussed.For comparison,the MH-blended PET composite(PET/MH)was prepared.Moreover,their structural characterization as well as flame retardant and mechanical properties were tested.TGA curves of PETMS and PET/MH showed that MS and MH could enhance the thermal stability of PET and promote char formation of PET,MS showing greater enhancement.The residual weights of PETMS7 and PET/MH7 at 800? were 29.42%and 20.12%,respectively.Combustion performance and mechanical property testing of PETMS7 and PET/MH7 showed that the LOI values of PETMS7 and PET/MH7 were 25%and 23%,respectively,indicating better flame retardant effect of Ms than MH.The tensile strength,bending strength and notched impact strength for pure PET were 46.3Mpa,33Mpa and 3.74 kJ/m2.While the tensile strength of PETMS7 and PET/MH7 were 39.6Mpa and 32.2Mpa,the bending strength were 31.5Mpa and 26.3MPa,and notched impact strength were 3.52kJ/m2 and 2.78 kJ/m2,indicating better mechanical properties for PETMS than PET/MH.