Design Of Phosphorus And Nitrogen-Containing Monomers And Functionalized Silica And Investigation On Flame Retardance Of Unsaturated Polyester Resin

On the basis of research review of flame-retardant unsaturated polyester resin(UPR)and analysis of chemical structure and composition of UPR,synthetic maleic anhydride containing phosphrous and nitrogen elements was introduced into UPR molecular chain,and then crosslinked with vinyl monomers containing phosphrous elements to prepare inherent flame-retardant UPR.To further improve flame retardance of inherent flame-retardant UPR,functionalized silica hybrids containg phosphrous and nitrogen elements were synthesized and incorporated to prepare functionalized silica/inherent flame-retardant UPR composites.The influence of functionalized silica hybrids on thermal stability,thermal decomposition and combustion behavior was investigated.Combined with the analysis of gaseous and condensed phase,the flame-retardant mechanism of functionalized silica/inherent flame-retardant UPR composites was explored.The research work of my dissertation was elaborated as follows:1.By the molecular design method,vinyl monomers(ADPI and ADPA)containing phosphrous elements were synthesized via the reaction of chlorodiphenylphosphine and diphenyl chlorophosphate were reacted with 2-hydroxyethyl acrylate to synthesize vinyl monomers containing phosphrous elements(ADPI and ADPA),respectively.Then ADPI and ADPA were crosslinked with unsaturated polyester oligomer to prepare flame-retardant UPR containing phosphrous elements.DSC non-isothermal curves were utilized to investigate the influence of vinyl monomers on curing behavior and obtain crucial data such as activation energy,optimal curing temperature and so on.The initial decomposition temperature and maximum mass loss rate of phosphatized unsaturated polyester resin was decreased,but the charring amount was increased.Vinyl monomers containing phosphrous elements can decrease the release rate of heat and smoke.Pyrolytic volatiles such as hydrocarbons,aromatic compounds,CO were significantly decreased and the generated PO· free radicals can caputre active H· and OH· in the flame.Raman spectra and SEM images demonstate that the compactness and graphitic degree of char residues are increased,enhancing the barrier effect.In conclusion,ADPA has better flame-retardant efficiency than ADPI.2.Flame-retardant maleic anhydride(FRC-6 and DOPO-MA)was synthesized via the esterication reaction of maleic anhydride and diethyl bis-(2-hydroxyethyl)amino methyl phosphinate(FRC-6),and addition reaction of maleic anhydride and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO),respectively.Then FRC-6 and DOPO-MA were reacted with propanediol and phthalic anhydride to obtain UPR oligomers containing phosphrous and nitrogen elements.The UPR oligomers were crosslinked with ADPA to prepare inherent flame-retardant UPR-DOPO and UPR-FRC.The thermal decomposition and curing behavior were investigated by thermogravimetric analysis and DSC non-iso thermal curves,respectively.Peak heat release rate(PHRR)and total heat release(THR)were significantly decreased.Pyrolytic volatiles such as hydrocarbons,aromatic compounds,CO were significantly decreased and the generated PO· free radicals can caputre active H-and OH-in the flame.The swelling degree,compactness and graphitic degree of char residues are increased to enhance barrier effect,inhibiting the release of heat and toxic smoke.3.Hollow silica spheres were synthesized by hard-templating method using sodium silicate as silica precursor and polystyrene spheres as interior templates,and then reacted with APTES to prepare aminated hollow silica.In addition,cyanuric chloride and hexachlorocyclotriphosphazene were reacted with p-hydroxy-benzaldehyde to synthesize TFT and HAPCP,respectively.TFT and HAPCP molecules were grafted onto aminated hollow silica,and reacted with Dimethyl phosphite and DOPO to prepare SiO2-TFTP and SiO2-HAPCPD hybrids.The addition of SiO2-TFTP and SiO2-HAPCPD hybrids results in the decrease of PHRR and THR of UPR-FRC composites.Pyrolytic volatiles such as hydrocarbons,aromatic compounds,CO were significantly decreased.The charring amount,compactness and graphitic degree of char residues are increased to enhance barrier effect.2.0wt%SiO2-HAPCPD/UPR-2 composites have the best flame-retardant performance.4.Mesoporous silica was obtained by the sol-gel method and melamine cyanurate was wrapped onto mesoporous silica.The addition of SiO2@MCA-2 hybrids results in the decrease of the maximum mass loss rate during thermal decomposition.PHRR and THR of SiO2@MCA-2/UPR were decreased to 343.2 kW/m2 and 33.7 MJ/m2,respectively.Pyrolytic volatiles such as hydrocarbons,aromatic compounds,CO were significantly decreased.The charring amount,compactness,swelling degree,thermal stability and graphitic degree of char residues are increased to enhance barrier effect.5.Aminated mesoporous silica was synthesized by the co-precipitation method using tetraethoxysilane and APTMS with the aid of cetyltrimethylammonium chloride,and then was reacted with formaldehyde,phosphorous acid and piperazine in aqueous phase.The modified mesoporous silica was added to prepare inherent flame-retardant UPR composites under ultrasonication.Thermal and smoke hazards of SiO2-PN3/UPR composites were greatly decreased.Fire growth index(FGI)of SiO2-PN3/UPR composites was only 3.7 kW/(m2·s).Pyrolytic volatiles such as hydrocarbons,aromatic compounds,CO were significantly decreased.Moreover,the addition of SiO2-PN3 hybrids results in the increase of charring amount,compactness,swelling degree,thermal stability and graphitic degree of char residues.