Study On The Preparation And Properties Of Intrinsic Flame Retardant Unsaturated Polyester Composites

Unsaturated polyester resin,with excellent comprehensive performance,comparatively low price and easy processing,plays a great role in polymer materials.However,conventional UPR is highly flammable,which limits the application in many areas.To solve the issues above,the flame retardant modification of UPR should be necessary.In addition,halogen-containing compounds produce a large amount of toxic gases during combustion,which results in serious harm to the environment.Therefore,the halogen-free flame retardant will become the future research trends of the flame-retarded field in both academia and industry.Meanwhile,the phosphorus flame retardant attracts much attention due to the high fire-resistance efficiency and environmental protection.And two preparation methods for flame retardant polymer material can be used,the one is additive-type flame-retarded modification that is to blend the non-reactive additives and UPR matrixes;the other is intrinsic flame-retarded modification—to introduce reactive flame retardant monomers into UP chain or pre-polymer and they undergo cross-link copolymerization under appropriate conditions.Aiming at overcoming the drawbacks of UPR,several halogen-free phosphorus containing monomers were synthesized and then incorporated into UP chain via chemical reaction.In addition,different intrinsic flame retardant unsaturated polyester composites were prepared.Study the effect of the phosphorus-containing monomers on thermal stabilities,combustion behaviors of UPR matrix,revealing the flame retardant mechanism.The detailed outline are listed as follows1.A flame retardant phosphine oxide monomer(TAOPO)with P-C bond was synthesized,and then copolymerized with unsaturated bonds of UP in different ratios to obtain a flame-retardant unsaturated polyester resin.The thermal property,combustion behavior and flame retardant performance was characterized by TGA,LOI and cone calorimetry test,indicating that TAOPO can strengthen the thermal stability of UPR matrix and produce additional carbonaceous residue in higher temperature region.Peak heat release rate(PHRR)and total heat release(THR)value of UPR-3 from cone calorimetry experiments reduced significantly,corresponding to the increase of LOI value.The flame retardant mechanism was investigated by TG-FTIR and RT-IR spectroscopy,indicating that the phosphine oxide oligomer in flame retardant UPR can decline the release of volatile gas during pyrolysis and transformed into more thermally stable polyphosphates species at higher temperature,giving rise to highly structured char residue which prevented the further degradation of the underlying polymer matrix,fully according with SEM results.2.A phosphorus containing monomer(DPHE),synthesized by the reaction of phosphorus oxychloride,neopentyl glycol and hydro xyethyl acrylate,was incorporated into UPR by radical bulk polymerization as a reactive flame retardant.And the thermal stability,degradation behavior and flame retardancy was investigated.And the morphology of the char layer of UPRs was investigated by scanning electron microscopy(SEM).And the flame-retard ant mechanism has been inferred.3.A reactive phosphorus-containing monomer(DPHE),synthesized by the reaction of phosphorus oxychloride,phenol and hydroxyethyl acrylate,was incorporated into unsaturated polyester by radical bulk polymerization as a reactive flame retardant together with multiwalled carbon nanotubes(MWCNTs).And samples with different components were obtained.The combustion property of unsaturated polyester composites was investigated.And cone calorimetry test was employed to evaluate the heat release during combustion,suggesting that PHRR and THR of modified materials dropped markedly.Moreover,the thermal degradation behaviors and the morphology of char residue of materials were identified by thermogravimetric analysis(TGA)and SEM,respectively.And the flame-retardant mechanism has been inferred.