Studies On The Preparation And Properties Of Polymer/Momtmorionite Modified With Intumescent Flame Retardant Nanocomposites

Recently，more and more environmental legislations have limited orprohibited the application of halogen-containing flame retardants onpolymer materials The study on the flame retardation wim manycharacetristies such as good performance and environmentally friendly ecthas been a significant issue Considering the specialty ofpolymer／montmorillonite(MMT)nanocomposites，three aspects for theflame retarded polymer materials were studied including intumescent flameretardant(IFR)，nano-flame retarded systems and synergism betweennano-flame retardants a11d IFRs in the dissertationA series of 5 phosphorus-nitrogen containing quaternary ammoniumsalts(PNAS)including PA A B，PAEAC，PAHAC，PDEAB and PDHAB，which composed of a carbon source，an acid source，and a gas source，weredesigned and synthesized The structures of 5 PNAS and 6 intermediateswere confirmed by FT-IR1H NMR13C NMR and high resolution massspectrometry．and all of them were new compounds PAAB．PAEAC and triethylamine. PDEAB and PDHAB were synthesized by reacting spirocyclic pentaerythritol bisphosphorate disphosphoryl chloride (SPDPC) with 2-bromo-ethylamin hydrobromide and triethylamine. The yields were 20.4-80.4%. The synthetic process parameters for a few compounds such as DPEA, CDPA and PDBA were evaluated experimentally and confirmed.MMT modified with intumescent flame retardants (IFR-MMT) was prepared by ion-exchange of Na+-montmorillonite (Na-MMT) with the PNAS. The basal spacing of IFR-MMT is 1.70-2.65 nm. It was studied that the influence of the preparation methods and technics conditions on the the basal spacing of IFR-MMT. The thermal stability and char-forming ability of the IFR-MMT are good and the initial decomposition temperature of them is between 286°C and 385°C, which can be applied to the modification of the polymer.Low density polyethylene (LDPE) matrix nanocomposites were prepared by melting intercalation blending LDPE with IFR-MMT, and polyurethane (PU)/IFR-MMT and poly methyl methacrylate (PMMA)/IFR-MMT nanocomposites were prepared by in-situ polymerization respectively. The TEM results indicated that IFR-MMT can achieve better dispersion in the polymer matrix than Na-MMT. Intercaled or exfoliated Polymer/IFR-MMT nanocomposites had been obtained by polymer melt intercalation or in-situ polymerization. It was studied that the influence of the contents of IFR-MMT in the polymer matrix, preparation methods and polymer matrix ect on the structures and forming ofnanocomposites The mechanical propegies analysis showed thatIFR—MMT had a reinforcing effect，and the s~ength and Elastic modulus ofthe nanocomposRes were increased while the elongation at break decreasedslightlyA synergistic effect between IVEVIT and intumescent flame retardantwas observed in the polymer matrix nanocomposites The thermal stabilityand char-forming ability of the nanocomposites were improved by thecarbonization action of IFR grafted onto the surface of IVEVIT and theeffective protective of MMT layers The flammability properties wereinvestigated by cone calorimeter tests The results showed that thesynergistic effect of IFR and MMT reduced significantly the flammabilityof the polymer In comparison to pure polymer，the peak heat release rates(PHRR)was reduced by 20-40％，and total heat release(THR)and averagemass loss rate(AMLR)of Polymer／IFR—MMT nanocomposites were alsoreduced obviously The time of ignition(tig。)of polymer／IFR—IVEVITnanocomposites was higher than mat of pure polymer Meanwhile．thevalues of PHRR，THR and AMLR of Polymer／IFR—MMT nanocompositeswere lower than those of Polymer／IFR or Polymer／MMT compositesThe decomposition and flame retardation mechanisms were studiedthroughout the analysis of FT-IR，scanning electronic microscopy(SEN)，transmission electron microscopy(TEM)and energy dispersive X—ray (EDX). Under Polymer/IFR-MMT nanocomposites was heated strongly and burnt, a continuous and compact intumescent charred layer was formed for the synergistic effect of IFR and MMT, which could form protective shields on the surface of the residues, thus inhibiting the transmission of heat and heat diffusion when exposed to flame or heat source. The grafting of intumescent flame retardant can enhance the dispersion uniformity of MMT in char and improve the flame retardancy of nanocomposites.