Preparaiton Of A Novel Triazine Charing Agent And Researches On Flame Retardancy And Thermostability Of PP/IFRs Composites

Polypropylene (PP)is one of the three most common general plastics. Owing to its simple C-Hskeletal structure and lack of flame retardant element, PP shows a limited flame retardancy. The LOIvalue of it is only18; moreover, dripping of flammable droplet and emitting of toxic smoke during thecombustion process increase the possibility of ifre. Therefore, researches on the environmentalfriendly halogen-rfee flame retardant (FR) additives of PP have become topical issues.In this paper, a novel charring agent (CA) containing triazine and diphenyl was synthesized bycyanuric chloride, diphenylamine and ethylenediamine through nucleophilic reaction. The structureand thermal stability of CA were characterized by nuclear magnetic resonance spectrometry(1H-NMR), Fourier transform infrared spectrometry (FT-IR), mass spectra (MS), element analysis(ELA), melting point test, solubility test and themogravimetric analysis (TGA). TGA results showedthat the thermstability of CA is much better than traditional charring agent pentaerythritol(PER), andthe residue of CA at700。C is26.59%.Novel intumescent flame retardant PP composites (PP/IFRs)were prepared via extrusionblending, in which IFRs are composed of ammonium polyphosphate (APP) and CA. The flammabilityand thermal degradation properties of PP/IFRs composites were characterized by limiting oxygenindex (LOI), UL94measurements, Cone calorimeter test (CCT), thermogravimetry analysis (TGA)and thermalgrametric analysis coupled with mass spectrometry (TG-MS). The results showed thatPP/IFRs composite has a LOI value as31.5with V-0of UL94ratings at20wt%additive level.The Fourier transformed infrared spectra (FTIR) and Raman spectra revealed that the flame retardantmechanism of APP/CA might be ascribed to its "aromatic" and phosphoric char formed duringcombustion. SEM observation further indicated that CA could promote forming stable and compactintumescent char layer and effectively protect the underlying polymer from burning.Moreover, three kinds of synergist attapulgite clay (ATP), titanium dioxide (TiC>2) and zinchydroxystannate (ZHS) are selected to investigate the synergistic effect in PP/IFRs systemsin thiswork. LOI, UL-94，TGA and SEM results showed that ATP used in FR intumescent systems leadsto an obvious catalytic synergetic effect on the fire-proofing performances, however, TiCh and ZHSpresented little synergism in PP/IFRs composites.