The Influence Of The Carbonizing Agent Dibromoneopentyl Glycol On Intumescent Flame Retardant/Polymer Composites

The flame retardant materials are closely related to public society security, people life andproperty safety, since it is important to the research and produce of flame retardant materials.With high flame efficiency, low smoke, low toxicity, less loading and no drop,the intumescentflame retardant has become the research hot-spot. An intumescent flame retardant (IFR) wassynthesized by a water insoluble pentaerythritol phosphate melamine salt made from P2O5,PER and M, microencapsulating APP, concentrated the three essential factors of IFRS in onemolecule, overcome the shortcomings of PER, M and APP, minimizing leachingproblems.While in flame-retarded polyethylene plastic, a high loading of IFR resulted in apoor compatibility, which deteriorate the performance of the composites. Dibromoneopentylglycol (DBNPG) with low bromine content, characteristic quaternary carbon atom anddihydroxyl structure could act as the carbon source of IFR. In this project, DBNPG partlyreplacing PER was introduced into IFR，taking EVA and LDPE as matrix.The influence andflame retardant mechanism of DBNPG on flame retardant composites are explored. Theconclusions have been as following:1. DBNPG was introduced into IFR that was applied to flame retarded EVA and LDPE. TheSEM, rheological behavior, thermal analysis and property test proved that appropriateDBNPG can improved the tensile property and melting viscosity by enhanced thecompatibility of IFR/LDPE; promoted the formation of the closed char layer; decreased thecombustion heat, increased the thermostability of composites. However, excessive DBNPGwill destroy the closure of char layer by decreasing of the melting viscosity of composites andincrease the combustion. In a word, when the ratio of DBNPG/PER is around77.0/80.0, andthe ratio of IFR/LDPE is35/65, while the ratio of DBNPG/PER is38.5/90，EVA/IFR=70/30,the flame-retardant system exhibits the best flame resistancy and excellent mechanicalproperty.2. Research has explored the flame retardant mechanism of DBNPG on the flameretardancy of flame-retardant system.The dihydroxy DBNPG substituting for tetrahydroxy PER of IFR, on the one hand, can enhance the interaction between polymer and IFR; on theother hand, can decrease the melting temperature of IFR. Above two factors have the oppositeeffects on the melting viscosity of composites. Because of the high P2O5proportion of IFR0，the intumescent process is accelerated in the lower temperature,which contributes to thegreater intumescent degree of char layer,resulting from a good char layer’s thermal barrier. Inthe higher temperature,due to the poor interaction of IFR0with both EVA and LDPE,themelting viscosity of composite are low, which leads to the formation of opened andthin-walled intumescent char layer displaying poor thermal barrier property. Whenappropriate DBNPG is introduced,the melting viscosity of composite is increased,which isadvantageous to the formation of closed and compact char layer with excellent thermalbarrier property. However, excessive DBNPG lowers the melting viscosity of composite,which is harmful to the thermal barrier property of intumescent char layer with opened andthin-walled bubbles.