The Study On The Flame Retardant Polystyrene Foam Board Using Organic Amine

With the implementation of the national energy conservation policies, expanded polystyrene (EPS) has been widely used as exterior wall materials of buildings. But it has a potential fire hazard for its flammable properties.. But the current commercially available mainly use HBCD and expanded graphite as flame retardants. Therefore, it is necessary to develop a new kind of flame-retardant EPS board with excellent flame retardant properties which is low-cost, simple and market acceptable.In this paper, different organic amines were used to modify the flame retardant property of buildings’ exterior EPS insulation board. Ammonium chloride (NH4Cl), ammonium sulfate ((NH4)2SO4), ammonium dihydrogen phosphate (NH4H2PO4) and diammonium phosphate ((NH4)2HPO4) were formulated into solutions of different concentrations, respectively.2.0wt%of carboxymethylcellulose sodium (CMC) was added into solutions as thickening agents, binder and carbon source. Then, the EPS board was fire-retardant solution soaked and flame-retardant EPS was obtained.The influence of the type and content of flame retardants on the flame retardant properties of EPS were investigated by oxygen index test and building materials flammability test. The residual carbon morphology was studied by scanning electron microscope(SEM). And the thermal properties of flame retardant EPS were studied by thermogravimetry. The degradation activation energies were calculated through Kissinger method and Flynn-Wall-Ozawa method, from which the thermal degradation kinetics was analyzed.The main results were listed as follows:(1) As thickening agent, CMC makes the content of flame retardants controllable. As binder, CMC has a good bonding effect. As a carbon source, the charring effect of CMC was obvious, and the occurrence of dripping was inhibited effectively. But CMC has also led to more stable burning and very fierce flames.(2) For the four kinds of flame-retardant EPS, the oxygen indexes were increased with the increase of the content of flame retardant agent. The increasing trend was (NH4)2SO4/CMC<NH4C1/CMC<NH4H2PO4/CMC<(NH4)2HPO4/CMC. In the building materials flammability test, with the increase of the content of flame retardant agent, the time of flame arrived150mm engraved lines was extended until it reached the engraved lines. The space frame structure of flame retardant agent distributed in the EPS and the carbon residue, significantly inhibited the contraction and dripping during the combustion of EPS. EPS reached B2flame-retardant level when the content of NH4C1/CMC, NH4H2PO4/CMC and (NH4)2HPO4/CMC was101.0phr, or the content of (NH4)2SO4/CMC was136.2phr, respectively. Then it can be used as external insulation materials of civil building, which is less than100m.(3) The flame retardant efficiency of halogen-based NH4C1/CMC was not high, and the effect of flame retardant of (NH4)2SO4/CMC was worse. NH4H2PO4/CMC and (NH4)2HPO4/CMC were with the best flame retardant effect, which means that IFR mechanism was more effective on EPS retardant modification. SEM showed that different flame retardant mechanism resulted in different carbon residue morphology. NH4C1/CMC and (NH4)2SO4/CMC mainly worked in the gas phase. The residual carbon structures of oxygen index samples were very loose. The residual carbon of flammability sample of building materials maintained a distribution structure of fire retardant after burning. NH4H2PO4/CMC and (NH4)2HPO4/CMC conformed to the IFR mechanism which mainly works in condensed phase and the oxygen index samples contained more residual carbon and with higher density after burning. The residual carbons of building materials flammability samples were clumps and filaments.(4) TG analysis showed that with the increase of heating rate, four kinds of flame-retardant EPS exhibited a thermal hysteresis phenomenon. The temperatures of5%weight loss were in advance than pure EPS and residue at600℃has increased dramatically compared to pure EPS. Flynn-Wall-Ozawa method was used to calculate the degradation activation energy of pure EPS and flame-retardant EPS, which were with a high correlation coefficient. Kissinger method for calculating the degradation activation energy of (NH4)2HPO4/CMC retardant EPS was with a poor correlation, but with a high correlation coefficient on the others. The value and change trend of degradation activation energy were different when the flame retardant and flame-retardant mechanism were not same.