The Research Of The Flame Retardant Expandable Polystyrene

Expandable polystyrene is widely used because of its perfect property. Through designing several times of polymerization of styrene, we have studied the influence of the dispersant's amount and proportion on the PS particle and particle distribution, the influence of initiator's kinds and amount on the PS molecular weight and molecular weight distribution, and the influence of polymerization temperature,stirring speed,the ratio of water to oil and impurities on the polymerization, represent the molecular weight and molecular weight distribution of polymer. The results showed that:when the ratio of the amount of compound dispersant agent to the styrene is 0.24%, TCP:HEC=1:1, BPO/St=0.8%, H2O/St=2～3(by weight), stirring speed is 350r/min, and the temperature of polymerization is 90±℃, the rising process is in stages, then the particle size of PS we got is moderate, particle size distribution is centralized, the content between 6-26 mesh is 95.68%, while 8-20 mesh is 85%, and transparency of the particle is good, the rate of production can reach 98.96%.In this paper, besides using the traditional free radical initiator-benzoyl peroxide to initiate the polymerization, we also use another tow kinds of difunctional initiator-1,1-bis (tert-buty peroxy) cyclohexane and 2,2-Di(tert-butylperoxy)butane to initiate the polymerization of styrene. Through comparison, we investigate the influence of difunctional initiator on the polymerization, especially on the polymer molecular weight. The results showed that:the molecular weight of polystyrene can be increased obviously by using the difunctional initiator, the number-average molecular weight can reach 63.2×104, this can provide a good foundation to prepare excellent mechanics property EPS and extend the application area.In this paper, we have also prepared PS particles with foaming agent, the flame retardant was added to the reaction system between the polymerization, then the flame retardant expandable polystyrene was produced by dipping,prefoaming,aging and molding processing. By designing contrasting experiments with different kinds and amount of flame retardant, we have studied its influence discipline on the flame retardant property of EPS. The result showed that:when the percentage of HBCD surpass 4.3% by the monomer, the flame retardant of EPS is good, and the self-extinguish time is in 2 seconds; when the ratio of HBCD to Sb2O3 is between 3:1-4:1, the self-extinguish time of EPS is less than 2 seconds, especially when HBCD/Sb2O3=3.5:1, the flame retardant property is perfect; when the amount of HBCD and Sb2O3 is invariable, the self-extinguish time of EPS is declined obviously while the amount of Al(OH)3/Mg(OH)2/P increasing, the material is hard to burn when the percentage of inorganic flame retardant surpass 3.0%.We also have presented the structure of the polymer and made the thermal analysis, and tested the bending property,compressing property and other properties of EPS. Through the investigation we have learned that the bending and compressing properties of EPS with high foaming rate is worse than the EPS with low foaming rate.