Study On Preparation And Flame Retardancy Of Halogen Free Styrene-containing Polymer Composites

Because of excellent dimensional stability, electrical insulating and processing performance, styrene-containing polymers have wide applications. However, these polymers can not resist high temperature and can burn easily, accompanied with serious melt dripping and large amount of black smoke. So it is imperative to endow them with fire retardant and smoke suppressing properties.In this paper, the physical filling method was combined with chemical modification technique to prepare a series of halogen-free flame-retardant styrene-containing polymer composites. The emphasis was laid on flame retardant property and flame retardant mechanism of the as-prepared polymer composites. The main contents of the paper are as follows:1. Such binary composites as PS/MCA, PS/PPO, PS/MH and ternary composite as PS/MCA/PPO were prepared by melt compounding, respectively. The flammability of the composites was assessed by oxygen index (OI), horizontal burning test, cone calorimetry, etc. It has been shown that the oxygen index value of the afore-mentioned composites increases with the loading of flame retardants while both heat release rate and mass loss rate of these composites decrease gradually with the rise of flame retardants. On the whole, these composites exhibit improved flame retardance and smoke suppressing performance. The PS/MCA/PPO composite displays better flame retardancy than PS/MCA and PS/PPO composites in the case of identical loading of flame retardant, revealing synergism between MCA and PPO. A series of PS/t-MH composites were prepared by annealing MH in various conditions. The experimental results indicate that the flame retardant mechanism of MH is a combination of gas phase and condensed phase flame retardation. The present study provides a solid evidence for this flame retardant mechanism.2. Cross-linked St/MH/DVB composites were prepared by in-situ polymerization with divinyl benzene (DVB) as cross-linking agent. The oxygen index of the as-prepared composites increases with the content of MH. The St/n-MH/DVB composite exhibits much improved flame retardant performance than its St/m-MH/DVB counterpart in the case of identical MH loadings. .3. The SMA molecular chains can be intercalated into the interlayer space of OMMT layers by melt compounding and form an intercalated nanocomposite. It has been shown that the SMA/OMMT nanocomposite has excellent thermal stability and fire retardancy in comparison with virgin SMA. Surface basification to SMA and the SMA/OMMT composite can increase the thermal stability and flame retardancy of these two composites noticeably. Under the same conditions, the composites treated with KOH solution exhibit better thermal and fire endurance than those with NaOH solution.