Preparation And Study Of Flame Retardancy Of PS/MMT Nanocomposites

Because of good transparency, dimensional stability, electrical insulating and processing performance, polystyrene (PS) has wide applications. However, PS 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 it with fire retardant and smoke suppressing properties.In this paper, the traditional method of fire retardation and the method of intercalation were combined. PS/OMMT nanocomposites and crosslinking St/OMMT nanocomposite were prepared by means of melt intercalation and in-situ polymerization, respectively. A variety of means were employed to study the microstructure and flame retardant performance of the composite materials. The main contents of the paper are as follows:1. PS/MMT composites and PS/OMMT/MH nanocomposites were prepared by means of melt intercalation method, respectively. The results of X-ray diffraction show that, the PS chains have intercalated into OMMT layers and formed intercalated structure, while the PS/Na-MMT composites can not form intercalated structure. The introduction of MH doesn't affect the formation of the intercalated structure. The flame retardancy of the composites was investigated by means of oxygen index (OI), cone calorimetry, horizontal burning methods, and so on. The results demonstrate that, with the increase of OMMT content, the OI of PS/OMMT nanocomposites gradually increase and the heat release rate (HRR), mass loss rate (MLR) and smoke production rate (SPR) gradually decrease. This clearly indicates that the composites have good flame retardancy and smoke suppression. In the case of the same MMT content, the flame retardancy of PS/OMMT nanocomposite is much better than its PS/Na-MMT counterpart. The OI of PS/OMMT/MH nanocomposites are increased remarkably and the HRR, peak HRR, MLR, SPR are all reduced to a certain degree. Comparing with PS/OMMT nanocomposites, it is implied that the introduction of MH can further enhance the flame retardancy and smoke-suppressing performance of the nanocomposites.2. Intercalated crosslinking St/OMMT nanocomposites were prepared with the method of in-situ polymerization. It is found that the OI of crosslinking PS,which were synthesized with divinyl benzene (DVB) as crosslinking agent, increase at first and then decrease with the increase of DVB content. When the content of DVB is 3 phm,the OI of crosslinking PS reaches the peak value. X-ray diffraction results show that intercalated structure was formed in the St/OMMT nanocomposites which were synthesized by means of in-situ polymerization. With the increase of OMMT content, the OI of St/OMMT nanocomposites increase at first and decrease later. The OI of St/OMMT nanocomposites reach the peak value when the content of OMMT is 6 phm. Crosslinking St/OMMT nanocomposites with different compositions were prepared with DVB and OMMT fixing at 3 phm and 6 phm, respectively. The structure and flame-retardant properties of these crosslinking St/OMMT nanocomposites were investigated. It is demonstrated that the crosslinking St/OMMT nanocomposite exhibits excellant flame-retarding and smoke-suppressing performance when the mass ratio of St:DVB:OMMT is 100:3:6.