Effect Of Charring Polymers On The Retardancy Of Hips-montmorillonite Composites

Polymer / layered silicate (PLS) nanocomposites are a new type of flame retardant materials. Compared to many traditional fire-retardant materials, the new materials present a lot of excellent properties, such as the low content and good effective; the small deterioration to other properties of polymer matrix. Moreover, it can improve the mechanical properties, thermal stability and dimensional stability for some resins, and release less smoke and toxic gases, which is a good environmentally friendly fire-retardant material.But now there is still shortcomings for the flame retardant of PLS nanocomposite, which presents the different effect in a variety of different evaluation and the flame retardancy should be improved further. In this work, high impact polystyrene polymer (HIPS) and modified montmorillonite (OMMT) by cetyltrimethylammonium bromide (CTAB) was used, and the according HIPS / OMMT nanocomposites were prepared by melt intercalation. Some high charring polymers including polycarbonate (PC), polyetherimide (PEI), polyphenylene oxide (PPO), polyphenylene sulfide (PPS) and phenolic resin (PF) were selected and their influence was researched for HIPS / OMMT nanocomposites.The selected charring polymers were compounded with HIPS/OMMT composites and the new flame retardant system was obtained, which was evaluated by cone calorimeter, limit oxygen index (LOI) and the horizontal and vertical burning test (UL 94). Cone calorimeter test results show that the addition of charring polymer can reduce the heat release rate and mass loss rate for HIPS/OMMT composites, and the flame retardant property was improved further. The residue remains increase for the addition of charring polymer. The LOI and UL 94 test results showed that the flame retardancy of HIPS/OMMT composites was little effect by the addition of charring polymer. LOI increased slightly, but not obviously, some of the complex system of horizontal burning level declined slightly.Red phosphorus flame retardant (RP) and polymers of charring was used for further optimizing of HIPS/OMMT composites. Cone calorimeter experiments showed that the heat release rate and mass loss rate decreased significantly. But the findings showed that the flame retardant properties of composites increase mainly from the role of red phosphorus, while the polymers of charring for flame retardant improvement has not been reflected. Similarly, the LOI increases for the flame retardant system, which mainly affected by the addition of RP but litter influence from the polymers of charring.Horizontal and vertical burning test results showed that a large amount of red phosphorus was needed to retain the levels of flame retardant for the HIPS/OMMT composites system by adding red phosphorus alone. The addition of some charring polymers can increase the level of vertical combustion greatly. Moderate amount of red phosphorus, in a small amount of charring polymer conditions, the level FH-1 of horizontal and the level FV-0 of vertical burning can be obtained respectively for HIPS/OMMT composites, which showed good flame retardant properties.