Flame Retardancy and Mechanism of Novel Phosphorus-Silicon Flame Retardant Based on Polysilsesquioxane

Abstract

A novel phosphorus-silicon flame retardant (P5PSQ) was prepared by bonding phosphate to silicon-based polysilsesquioxane (PSQ) and used as flame retardant of poly (lactic acid) (PLA). The results show that PLA with 10 wt % P5PSQ has a limiting oxygen index (LOI) 24.1%, the peak heat release rate (PHRR) and total heat release (THR) of PLA decrease 21.8% and 25.2% compared to neat PLA in cone calorimetric test, indicating that P5PSQ shows better flame retardancy in comparison to PSQ. Furthermore, the study for the morphology and composition of carbon residue after the combustion of PLA and the gas release of PLA during combustion illustrate that P5PSQ has flame retardancy in condensed phase and gas phase simultaneously. In condensed phase, phosphorus from phosphate promotes the formation of more stable and better carbon layer containing Si and P, which inhibits the transfer of heat and oxygen in the combustion. In gas phase, the phosphate in P5PSQ emits phosphorus-containing compound that can restrain the release of C–O containing products, which may have effective flame retardancy for PLA in gas phase to a certain extent. In one word, P5PSQ is denoted as a good phosphorus-silicon synergistic flame-retardant.

PP/POE thermoplastic elastomer prepared by dynamic vulcanization and its flame retardant modification

“…20 The siloxane in the silicone powder will migrate to the combustion interface to form Si-C and Si-O bonds during combustion, thereby enhancing the thermal stability of the carbon layer, meanwhile, the layered SiO 2 decomposed by siloxane can also effectively prevent the oxidation of carbon layer. 21 As the number of silicon-based flame retardants in the compound flame retardant system increases, the T-5% and carbon residue rate of TPE both increase, while D max shows a downward trend. This shows that the appropriate amount of silicone powder can effectively improve the stability of the carbon layer of the bromine-phosphorus flame retardant, but increasing the amount of GM will gradually weaken the flame retardant enhancement effect.…”

Recent Developments in the Flame-Retardant System of Epoxy Resin

“…Phosphorus-containing flame retardants have a significant synergistic flame retardant effect while combined with silicon compounds, and silicon can improve the thermal stability of carbon layer catalyzed by phosphorus [88,89]. In recent years, the phosphorus-silicon synergistic flame-retardant system have been intensively investigated by many researchers [90,91].…”

Clays as Inhibitors of Polyurethane Foams’ Flammability

“…In the solid phase, phosphorus-containing polymers undergo thermal decomposition with the release of phosphoric and polyphosphoric acids. The acids lead to the dehydrogenation of the polymer, resulting in the formation of a highly viscous liquid film on the surface of the combusted material, which limits the transport of mass and heat between the gas and condensed phases [88]. Organophosphorus compounds occupy a unique position among phosphorus flame retardants, which include, among others: organic phosphates (V); phosphates (III); diphosphates (V); pyrophosphates; and phosphorus halides.…”