Filtern
Dokumenttyp
Sprache
- Englisch (3)
Referierte Publikation
- ja (3)
Schlagworte
- BDP (3) (entfernen)
Phosphorus-based flame retardants were incorporated into different, easily preparable matrices, such as polymeric thermoset resins and paraffin as a proposed model for polyolefins and investigated for their flame retardancy performance. The favored mode of action of each flame retardant was identified in each respective system and at each respective concentration. Thermogravimetric analysis was used in combination with infrared spectroscopy of the evolved gas to determine the pyrolysis behavior, residue formation and the release of phosphorus species. Forced flaming tests in the cone calorimeter provided insight into burning behavior and macroscopic residue effects. The results were put into relation to the phosphorus content to reveal correlations between phosphorus concentration in the gas phase and flame inhibition performance, as well as phosphorus concentration in the residue and condensed phase activity. Total heat evolved (fire load) and peak heat release rate were calculated based on changes in the effective heat of combustion and residue, and then compared with the measured values to address the modes of action of the flame retardants quantitatively. The quantification of flame inhibition, charring, and the protective layer effect measure the non-linear flame retardancy effects as functions of the phosphorus concentration. Overall, this screening approach using easily preparable polymer systems provides great insight into the effect of phosphorus in different flame retarded polymers, with regard to polymer structure, phosphorus concentration, and phosphorus species.
The pyrolysis and flame retardancy of a bisphenol A polycarbonate/silicon rubber/bisphenol A bis(diphenyl phosphate) (PC/SiR/BDP) blend were investigated and compared to those of PC/BDP and PC/SiR. The impact modifier SiR consists mainly of poly(dimethylsiloxane) (PDMS > 80 wt %). The pyrolysis of PC/SiR/BDP was studied by thermogravimetry (TG), TG–FTIR to analyze the evolved gases, and a Linkam hot stage cell within FTIR as well as 29Si NMR and 31P NMR to analyze the solid residue. The fire performance was determined by PCFC, LOI, UL 94, and a cone calorimeter under different external irradiations. The fire residues were studied by using ATR-FTIR as well as the additional binary systems PC + PDMS, PC + BDP, and BDP + PDMS, focusing on the specific chemical interactions. The decomposition pathways are revealed, focusing on the competing interaction between the components. Fire retardancy in PC/SiR/BDP is caused by both flame inhibition in the gas phase and inorganic-carbonaceous residue formation in the condensed phase. The PC/SiR/BDP does not work as well superimposing the PC/SiR and PC/BDP performances. PDMS reacts with PC and BDP, decreasing BDP's mode of action. Nevertheless, the flammability (LOI > 37%, UL 94 V-0) of PC/SiR/BDP equals the high level of PC/BDP. Indeed, SiR in PC/SiR/BDP is underlined as a promising impact modifier in flame-retarded PC/impact modifier blends as an alternative to highly flammable impact modifiers such as acrylonitrile–butadiene–styrene (ABS), taking into account that the chosen SiR leads to PC blends with a similar mechanical performance.
The pyrolysis of polycarbonate (PC) and PC/acrylonitrile-butadiene-styrene (PC/ABS) with and without arylphosphates (triphenylphosphate TPP, resorcinol-bis(diphenyl phosphate) RDP and bisphenol A bis(diphenyl phosphate) BDP) is investigated by thermal analysis as key to understanding the flame retardancy mechanisms and corresponding structure-property relationships. The correspondence between the decomposition temperature range of arylphosphates and PC is pointed out as prerequisite for the occurrence of the reaction between arylphosphate and structures that are typical for the beginning of PC decomposition. Resulting cross-linking enhances charring in the condensed phase and competes with the alternative release of phosphate in the gas phase and thus flame inhibition. Flame inhibition was identified as the main flame retardancy mechanism. The additional condensed phase mechanisms optimise the performance.