Flame retardance in some polystyrenes and poly(methyl methacrylate)s with covalently bound phosphorus-containing groups: initial screening experiments and some laser pyrolysis mechanistic studies

摘要: Abstract Styrene (ST) and methyl methacrylate (MMA) have been copolymerized with a variety of comonomers containing covalently-bound phosphorus-containing groups, including vinyl phosphonic acid, several dialkyl phosphonates, various allyl phosphine oxides. The flame retardance these polymers has preliminarily assessed through thermogravimetric analysis measurements limiting oxygen index (LOI) char yields. All the produce on burning (and also heating in air or nitrogen) LOIs higher than those parent homopolymers, indicating significant involving condensed-phase mechanisms. However, despite there being general correlations between LOI, yield phosphorus-content, some copolymers expected LOI and/or yield, whilst others lower, that phosphorus environment is important. In order to explore mechanisms more detail, laser pyrolysis/time-of-flight mass spectrometry spectrometric thermal applied study decomposition behaviour three MMA copolymers: pyrocatecholvinylphosphonate (MMA-PCVP), diethyl- p -vinylbenzylphosphonate (MMA-DE VBP) di(2-phenylethyl)vinylphosphonate (MMA-PEVP) as comonomers. pyrolysis experiments provide an insight into probable polymer behind front fire show copolymerization does not greatly change mechanism compared poly(methyl methacrylate) (PMMA). amounts monomer evolved during are much reduced for samples. Since major fuel combustion PMMA its copolymers, this effect must be contributing factor flammability shown by copolymers. MMA-DE VBP underwent most extensive following pyrolysis. particular, highly flammable methane ethene were detected. Such increased would occur if copolymer exposed high temperature conditions when burnt. Hence, seems reasonable lower value expected, it giving relatively char. Mass studies MMA-PEVP evidence PEVP unit decomposes around 200°C, eliminating styrene, evolution reaching maximum 50°C higher. Possible processes suggested.