The polycarbonates, intrinsically rather flame retardant, have been further flame retarded with v... more The polycarbonates, intrinsically rather flame retardant, have been further flame retarded with various bromoaromatic additives, such as tetrabromobisphenol-A polycarbonate. Other bromine additives used include brominated epoxy condensates and brominated polystyrenes. Sodium or potassium sulfonates, such as potassium perfluorobutylsulfonate, potassium diphenylsulfonesulfonate and sodium trichlorobenzenesulfonate are effective in very low loadings to meet less stringent flame retardancy. The first two allow for transparency. The blends of polycarbonate and poly(acrylonitride butadiene styrene) (ABS) are widely used for flame-retardant electrical and electronic enclosures. The major flame retardants used at present in the blends are tetraphenyl resorcinol diphosphate and tetraphenyl bisphenol-A diphosphonate (both with oligomers). Downloaded from KEY WORDS: polycarbonates, bisphenol-A, tetrabromobisphenol-A, sulfonate salts, tetraphenyl resorcinol diphosphate, tetraphenyl bisphenol-A diphosphate, diphosphates. Bayer and GE. There are now over 10 producers of polycarbonates.
The combustion performance of polyamide 6 (PA 6) and poly(butylene terephthalate) (PBT), both fir... more The combustion performance of polyamide 6 (PA 6) and poly(butylene terephthalate) (PBT), both fire retarded by phosphorus oxynitride (PON), was studied by oxygen index (OI) and Underwriters Laboratory UL94 tests. It was shown that either PON alone or in combination with different co-additives is efficient in PA 6 and much less active in PBT. Thermogravimetric experiments provided evidence that PON promotes charring in both PA 6 and PBT. The mechanism of the char formation from PA 6 and PBT in the presence of PON was discussed on the basis of IR studies of solid residues produced in the thermal decomposition. The effective fire retardant action of PON in PA 6 is related to the interaction with the polymer to produce char, whereas the less effective activity of PON in PBT is related to the unfavorable acceleration of the evolution of combustible aliphatic fragments.
An investigation has been carried out of the limiting oxygen index (LOI) test. A review of the li... more An investigation has been carried out of the limiting oxygen index (LOI) test. A review of the literature shows that, although there is abundant information on the test, it is not clear that its results correlate well with those of any other test, or indeed with those of real fires. Theoretical considerations indicate that the test could be improved by using it with bottom ignition rather than with the standard top ignition. A number of materials were tested in the cone calorimeter and in the LOI, and various correlations were attempted. In general, correlations between some of the cone calorimeter properties measured and the inverse of the LOI made sense. These correlations were not, however, sufficiently sensitive, even when investigating small effects on a single base polymer system, to justify using the LOI as a proxy for the cone in any way. The LOI is likely to continue to be used extensively. This work suggests that quality control and, possibly, mechanistic or other flame-re...
Recent patent and technical works indicate a growing interest in halogen-free solutions with the ... more Recent patent and technical works indicate a growing interest in halogen-free solutions with the predominance of the literature focusing on phosphorus-based flame retardants. Patents published on the flame retardancy of polycarbonate and its blends significantly exceed the number of patents on flame retardancy of any other polymer. Bridged aromatic diphenyl phosphates, especially resorcinol bis(diphenyl phosphate) and bisphenol A bis(diphenyl phosphate) have found broad application because of their good thermal stability, high efficiency, and low volatility.Another actively reported group of compounds are the metal salts of dialkylphosphonic acid as well as calcium hypophosphite, which have recently been found to be particularly effective in poly(butylene terephthalate) and polycarbonate. These products are synergistic with a number of phosphorus and nitrogen-containing compounds, such as melamine salts, which seem to be very efficient and commercially useful in nylons.Printed wirin...
We demonstrated that self-extinguishing polymer nanocomposites, which can pass the stringent UL 9... more We demonstrated that self-extinguishing polymer nanocomposites, which can pass the stringent UL 94 V0 standard, can be successfully prepared by combining modified organoclays with traditional flame retardant (FR) agents. Using secondary ion mass spectrometry (SIMS) and transmission electron microscopy (TEM), we determined that the addition of modified clays, which can intercalate or exfoliate in the matrix, also improved the dispersion of the FR agents. Dynamic mechanical analysis (DMA) indicated that the clays increased the modulus of the polymer above T g , which prevented dripping during burning. Cone calorimetry test showed that the nanocomposites with both FR and organoclay, had a lower peak heat release rate (PHRR) and average mass loss rate (MLR) than those with only clay or the FR agents. Extended X-ray absorption fine structure (EXAFS) data confirmed that no FR/clay interactions occurred in the solid phase, and that the synergistic effects were due to gas phase reactions. Since this mechanism is not specific, it opens the possibility of formulating self-extinguishing materials from a large class of polymers.
The polycarbonates, intrinsically rather flame retardant, have been further flame retarded with v... more The polycarbonates, intrinsically rather flame retardant, have been further flame retarded with various bromoaromatic additives, such as tetrabromobisphenol-A polycarbonate. Other bromine additives used include brominated epoxy condensates and brominated polystyrenes. Sodium or potassium sulfonates, such as potassium perfluorobutylsulfonate, potassium diphenylsulfonesulfonate and sodium trichlorobenzenesulfonate are effective in very low loadings to meet less stringent flame retardancy. The first two allow for transparency. The blends of polycarbonate and poly(acrylonitride butadiene styrene) (ABS) are widely used for flame-retardant electrical and electronic enclosures. The major flame retardants used at present in the blends are tetraphenyl resorcinol diphosphate and tetraphenyl bisphenol-A diphosphonate (both with oligomers). Downloaded from KEY WORDS: polycarbonates, bisphenol-A, tetrabromobisphenol-A, sulfonate salts, tetraphenyl resorcinol diphosphate, tetraphenyl bisphenol-A diphosphate, diphosphates. Bayer and GE. There are now over 10 producers of polycarbonates.
The combustion performance of polyamide 6 (PA 6) and poly(butylene terephthalate) (PBT), both fir... more The combustion performance of polyamide 6 (PA 6) and poly(butylene terephthalate) (PBT), both fire retarded by phosphorus oxynitride (PON), was studied by oxygen index (OI) and Underwriters Laboratory UL94 tests. It was shown that either PON alone or in combination with different co-additives is efficient in PA 6 and much less active in PBT. Thermogravimetric experiments provided evidence that PON promotes charring in both PA 6 and PBT. The mechanism of the char formation from PA 6 and PBT in the presence of PON was discussed on the basis of IR studies of solid residues produced in the thermal decomposition. The effective fire retardant action of PON in PA 6 is related to the interaction with the polymer to produce char, whereas the less effective activity of PON in PBT is related to the unfavorable acceleration of the evolution of combustible aliphatic fragments.
An investigation has been carried out of the limiting oxygen index (LOI) test. A review of the li... more An investigation has been carried out of the limiting oxygen index (LOI) test. A review of the literature shows that, although there is abundant information on the test, it is not clear that its results correlate well with those of any other test, or indeed with those of real fires. Theoretical considerations indicate that the test could be improved by using it with bottom ignition rather than with the standard top ignition. A number of materials were tested in the cone calorimeter and in the LOI, and various correlations were attempted. In general, correlations between some of the cone calorimeter properties measured and the inverse of the LOI made sense. These correlations were not, however, sufficiently sensitive, even when investigating small effects on a single base polymer system, to justify using the LOI as a proxy for the cone in any way. The LOI is likely to continue to be used extensively. This work suggests that quality control and, possibly, mechanistic or other flame-re...
Recent patent and technical works indicate a growing interest in halogen-free solutions with the ... more Recent patent and technical works indicate a growing interest in halogen-free solutions with the predominance of the literature focusing on phosphorus-based flame retardants. Patents published on the flame retardancy of polycarbonate and its blends significantly exceed the number of patents on flame retardancy of any other polymer. Bridged aromatic diphenyl phosphates, especially resorcinol bis(diphenyl phosphate) and bisphenol A bis(diphenyl phosphate) have found broad application because of their good thermal stability, high efficiency, and low volatility.Another actively reported group of compounds are the metal salts of dialkylphosphonic acid as well as calcium hypophosphite, which have recently been found to be particularly effective in poly(butylene terephthalate) and polycarbonate. These products are synergistic with a number of phosphorus and nitrogen-containing compounds, such as melamine salts, which seem to be very efficient and commercially useful in nylons.Printed wirin...
We demonstrated that self-extinguishing polymer nanocomposites, which can pass the stringent UL 9... more We demonstrated that self-extinguishing polymer nanocomposites, which can pass the stringent UL 94 V0 standard, can be successfully prepared by combining modified organoclays with traditional flame retardant (FR) agents. Using secondary ion mass spectrometry (SIMS) and transmission electron microscopy (TEM), we determined that the addition of modified clays, which can intercalate or exfoliate in the matrix, also improved the dispersion of the FR agents. Dynamic mechanical analysis (DMA) indicated that the clays increased the modulus of the polymer above T g , which prevented dripping during burning. Cone calorimetry test showed that the nanocomposites with both FR and organoclay, had a lower peak heat release rate (PHRR) and average mass loss rate (MLR) than those with only clay or the FR agents. Extended X-ray absorption fine structure (EXAFS) data confirmed that no FR/clay interactions occurred in the solid phase, and that the synergistic effects were due to gas phase reactions. Since this mechanism is not specific, it opens the possibility of formulating self-extinguishing materials from a large class of polymers.
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Papers by Edward Weil