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Study of the mechanism of intumescence in fire retardant polymers. Part II: Mechanism of action in polypropylene - ammonium polyphosphate - pentaerythritol mixtures
No full textIt is shown that, by the addition of a typical intumescent mixture of ammonium polyphosphate and pentaerythritol to polypropylene, the mechanism of intumescence which develops on heating is not significantly affected by dispersion of the intumescent mixture in the polymer. On the other hand, in these mixtures, polypropylene seems to evolve, by thermal degradation, a smaller amount of flammable products than when it is heated alone. The ammonium polyphosphate-pentaerythritol additive is shown to induce fire retardant characteristics in polypropylene by means of a ‘condensed phase' mechanism
Study of the mechanism of intumescence in fire retardant polymers. Part I: Thermal degradation of ammonium polyphosphate - pentaerythrytol mixtures
No full textInteractions are shown to take place between ammonium polyphosphate and pentaerythritol in thermally degrading mixtures. Up to 500°C, gaseous products are evolved on programmed heating above 200°C in two steps with maximum rate temperatures differing by about 100-150°C. Swelling of the degrading mass seems, however, to be mainly due to gases evolved in the step occurring at the higher temperature. A strong dependence of the degradation process on the experimental conditions is observed
A study of the thermal degradation of polystyrene-chloroparaffin mixtures by thermogravimetry-high resolution gaschromatography
No full textStudy of the mechanism of intumescence in fire retardant polymers. Part IV: Evidence of ester formation in ammonium polyphosphate - pentaerythritol mixtures
No full textExperimental evidence is given of the formation of a phosphate ester as the first step in the heat-induced reaction between ammonium polyphosphate and pentaerythritol. The reaction takes place with elimination of ammonia and water and disruption of the chain structure of the polyphosphate
Study of mechanism of intumescence in fire retardant polymers. Part III: Effect of urea on the ammonium polyphosphate - pentaerythritol system
No full textUrea, which is commonly used as a ‘blowing' co-additive in intumescent coatings, is shown to depress intumescence when it is added to ammonium polyphosphate-pentaerythritol mixtures incorporated into the bulk of polypropylene. Concurrently, the fire retardant properties of the intumescent additive are depressed in the presence of urea although, in this case, a smaller amount of flammable hydrocarbons is evolved in the thermal degradation of the polymer
Study of the mechanism of intumescence in fire retardant polymers. Part V: Mechanism of formation of gaseous products in the thermal degradation of ammonium polyphosphate
No full textOn heating, ammonium polyphosphate eliminates ammonia and water in two successive steps. The first (T = 165-280°C) involves a limited weight loss (ca. 3%) and the formation of some branched structures. The transition from one crystalline form of ammonium polyphosphate to another, more stable, form, may prevent further elimination of NH3 and H2O which occurs in the second step (T > 280°C). The final product of degradation is characterised by a crosslinked POP structure formed by elimination of H2O between POH groups freed by the evolution of NH3
Thermal degradation of fire retardant chloroparaffin - metal compound mixtures. Part I: Antimony oxide
No full textThe main characteristics of the evolution of HCl and SbCl3 during the thermal degradation of chloroparaffin-Sb2O3 mixtures, which are typical fire retardant additives for polymers, have been studied. Sb2O3 reacts with HCl evolved from the chloroparaffin without any apparent effect on the dehydrochlorination process itself. Evolution of SbCl3 occurs at a maximum rate between 300 and 350°C and is somewhat delayed in the earlier stage of reaction, depending on the composition of the mixture
Thermal degradation of fire retardant chloroparaffin - metal compound mixtures. Part III: A comparison of the behaviours of antimony trioxide and bismuth compounds
No full textThe characteristics of the evolution of the flame inhibitors HCl and metal chlorides from thermally degrading mixtures of a chloroparaffin and antimony trioxide or Bi compounds are compared with reference to the behaviour of these mixtures as fire retardant additives for polymers
Combined thermogravimetry - high resolution gas chromatography for polymer degradation studies
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