The influence of ammonium polyphosphate (APP) particle size on the performance of an intumescent formulation and on the synergistic action of a series of montmorillonite samples with different ...d‐spacings for the production of flame retardant composites was investigated. The polymer matrix employed was poly(ethylene‐co‐butyl acrylate), EBA 30, and the intumescent formulation consisted of APP and pentaerythritol (PER). After being processed, the composites were submitted to scanning electron microscopy (SEM), thermogravimetric analysis, heating microscopy, and limiting oxygen index tests. The results indicate that the greater interaction between the APP and PER molecules, caused by the increase of the contact area promoted by the reduction of the APP particle size, could favor the esterification reaction between APP423 and PER, allowing the formation of a greater amount of char precursors in shorter period of time. In addition, the montmorillonite d‐spacings had a more pronounced influence on the clays synergistic action with the intumescent formulation containing the APP with smaller particle size. Microscopy has shown to be an important tool to investigate APP particle size effect on the fire retardancy. AFM results enabled the detection of nanometric particles in the sample containing the smallest particle size of APP. SEM micrographs showed that those nanometric particles were better dispersed in the matrix, interacting more effectively with the other components, a factor probably responsible for the superior fire retardancy results. Heating microscopy revealed that the material with smaller APP particle size did show some remaining structure at the temperature of 850°C.
Ammonium polyphosphate (APP) nanoparticles enhance flame retardant properties when compared to APP microparticles by improving the char thermal stability.
Microscopy is an important tool to investigate APP particle size effect on fire retardancy.
The influence of FA ester chemical structures on the rheology and crystallization temperature of those compounds was evaluated using methyl, n‐butyl, n‐octyl, and 2‐ethyl‐1‐hexyl FA esters with ...different chain lengths and different degrees of unsaturation. The rheological properties were analyzed in a high‐precision rheometer at various temperatures, and the crystallization temperatures were determined by DSC. Esters produced from the esterification of pure FA and from the transesterification of vegetable oils (i.e., soybean, corn, linseed, and babassu coconut oils) were evaluated. The length of the FA chain was shown to have a marked influence on the viscosity and crystallization temperature of the systems, whereas branching affected only the crystallization temperature to a significant extent. The viscosity and crystallization temperature of the systems were also influenced by the degree of unsaturation. One double bond was shown to increase viscosity, whereas two or three double bonds caused a decrease in the viscosity of the systems. Unsaturation lowered the crystallization temperature in all cases, regardless of the number of double bonds. From all the oils studied, methyl esters from babassu coconut oil presented the lowest crystallization temperatures.
Pentavalent antimony derivatives, among them meglumine antimoniate, are widely used in antileishmanial therapy. The production of meglumine antimoniate involves an extremely exothermic reaction with ...antimony pentachloride, which can lead to hazardous situations. Simulation of temperature profiles of highly exothermic reactions is an efficient means of determining optimal experimental conditions that lead to reduced energy consumption and increased safety. The reaction involving SbCl5 addition to an aqueous meglumine solution was studied using an RC1 reaction calorimeter. A mathematical model was developed on the basis of energy balances. The model was used to simulate temperature profiles and to determine optimal operating conditions. The excellent correspondence between the experimental and theoretical results indicates that the mathematical model developed can adequately simulate the temperature profile of highly exothermic reactions.
The synergistic effect between spent oil-cracking catalyst (FCC catalyst) and an ammonium polyphosphate/pentaerythritol intumescent mixture was evaluated for various polyethylenic matrices. The ...mixtures were rated according to the UL-94 standard and evaluated by limiting oxygen index (LOI) testing, Thermogravimetric analysis and cone calorimetry. LOI results demonstrated a synergistic effect of the catalyst with the intumescent formulation in polyethylene, poly(ethylene-co-butyl acrylate), poly(ethylene-co-ethyl acrylate), poly(ethylene-co-methyl acrylate) and poly(ethylene-co-butyl acrylate-co-maleic anhydride). This synergistic effect also led to lower rates of heat release, total heats evolved and fume emissions, as observed by cone calorimetry. The nature of the polymeric matrix appears to influence the extent of the synergistic effect and, among the comonomers studied, butyl acrylate seems to benefit the most from catalyst addition in terms of fire-retarding properties. Apparently, the amount of comonomer affects the LOI results, although its influence as measured by other tests is not clear.
A natural Brazilian montmorillonite clay was submitted to organophilization treatments to evaluate the effect of these treatments on the flame retardancy potential of polymer composites containing an ...intumescent ammonium polyphosphate and pentaerythritol formulation. An ethylene–butyl acrylate copolymer was used as the polymer matrix. Natural or organophilic clays were added both to the pure polymer and to the polymer containing the intumescent mixture. The influence of these mineral fillers, and of their organophilization treatments, on flame retardancy was investigated by thermogravimetric analysis (TGA), limiting oxygen index (LOI), UL-94 rating standard, heating microscopy, rheological measurements and cone calorimetry. The results show that these inorganic additives have a synergistic effect on composites containing the intumescent formulation.
Waste petroleum refining catalyst from FCC unit was evaluated as a possible component in ammonium polyphosphate (APP) and pentaerythritol (PER) flame-retarding intumescent compositions for ...polyethylene-based polymers. The use of heating microscopy was introduced as a means of monitoring the intumescence process in situ. By the association of this technique with TG analysis, it was possible to observe that the addition of the waste material to the APP/PER formulations brought about an increase in the residual mass and helped the polymer samples to maintain their structure at temperatures higher than 600 °C.
Spent oil-cracking catalyst from the FCC process was incorporated into an ammonium polyphosphate and pentaerythritol intumescent mixture, both as received, and after milling and sifting. The ...influence of the catalyst's average particle size on flame retardancy performance was investigated by UL-94 rating standard, limiting oxygen index (LOI), thermogravimetric analysis (TGA) and cone calorimetry. The effect of each of the catalyst's components on the fire resistance of the final composite was also studied. The results show that the best flame-retarding properties are obtained with the finest catalyst fraction and that, of all its components, only the silica–aluminates, such as kaolin and zeolite, affect flame performance to a significant extent.
Tris(p-nitrophenyl)phosphite was prepared by a modification of a “one-pot” methodology developed for the preparation of triaryl phosphates. This exothermic reaction was performed in a Mettler RC-1 ...calorimeter. The principal aim of this work was to compare the reactivity of phosphorus trichloride and phosphorus oxychloride in their reactions with sodium p-nitrophenoxide. The reaction rate and the reaction rate constant for the synthesis of tris(p-nitrophenyl)phosphite were evaluated and compared to the obtained values for the tris(p-nitrophenyl)phosphate synthesis. Phosphorus trichloride was found to react faster than phosphorus oxychloride, but the reaction with the phosphorus oxychloride proved to be more exothermic.
Waste oil refinery catalyst from the FCC unit was tested as a possible additive for the production of polymeric composites with antimicrobial properties. The effect of the silver ion on the growth ...inhibition of bacteria (E. coli and S. aureus), mold (A. niger), and yeasts (C. tropicalis and Cr. humicolus) was studied. The catalyst was ion exchanged with silver nitrate and incorporated into thermoplastic polyurethanes with different hardness ratings. The materials produced were submitted to microbial testing both in solid and liquid media, and the effect of the polymeric matrix on the rate of silver ion release from these materials was also investigated. The results obtained show that polyurethane composite containing the silver-ion-exchanged waste catalyst successfully inhibited the growth of all microorganisms under study.
Organophilic clay particles were added to a standard intumescent formulation and, since the role of clay expansion or intercalation is still a matter of much controversy, several clays with varying ...degrees of interlayer distances were evaluated. The composites were obtained by blending the nanostructured clay and the intumescent system with a polyethylenic copolymer. The flame-retardant properties of the materials were evaluated by the limiting oxygen index (LOI), the UL-94 rating and thermogravimetric analysis (TGA). The results showed that the addition of highly expanded clays to the ammonium polyphosphate and pentaerythritol formulation does not significantly increase the flame retardancy of the mixture, when measured by the LOI and UL-94. However, when clays with smaller basal distances were added to the intumescent formulation, a synergistic effect was observed. In contrast, the simple addition of clays to the copolymer, without the intumescent formulation, did not increase the fire retardance of the materials.
PDF