Microscopy as a tool to investigate the influence of ammonium polyphosphate particle size on the flame retardant properties of polymer composites

Abstract

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.

Structure and properties of flame‐retardant Lyocell fibers prepared by blending method

“…Small particle sizes afford good flame retardancy effect and have little influence on spinning; however, the use of small particles greatly increases the production cost. [30,31] Figure 1 shows the morphology and particle size distribution of MPP and MCA. Both flame retardants have irregularly shaped particles with a particle size ranging between 0.2 and 2 μm.…”

Synthesis and Application of H-ZSM-5 Zeolites with Different Levels of Acidity as Synergistic Agents in Flame Retardant Polymeric Materials

“…The behavior of the material under heating and the preservation of the intumescent layer structure were observed by the technique [41]. The analyses were carried out in a Leitz (Oberkochen, Germany) heating microscope (model 1A) and the images were captured by a Samsung SDC 414 ND camera.…”

Experimental investigation of the flame retardant and form-stable composite phase change materials for a power battery thermal management system

“…Related studies have investigated the influence of APP/RP flame retardants on flammability. These studies indicated that the combination of APP and RP had a significant synergistic effect that would promote carbon-forming capacity and a dense carbon layer to produce sufficient insulation, further reducing the combustion rate and heat release [29][30][31][32][33]. Yasemin et al [34] investigated the fire performance of LDPE-based composites containing APP and RP.…”