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

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          Abstract

          Several studies show a synergistic effect between intumescent formulations and aluminosilicates, such as zeolites and clays, but little is known about the effect of acidity of these additives on the synergistic action. In this work, H-ZSM-5 zeolite was submitted to desilication treatments for 30 min and for 2 h, and silicalite-1 was synthesized. The objective was to obtain samples of equivalent crystalline structure, but with different amounts of acid sites, in order to evaluate the effect of acid concentration of H-ZSM-5 zeolites on the synergistic action with an intumescent formulation composed by ammonium polyphosphate and pentaerythritol in polypropylene. H-ZSM-5 zeolites and silicalite were characterized by X-ray diffraction, nitrogen adsorption analysis and temperature-programmed desorption of ammonia. The desilication produced H-ZSM-5 zeolites with similar volumes of mesopores in both treatments, but the zeolite resulting from 2 h of desilication presented a higher concentration of acid sites than the zeolite from 30 min. The flame-retardant properties were evaluated by UL-94 classification, limiting oxygen index, glow-wire, thermogravimetric analysis and heating microscopy. The results showed that increasing the concentration and accessibility of the acid sites of H-ZSM-5 zeolites the flame-retardant properties of the studied composites improved. It is suggested that the increase of acid site concentration positively influences the catalysis of the reaction between ammonium polyphosphate and pentaerythritol, favoring the production of the precursors of the intumescent layer.

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          Most cited references 45

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          Recent Advances for Intumescent Polymers

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            Fire retardant polymers: recent developments and opportunities

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              Synergistic effect of zeolite in an intumescence process: study of the carbonaceous structures using solid-state NMR

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                Author and article information

                Journal
                Polymers (Basel)
                Polymers (Basel)
                polymers
                Polymers
                MDPI
                2073-4360
                16 December 2019
                December 2019
                : 11
                : 12
                Affiliations
                Universidade Federal do Rio de Janeiro, Instituto de Química, Cidade Universitária, CT, Bloco A, Rio de Janeiro 21941-909, Brazil; felipereis314@ 123456gmail.com (F.R.B.); mjcrezende@ 123456gmail.com (M.J.C.R.); vicerodrigues@ 123456gmail.com (V.d.O.R.); rsandra@ 123456iq.ufrj.br (R.S.V.N.)
                Author notes
                Article
                polymers-11-02110
                10.3390/polym11122110
                6960519
                31888118
                © 2019 by the authors.

                Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ( http://creativecommons.org/licenses/by/4.0/).

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