Preparation of piperazine cyanurate by hydrogen‐bonding self‐assembly reaction and its application in intumescent flame‐retardant polypropylene composites

Abstract

Piperazine cyanurate (PCA) is designed and synthesized via hydrogen-bonding selfassembly reactions between piperazine and cyanuric acid. Chemical structure and morphology of PCA are investigated by Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. The prepared PCA is combined with ammonium polyphosphate (APP) to prepare flame-retardant polypropylene (PP) composites. Thermostability, flammability, and combustion characteristics of PP composites are analyzed. The maximum thermal decomposition rate of flameretarded PP composites has an apparent reduction compared with that of pure PP, and obvious char is left for this intumescent flame retardant (IFR) system of APP and PCA. A high limiting oxygen index value and UL-94 V-0 rating are achieved with addition of APP and PCA. In cone calorimetry test, heat and smoke releases of PP are significantly decreased by this IFR system. Gaseous decomposition products during the thermal decomposition of flame-retardant composites are studied. Chemical structure and morphology of char residues are analyzed. The results illustrate that APP and PCA have a superb synergistic action in the aspect of improvement in fire safety of PP. A possible flame-retardant mechanism is concluded to reveal the synergism between APP and PCA. K E Y W O R D S intumescent flame retardant, mechanism, polypropylene, synergism 1 | INTRODUCTION Polymeric materials, which are now universally used in many areas, have been important to modern life for many years. Polypropylene (PP) is one of the universal polymers and has many advantages, such as easy processability, corrosion resistance, and low cost. However, it is a kind of easily combustible material, which seriously restricts its applications. Because of its emission of poisonous gases while burning, PP has high fire hazard potential for human life. 1,2 Therefore, PP materials must be modified with flame-retardant additives in order to achieve desired flame-retardant performance and meet the requirements in some application fields. Currently, considerable effort has been devoted to explore methods of reducing the inflammability of PP. Various flame retardants, such as metallic hydroxide, expandable graphite, halogencontaining flame retardants, and phosphorous-containing compounds, have been successfully developed to endow PP with flame retardancy. 3 For instance, metal hydroxides, including aluminum hydroxide and magnesium hydroxide, are used in PP, but mechanical properties of PP materials are easily destroyed by high loading of fillers. 4 As a kind of halogen flame retardants, bromine-containing compound has been regarded as the most effective flame retardant for PP. 5 However, some halogen-containing flame retardants are being phased out because of their health and environmental hazards,

Preparation of Exfoliated Organo‐Montmorillonite and Its Effect on Flame Retardancy and Mechanical Properties of Polypropylene

“…Therefore, it is of great significance to improve the fire resistance of PP to reduce fire hazards and guarantee people's life safety. [1][2][3][4] Numerous flame retardants (FR) have been developed for PP, mainly including bromine-based, [5,6] nitrogen-based, [7,8] phosphorous-based, [9,10] silicon-based, [11,12] and sulfur-based [13] as well as various compound elements. Halogen flame retardants represented by bromine-based FR have good compatibility with the PP material so that it will not significantly affect the mechanical properties of the material.…”

Preparation of Mn2+ Doped Piperazine Phosphate as a Char-Forming Agent for Improving the Fire Safety of Polypropylene/Ammonium Polyphosphate Composites

“…However, the mean yield of CO (COY) of all composites is significantly increased in comparison with the pure PP, which is attributed to the incomplete combustion of PP in the presence of APP and HP-Mn. With respect to the peak smoke production rate (PSPR) and total smoke production (TSP), the PP/APP composite gives an almost unchanged PSPR value but a higher TSP value as compared with the pure PP, which is due to the incomplete combustion of PP in the presence of APP [42]. For the PP/APP/HP-Mn composite (PP6), the lowest PSPR (0.029 m 2 /s) and TSP (7.2 m 2 ) values are achieved, with a As compared with the pure PP, the TTI (the time to ignition) values of all flame retardant composites are decreased, which should be due to the earlier decomposition of PP caused by the flame retardants.…”

Cross-Linking Modification of Ammonium Polyphosphate via Ionic Exchange and Self-Assembly for Enhancing the Fire Safety Properties of Polypropylene

“…Self-assembly technology has been applied to produce substances with specific structures by exploiting the interactions between structural units, such as hydrogen bonding and ionic interactions [ 4 , 18 , 19 , 20 ]. Recently, self-assembly technology has been adopted to prepare flame retardants due to its facile preparation method and environmentally friendly.…”