Graphene Nanoplatelets Hybrid Flame Retardant Containing Ionic Liquid and Ammonium Polyphosphate for Modified Bismaleimide Resin: Excellent Flame Retardancy, Thermal Stability, Water Resistance and Unique Dielectric Properties

Abstract

To achieve the requirements of modified bismaleimide resin composites in electronic industry and high energy storage devices, flame retardancy, water resistance and dielectric properties must be improved. Hence, a highly efficient multifunctional graphene nanoplatelets hybrid flame retardant is prepared by ionic liquid graphite and ammonium polyphosphate. The preparation processes of the flame retardants are simple, low energy consumption and follow the green chemical concept of 100% utilization of raw materials, compared with chemical stripping. The bismaleimide resin containing 10 wt.% of the flame retardant show good flame retardancy, resulting in the limiting oxygen index increases to above 43%, and the peak heat release rate, total heat release and total smoke release decrease by 41.8%, 47.8% and 52.3%, respectively. After soaking, mass loss percentage of the modified bismaleimide resin only decreases by 0.96%, the dielectric constant of the composite increases by 39.4%, and the dielectric loss decreases with the increase of frequency. The hybrid flame retardants show multifunctional effect in the modified bismaleimide resin, due to the physical barrier, the chemical char-formation, hydrophobicity and strong conductivity attributed to co-work of Graphene nanoplatelets, ammonium polyphosphate and ionic liquid.

Methods and Mechanical Properties of Polymer Hybrid Composites and Hybrid Polymer Composites: Influence of Ionic Liquid Addition

“…Table 7 also indicates the mixing methods that are commonly employed in the fabrication of polymer hybrid composites. Mechanical and magnetic stirring are prevalent methods for thermoset hybrid composites [15,18], while melt blending and melt extrusion are generally applied in fabricating thermoplastic hybrid composites [13,20]. In natural polymer hybrid composites, there are two distinctive fabrication methods: thermomechanical kneading [1] and two-roll milling [28].…”

“…It can be seen that there is a predominance of synthetic polymers as preferred polymer matrices over natural polymers. The usage of synthetic polymers is evident through examples like bismaleimide resin [15], epoxy resin [2,8,[16][17][18][19], high-density polyethylene [20], polyamide-6 [13], poly(methyl methacrylate) [21], polyurethane [6,9,11,22,23], poly(vinyl alcohol) [24,25], and unsaturated polyester resin [26,27]. These polymers, prized for their versatility and tailored properties, seem to dominate composite fabrication.…”

“…Ammonium polyphosphate is a flame-retardant filler used to enhance the fire resistance of polymer composites. It releases non-flammable gases when exposed to high temperatures, thereby reducing the flammability of the composite [9,15,18,26,27]. Expandable graphite flakes are used to improve the thermal and flame-retardant properties of composites.…”

“…When these specific properties are needed, researchers are more likely to choose imidazolium-based ionic liquids over phosphonium-based ones. In addition, 1-butyl-3-methylimidazolium hexafluorophosphate has been used in multiple studies [9,15,[17][18][19]26,27,29], indicating its prevalence in research related to polymer hybrid composites. This ionic liquid likely contributes specific attributes such as hydrophobicity or thermal stability, suggesting its versatility and unique roles in enhancing polymer hybrid composite properties.…”

Double-Decker-Shaped Polyhedral Silsesquioxanes Reinforced Epoxy/Bismaleimide Hybrids Featuring High Thermal Stability

“…Many commercially available bismaleimide-derivatives of resin are reported due to their simple industrial synthesis and cheap raw materials [21,22]. Many studies have investigated enhancing the physical properties of BMI in order to design reactive functional groups or rigid moieties into the BMI monomers, which could also incorporate inorganic nanoparticles such as POSS, graphene, or carbon nanotubes [23][24][25][26][27][28][29]. As mentioned above, conventional epoxy resins are limited by their low thermal stability, e.g., low glass transition temperature (T g ), which means they cannot be safely be used at temperatures higher than 140 • C. On the contrary, BMI possesses high thermal stability; however, its poor processability as a solid compound is a disadvantage.…”