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.
Highlights
With the rapid development of electronic industry, high dielectric constant materials with excellent performance of blocking carriers, storing electric energy and uniform electric field, stealth/wave transmission integration, etc., have been widely used in embedded capacitors, photoelectric/electro-optic devices, microwave devices and electromagnetic interference shielding [1,2]
The ionic liquids (ILs)-ammonium polyphosphate (APP), formed by the reaction of imidazolium cations of IL binding with anions of APP in the liquid toughening agent of Bismaleimide resin (BMI) in the presence of Graphene nanoplatelets (GNPs), is expected to improve the water resistance and flame retardant efficiency, and make use of a large number of micro capacitors formed between the GNPs to construct a super capacitive network, increasing the dielectric constant of BMI composites [23]
We focus on the major problem of preparing graphene nanoplatelets hybrid flame retardant GNPs/IL-APP from graphite or expanded graphite using IL assisted mechanical exfoliation and binding APP in the liquid toughening agent 4,40 - bis (2-allylphenol) (DABA) during the preparation processes of BMI composites
Summary
With the rapid development of electronic industry, high dielectric constant materials with excellent performance of blocking carriers, storing electric energy and uniform electric field, stealth/wave transmission integration, etc., have been widely used in embedded capacitors, photoelectric/electro-optic devices, microwave devices and electromagnetic interference shielding [1,2]. The IL-APP, formed by the reaction of imidazolium cations of IL binding with anions of APP in the liquid toughening agent of BMI in the presence of GNPs, is expected to improve the water resistance and flame retardant efficiency, and make use of a large number of micro capacitors formed between the GNPs to construct a super capacitive network, increasing the dielectric constant of BMI composites [23]. Based on characterization of the structure, morphology and components of GNPs/IL-APP, Materials 2021, 14, 6406 the effect of this hybrid flame retardant on the thermal stability, flame retardancy, water resistance and dielectric properties of BMI composites are studied
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