A natural glue paste aminated graphene oxide onto ammonium polyphosphate towards “multiphase integrated” polymer composites: synthesis and application

Abstract

Ammonium polyphosphate (APP) is an efficient halogen-free flame retardant that has been widely applied in various polymer systems. However, its practical application is often limited by poor dispersion and insufficient interfacial compatibility. This study is inspired by the natural mechanism of mollusks secreting adhesive proteins to achieve strong adhesion to wet rock surfaces. A sustainable flame retarding-reinforcing compound was synthesized through molecular design by grafting aminated graphene oxide (NGO) onto chitosan (CS)-coated APP (APP@CS-NGO), which exhibited excellent dispersion ability, and its chemical bonding with epoxidized natural rubber (ENR) to form a “Multiphase Integrated” material (MI). The effects of interphase compatibility and dispersion of fillers on flame retardancy and mechanical properties of the materials were investigated. The results showed that the APP@CS-NGO has been successfully prepared through the NGO and APP under the effect of CS bridging. The compatibility and flame retardancy of “Multiphase Integrated” materials were further investigated. The results showed that the tensile properties of the MI 5 improved by 74.6 % compared to pure APP composites (MI 2), with a loss factor reduced to 0.83, indicating superior compatibility and dispersion in ENR. Meanwhile, the intrinsic mechanism of compatibility enhancement is explored in depth through simulation. The LOI of MI 5 increased from 19.5 % to 29.1 %, with UL-94 reaching V-0. At 800 °C, the residual carbon content rose from 26.2 % to 39.5 %, and the peak heat release rate (pHRR) was 67.8 % lower than MI 1. These results confirm that enhanced compatibility improves flame retardancy. Furthermore, this provides new ways to achieve fire-safe and sustainable polymers.