Fabrication of inorganic coatings incorporated with phosphorus-nitrogen-functionalized graphene oxide nanosheets to improve waterborne polyurethanes fire retardancy

• Published in: Polymer testing 2023-11, Vol.128, p.108219, Article 108219
• Main Authors: Xin, Hua, Chen, Yue, Li, Xinqi, Li, Yangfan, Peng, Qi, Luo, Hao
• Format: Article
• Language: English
• Subjects: Flame retardants; Graphene; N-containing flame retardants; Waterborne polyurethane
• ISSN: 0142-9418; 1873-2348
• DOI: 10.1016/j.polymertesting.2023.108219

A new inorganic flame retardant P/N-GO was prepared by chemically modifying graphene oxide (GO) with phosphorus trichloride (POCl3) and 4,4-diamino-diphenylmethane (DDM). The P/N-GO was covalently grafted into a phosphorus-containing aqueous polyurethane (PWPU) system to prepare a flame-retardant nanocomposite (P/N-GO/PWPU). Due to the uniform distribution of P/N-GO in the polymer matrix, a strong interfacial adhesion can be formed and the mechanical properties of the WPU can be significantly improved. The mechanical strength of the composites increased from 4.56 MPa to 9.16 MPa. The LOI value of WPU increased from 25.5% to 30.5%, indicating that its flame-retardant properties were improved and met the standards for flame-retardant materials. At the same time, the peak heat release rate (PHRR) was reduced from 184.374 kW/m2 to 116.730 kW/m2, which showed good flame retardant properties of P/N-GO/PWPU and was favourable for expanding the application scope and safe use of WPU. •A new flame retardant that combines flame retardancy, reinforcement, and high dispersibility.•Dual amino molecules (DDM) play the dual role of “cross-linker and flame retardant” between inorganic and polymers.•The low addition of N–P/GO still enhances the multi-phase flame retardancy of waterborne polyurethanes.