Fabrication of high transparent, mechanical strong, and flame retardant waterborne polyurethane composites by incorporating phosphorus‐silicon functionalized cellulose nanocrystals

Abstract

To manufacture transparent waterborne polyurethane composite coatings that possess desirable mechanical and flame retardancy properties is still a challenge. Herein, we first synthesized phosphorus-silicon functionalized cellulose nanocrystals (FCNC) filler, and further introduced it into waterborne polyurethane (WPU) matrix to prepare composite. The phosphorus-silicon-containing components were grafted covalently on the surface of FCNC, and the FCNC showed good dispersion level in water and WPU matrix. Moreover, the inserted FCNC could not only maintain the high transparency of WPU-FCNCs composites, but also remarkably enhancing the mechanical and flame retardancy performances. Noticeably, the WPU-FCNC3 composite containing 3 wt% of FCNC showed balanced mechanical (σ b = 16.7 MPa, ε b = 557.5%), limiting oxygen index (22.9%), and a UL-94 rating of V-2 among prepared films. Additionally, WPU-FCNC3 composite exhibited significantly reductions in heat release during combustion, and also showed a high transmittance of 92.2%. The present research supplies promising way for developing transparent, toughness, and flame retardant composite coatings.

A Review of Applications of Nanocellulose to Preserve and Protect Cultural Heritage Wood, Paintings, and Historical Papers

“…Therefore, this technique provides a hydrodynamic "apparent particle size" used to evaluate the aggregation and dispersion of NC suspensions and, to have a more accurate analysis, it is necessary to combine the results obtained with DLS with those obtained from other techniques, such as microscopy analyses [42]. Du et al, in their recent work on the functionalization of CNCs with P-and Si-for the fabrication of composite nanomaterials, used FTIR, TG-DTG, XRD, and SEM-EDS to demonstrate the successful surface modification of nanocellulose [12].…”

“…Nanocellulose has fire retardant properties and can be used as a UV shield [10]. It can also be inserted in a polymer matrix as an additive or applied on the surface of natural or synthetic textile fibers to improve their properties [11,12]. According to Omran et al, these nanomaterials are also renowned for the possibility of modifying their surfaces with various functional groups that enhance their compatibility with polymers to obtain multifunctional composite materials [13].…”

Facile Strategy to Design a Cellulose Nanocrystal-Based Nanocomposite Fire Retardant with Strong Smoke Suppression Efficiency

“…prepared a covalently modified CNC-based flame retardant (CNC@DPP@Zn) by the esterification reaction between CNC and DPP and the chelation reaction between CNC@DPP and Zn 2+ , which improved the thermal stability of the matrix and reduced the generation of smoke. Du et al synthesized phosphorus-silicon functionalized CNC (FCNC), which can decrease heat release. However, the synthesis processes of these CNC-based FRs involved a mass of organic solvents or needed harsh reaction conditions such as high temperature and pressure.…”

“…Suo et al 14 prepared a covalently modified CNC-based flame retardant (CNC@DPP@Zn) by the esterification reaction between CNC and DPP and the chelation reaction between CNC@DPP and Zn 2+ , which improved the thermal stability of the matrix and reduced the generation of smoke. Du et al 15 In this study, green IFRs composed of CNC, melamine (MEL), and phytic acid (PA) were fabricated (CNC@MEL-PA). CNC was an excellent carbon source to form a stable, protective carbon layer.…”

Robust, Flame-Retardant, and Anti-Corrosive Waterborne Polyurethane Enabled by a PN Synergistic Flame-Retardant Containing Benzimidazole and Phosphinate Groups

“…Over the years, a great deal of effort has been made on improving the flame resistance of WPUs. In general, the way to achieve flame resistance of WPUs is to add fire retardants through physical blending or introduce flame-retardant groups through chemical reactions [ 6 , 7 ]. For reactive flame-retardant modification of WPUs, the main difficulties are that how to make the introduction of flame-retardant have no obvious influence on the preparation process of dispersions, including polymerization and emulsification, nor destroy the emulsion stability and mechanical properties [ 8 ].…”