A Branched Polyelectrolyte Complex Enables Efficient Flame Retardant and Excellent Robustness for Wood/Polymer Composites

Abstract

Wood/thermoplastic composites (WPCs) have been restricted in some fields of building construction and electrical equipment because of their inherent high flammability and lower toughness. In this work, a branched crosslinking network polyelectrolyte complex (PEC) has been designed by incorporation of polyethyleneimine (PEI), a cation polyelectrolyte end capped amine groups, into cellulose nanocrystals (CNC), and ammonium polyphosphate (APP) via self-assembling. The hydrogen bonding interactions, penetration, and mechanical interlock provided by PEC effectively enhance the interfacial bonding within matrix, wood fibers, and flame retardant. Interestingly, it generates abundant micropores on the inner structure of WPC. The excellent interfacial bonding performance and easy-to-move molecular chain successfully transfer the stress and induce energy dissipation, simultaneously giving rise to higher strength and toughness for WPC. As well as the PEC endows WPC with a promotion in both smoke suppression and UL-94 V-0 rate. Additionally, the peak heat release rate and total smoke release for WPC obviously reduce by 36.9% and 50.0% respectively in presence of 25% PEC. A simple, eco-friendly, and concise strategy exhibits prospects for fiber-reinforced polymer composites with effective flame retardancy and mechanical robust properties.

Three-Dimensional Cross-Linking Network Coating for the Flame Retardant of Bio-Based Polyamide 56 Fabric by Weak Bonds

“…It can be used as a blowing agent and carbon source in ammonia-based flame retardants [ 28 ]. The large number of amino groups gives PEI a strong adsorption capacity [ 29 , 30 , 31 ], which can fix the flame retardant on the fabric surface through a large number of hydrogen bonds [ 32 ], and also enhances the flame retardant’s properties by promoting the absorption of carbon dioxide and moisture in the air [ 33 , 34 ], as well as facilitating the introduction of other flame-retardant components through chemical linkage or hydrogen bonding [ 35 , 36 ]. The hyperbranched structure of PEI enables the connection with other molecules to form the cross-linking network and enhance the flame retardant’s performance [ 37 ].…”

Fire Behavior of Wood-Based Composite Materials

“…WPC with various manufacturing processes and their effective flame retardants[145,[166][167][168][169][170]. WF composite without fire retardant recorded 28.7% mm/min UL-94 completely burnt the sample with low LOI value of 18%.…”