Eco-friendly flame retardant nanocrystalline cellulose prepared via silylation

Abstract

Employing proper flame retardant materials is one of the most important fire safety guidelines when constructing buildings. Most flame retardants, however, contain halogen atoms that might become harmful gases to human body during combustion. We designed and fabricated an environmentally friendly flame retardant material with a superior performance for thermal insulation. Nanocrystalline cellulose (NCC) was prepared using acid hydrolysis method, and its surface was chemically modified through silylation treatment. Various characteristics of the flame retardant material, such as morphology, chemical structure, thermal stability, and thermal conductivity were investigated. When a mass ratio of NCC to methyltrimethoxysilane was 1:5, the limiting oxygen index of the silylated NCC increased to 34% and a char yield of 80% was obtained. The silylation led to enhancement in the thermal stability of NCC and generation of the char residue. Chemical structure of the residual materials after combustion was investigated by using Fourier transform infrared spectroscopy and x-ray differential photo spectroscopy.

Effect of Cellulose Microfiber Silylation Procedures on the Properties and Antibacterial Activity of Polydimethylsiloxane

“…This indicates the increase of C-C or C-H components and the decrease of hydroxyl groups in cellulose. Besides, a new peak ranging from 282.5 to 283.5 eV (C5) indicates the formation of Si-C bonds due to the silyl groups grafting on the CF surface [61]. As shown in Figure 7d, in the high-resolution spectrum for O1s, there is one broad peak positioned at 532.2 to 533.2 eV, which could be assigned to the presence of C-OH linkages [62,63].…”

“…The first peak, ranging from 101.3 to 101.5 eV for both samples, represents Si-C bonding. The second peak, at 102.5 eV, is attributed to Si-O bonding [61]. In the case of CFvap, a larger area of Si-O means that a greater amount of silyl groups are grafted on the microfiber surface.…”

Synthesis and characterization of dialdehyde cellulose/amino‐functionalizedMCM‐41 core‐shellmicrospheres as a new eco‐friendly flame‐retardant nanocomposite

“…Therefore, alternative eco‐friendly fire retardants have been suggested to treat health and environmental concerns. Only few bio‐based materials, such as lignin and its derivatives, 18,19 cellulose, 4,6,20–23 phytic acid, 24 and nanoclay, 25 have been shown to have fire retardancy potential.…”

“…Cellulose is one of the most promising and attractive biopolymer, 20 due to its low thermal conductivity, 26 lightweight, 27 eco‐friendly feature, 28 good biocompatibility, 29 low cost, 30 and easy chemical modification, and treatment 31,32 . However, flammability is an ingrained characteristic of cellulose, that burn almost without formation of residual char.…”

“…Eco‐friendly cellulose nanofibers‐based flame retardants have been prepared by incorporating sodium bicarbonate in nanofibrils, 22 complexing cellulose nanofibrils with silica nanoparticles, 23 or modifying cellulose fibers with phytic acid 4 . Also, the flame retardancy of nanocrystalline cellulose has been improved by surface silylation 20 …”