Lignocellulose-Chitosan-Multiwalled Carbon Nanotube Composites with Improved Mechanical Strength, Dimensional Stability and Fire Retardancy

Abstract

A novel composite composed of lignocellulose (LC), glutaraldehyde crosslinked chitosan (GC) and multiwalled carbon nanotube (MWCNT) was fabricated by the hot-pressing process. The effect of the additional GC and MWCNT on the mechanical strength, dimensional stability and fire retardancy of lignocellulose composites was investigated. The results showed that LC/GC/MWCNT composite exhibited the maximum modulus of rupture (MOR) of 35.3 MPa, modulus of elasticity (MOE) of 2789.1 MPa and internal bonding (IB) strength of 1.2 MPa. Meanwhile, the LC/GC/MWCNT composite displayed improved dimensional stability with a thickness swelling (TS) value of 22.4%. Besides, the LC/GC/MWCNT composite exhibited improved fire retardancy with a limiting oxygen index of 29.0%. The peak heat release rate, the total heat release, the total smoke production and the maximum smoke production ratio of LC/GC/MWCNT composite decreased by 15.9%, 10.7%, 45.5% and 20.7% compared with those of LC composite, respectively. Therefore, the LC/GC/MWCNT composite may be a promising candidate for green wood based composites.

Advancements in traditional and nanosized flame retardants for polymers—A review

“…18 1.6.5.1 Carbon nanotube A wide range of studies have shown that carbon nanotubes (CNTs) either single-walled (SWCNTs) or multiwalled (MWCNTs) are among the most promising alternatives for traditional flame retardants to be used in different polymers, such as, PP, PE, PLA, lignocellulose, epoxy resin. [84][85][86][87][88] These studies have demonstrated that adding a small amount of well-dispersed CNTs (<5 wt%) to polymer composites can significantly improve the fire behavior due to their fascinating chemical and physical properties. 89 CNTs have a highly elongated structure with a large aspect ratio.…”

“…85,90 Moreover, low flame spread rate, smoke-suppression, and anti-dripping properties have been reported while incorporating CNTs in different polymers. 86,87 Improvement in fire retardancy of polymer composites is strongly dependent on uniform dispersion of CNTs and their interactions with the polymer matrix. 84,89 There are different surface modification methods and fabrication techniques, supporting CNTs homogenous distribution in polymers.…”

“…91 Chemical treatment of CNTs with concentrated sulfuric acid and nitric acid has proven to be successful when incorporated in different polymers, such as, polylactic acid or lignocellulose. 86,89 It was found that the incorporation of 2 wt% of acid-treated MWCNTs to lignocellulose/chitosan composites (LC/GC/MWCNT) can decrease the total heat release and the total smoke production by 10.7% and 45.5% compared with those of virgin polymer during cone calorimetry test. LC/GC/MWCNT composite also exhibited higher LOI values compared to neat polymers ( Figure 5).…”

Fabrication of Superhydrophobic Mg/Al Layered Double Hydroxide (LDH) Coatings on Medium Density Fiberboards (MDFs) with Flame Retardancy

“…Medium density fiberboards were prepared according to our previous studies [ 5 ]. In a typical process, a mixture of 2% ( w / v ) was obtained by dissolving chitosan in an acetic acid solution of 1.5% ( w / v ) at room temperature for 2 h under stirring.…”

“…This is due to their abundance, low cost, and easy machinability [ 1 , 2 ]. In general, the fiberboards exhibit hydrophilic, hygroscopic, and flammable properties during application due to the existence of abundant hydroxyl groups in the wood fiber surface, their porous structure, and organic nature [ 3 , 4 , 5 ]. This sensitivity to humidity changes and flame usually results in a decrease in the service life of fiberboards and a threat to the human safety.…”