Halloysite nanotubes immobilized by chitosan/tannic acid complex as a green flame retardant for bamboo fiber/poly(lactic acid) composites

Abstract

In order to develop an environmentally benign flame retardant for bamboo/ PLA composites (BPC), chitosan (CS) and tannic acid (TA) were used as cationic and anionic polyelectrolyte respectively to stabilize halloysite nanotubes (HNT) on the surface of bamboo fiber (BF) and poly(lactic acid) (PLA). Mechanical performance tests showed that the flexural properties of BPC were moderately enhanced with the addition of HNT, while the incorporation of CS/TA complex (FR) exhibited a slight increase. The results of thermogravimetric analysis demonstrated that CS/TA complex and HNT improved the thermal stability of the BPC synergistically, which increased the char residue. Limiting oxygen index and cone calorimetry tests were used to study the flammability of BPC and the results showed that the addition of CS/TA complex and HNT had a synergistic effect on the flame retardant performance of BPC materials. The macroscopic and microscopic morphological studies confirmed the formation of HNT layer in the matrix of BPC/5FR@5HNT samples, which facilitated more stabile char residue with the best flame retardant performance. K E Y W O R D S biodegradable, biopolymers and renewable polymers, cellulose and other wood products, flame retardance, thermogravimetric analysis 1 | INTRODUCTION Bamboo is well-known as a fast-growing, widely distributed biomass resources. Bamboo fiber (BF) has excellent mechanical properties and can improve the mechanical properties of polymer composites. [1] As an extension of wood plastic composites (WPC), bamboo plastic composites are defined as a new type of general-purpose composite material composed of BF and thermoplastic materials. [2] However, most of commercially used plastics, such as polyethylene, poly(vinyl chloride), polypropylene, and polystyrene all originate from nonrenewable petroleum resources, meanwhile the plastic waste can cause serious pollution to the environment. [3] Recently, the increasing ban on use of non-degradable plastic products is enacting around the world, biodegradable polymer for composites have attracted much attention, especially BF/poly(lactic acid) (PLA)-based composite materials, since they are biodegradable, biocompatible and sustainable in nature. [4] However, BF/PLA composites (BPC) exhibit potential fire hazards in application of interior decoration, due to

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“…This could be explained by the entrapment of char residue in a polymeric structure, which retarded the diffusion of volatile degradation materials out from the sample, consequently decelerated the materials' decomposition, leaving in higher weight percentage. The result was in accordance with the study conducted by Jin et al, 59 who observed the enhancement in thermal stability and greater char formation through the simultaneous Cs and TA addition into PLA/bamboo fiber composite.…”

Tannic acid based super‐intumescent coatings for prolonged fire protection of cardboard and wood

“…2 wt% TA-MoS2/PAN [36] 2.9 332.8 N/A N/A 12.1 N/A N/A BPC/5FR@5HNT [37] 30.8 723.0 N/A N/A 136.6 N/A N/A PU-TA@RG05 [38] N/A 235.23 ± 3.78 N/A N/A 21.72 ± 0.42 N/A N/A P5/T2/S [32] 7 166 37 4.5 7.5 N/A N/A systems. However, when compared to one another, no one system completely outperforms our TA composites, with few even getting close.…”

Natural Biocidal Compounds of Plant Origin as Biodegradable Materials Modifiers

“…Chitosan/tannic acid coatings applied on biocomposites fillers increase the fire resistance of biocomposites. This kind of coatings has a potential application in materials engineering [ 275 ].…”