Using colloidal lignin intercalated montmorillonite nanosheets as synergistic and reinforced agent for flame‐retardant poly(butylene succinate) composites

Lignin/montmorillonite (LM) nanocomposites were fabricated via intercalating lignin colloid particles into the layer space of montmorillonite (MMT), and used as a synergistic agent to prepare flame‐retardant poly(butylene succinate) (PBS) composites with the incorporation of intumescent flame retardants (IFR). Using lignin colloidal nanoparticles with the particle size ranged from several to about 100 nm formed under alkali condition, the layer spacing of MMT could be exfoliated and expanded to a considerable extent. The obtained LM nanocomposites could disperse with a uniform status in PBS matrix by melt compounding. Thus, strengthened mechanical performance of composites could be achieved via replacing partial loading of IFR by LM. Besides, due to the synergetic effect between IFR and LM, the flame‐retardant properties of composites were enhanced when they were combined with an appropriate ratio. Typically, when IFR and LM loadings were 22 and 3 wt%, respectively, the tensile strength of 75P/22I/3LM increased by 24.73% in comparison with that of composite only prepared by IFR(75P/25I). Simultaneously, 36.5% of limited oxygen index (LOI) value and UL‐94 V0 rate for 75P/22I/3LM could also be achieved. TG‐IR analysis indicated that the addition of lignin increased the amount of inert gas generated. A carbonaceous silicate layer could be formed by MMT and lignin under the catalytic effect of APP, resulting in the increase of char residue after combustion. Cone calorimeter analysis demonstrated that the peak of heat release rate (pHRR), total heat release (THR) and total smoke production (TSP) of 75P/22I/3LM decreased by 57.4%, 28.7% and 33.8% compared with pure PBS, respectively.