A new composite flame retardant coating for cotton roving has been investigated. The proposed coating comprises natural lignin, pure carbon allotrope carbon nanotubes (CNTs) and non-toxic potassium carbonate (K₂CO₃). The series of complementary experiments, including thermogravimetric analysis, vertical burning in fire tube, limiting oxygen index (LOI) measurement and combustion in mass loss calorimeter enabled the formulation of an optimum composition including aqueous suspension with 1 wt% of CNTs, 1 wt% lignin (L) as well as 1 wt% of K₂CO₃. Applying L/CNT/K₂CO₃ on cotton roving increased LOI from 17.1 to 38.5%, decreased final mass loss and temperature during vertical burning from 100 to 78% and 457 to 190 °C, respectively. Moreover, peak heat release rate and total heat released dropped from 97.5 to 70.4 kW/m² and from 4.2 to 1.6 MJ/m², respectively . The above experiments supported by scanning electron microscopy and Raman spectroscopy allowed also the explanation of the complementary mechanisms responsible for the overall fire retardant effect.

Carbon nanotubes (CNTs) and graphene, with their unique mechanical, electrical, thermal, optical, and wettability properties, are very effective fillers for many types of composites. Recently, a number of studies have shown that CNTs and graphene may be integrated into wood–plastic composites (WPCs) and natural-fibre-reinforced polymer composites (NFPCs) to improve the existing performance of the WPCs/NFPCs as well as enabling their use in completely new areas of engineering. The following review analyses the results of the studies presented to date, from which it can be seen that that inclusion of CNTs/graphene may indeed improve the mechanical properties of the WPCs/NFPCs, while increasing their thermal conductivity, making them electroconductive, more photostable, less sensitive to water absorption, less flammable, and more thermally stable. This study indicates that the composition and methods of manufacturing of hybrid WPCs/NFPCs vary significantly between the samples, with a consequent impact on the level of improvement of specific properties. This review also shows that the incorporation of CNTs/graphene may enable new applications of WPCs/NFPCs, such as solar thermal energy storage devices, electromagnetic shielding, antistatic packaging, sensors, and heaters. Finally, this paper recognises key challenges in the study area, and proposes future work.