Influence of Sepiolite and Lignin as Potential Synergists on Flame Retardant Systems in Polylactide (PLA) and Polyurethane Elastomer (PUE)

Abstract

A comparison of the influence of sepiolite and lignin as potential synergists for fire retardant (FR) systems based on ammonium polyphosphate (APP) has been carried out in polyurethane elastomer and polylactide. Different ratios of kraft lignin and sepiolite were tested in combination with APP in both polymers. The thermal stability and the fire behavior of the corresponding composites were evaluated using Thermogravimetric Analysis (TGA), a Pyrolysis Combustion Flow Calorimeter (PCFC) and Cone Calorimeter (CC). The mechanisms of flame retardancy imparted by APP and other components were investigated. Synergistic effects were highlighted but only for specific ratios between APP and sepiolite in polyurethane elastomer (PUE) and polylactide (PLA) on one hand, and between APP and lignin in PLA on the other hand. Sepiolite acts as char reinforcement but through the formation of new phosphorus compounds it is also able to form a protective layer. Conversely, only complementary effects on fire performance were noted for lignin in PUE due to a dramatic influence on thermal stability despite its action on char formation.

Multifunctional lignin-based nanocomposites and nanohybrids

“…Progress in lignin-based flame retardants was reviewed by Yang et al 415 There is a renewed interest in this research area as indicated by the studies published since their recent review. 416,417 To contribute to the development of scalable materials, synthesis of lignin-based flame retardants should increasingly rely on green and sustainable chemistry. In particular, the number of synthetic steps should be minimized along with the solvents and reagents used, and the proportion of lignin in the multicomponent flame retardants should be as high as possible.…”

Characterization and Properties of Water-Blown Rigid Polyurethane Foams Reinforced with Silane-Modified Nanosepiolites Functionalized with Graphite

“…Reports on the use of sepiolite as a halogen-free FR of PU foams are scarce [ 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. Sepiolite is a natural clay mineral of the structural family known as the 2:1 phyllosilicates, with (Si 12 Mg 8 O 30 )(OH) 4 (OH 2 ) 4 ·8H 2 O as theoretical unit cell formula [ 23 ].…”

Effect of Sepiolite-Loaded Fe2O3 on Flame Retardancy of Waterborne Polyurethane

“…Sep as a natural silicate material, which is not combustible itself, is nonpolluting to the environment and nonhazardous to human beings. However, when the material is used as flame retardant alone, the flame retardancy is not excellent [22][23][24]. For these reasons, an inorganic composite flame retardant is prepared by loading the transition metal oxide which has Lewis's acid property and could act as a kind of catalytic carbon formation agent on Sep.…”