Search

A novel and environmentally friendly lignin-based surfactant sodium lignosulfonate (SLS) modified layered double hydroxide (LDH) flame retardant (LDH-LS) was fabricated via co-precipitation method, and subsequently incorporated into polypropylene (PP) matrix to obtain the PP and LDH-LS composites (PP/LDH-LS) by melt blending method. The XRD, FT-IR and XPS results indicated that SLS had successfully modified LDH by adsorbing on the surface of the LDH nanosheet. The WCA and SEM results revealed that the hydrophobic property of LDH-LS had been evidently improved, and it displayed a more homogeneous dispersion than virgin LDH in the PP matrix. Furthermore, cone calorimetry tests (CCT) illustrated that the peak heat release rate (PHRR), total heat release (THR), and total smoke release (TSR) of PP/LDH-LS composites exhibited declines of 62.9%, 25.1%, and 43.3% compared with those of Neat PP, respectively. Besides, the PP/LDH-LS achieved a LOI value of 29.4% and a UL-94 V-0 rating, whereas the PP/LDH showed only a LOI value of 25.2% and a UL-94 V-2 rating at 20 wt% loading. These improvements of flame retardant properties can be attributed to that the well-dispersed LDH-LS and synergistic flame retardancy between LDH and SLS. [ABSTRACT FROM AUTHOR]

In this paper, a functionalized layered double hydroxide (LDH-LS@Ni(OH) 2) flame retardant was designed and fabricated based on a multi-modifier system consisting of lignosulfonate (LS) and Ni(OH) 2 and used as a novel flame retardant for polypropylene (PP). In this multi-modifier system, LS as a compatibilizer and charring agent to improve compatibility and char yield, and Ni(OH) 2 was utilized to improve the graphitization of char residual, resulting in a PP/LDH-LS@Ni(OH) 2 composite with higher thermal stability. With the addition of LDH-LS@Ni(OH) 2 was only 15 wt%, the PP/LDH-LS@Ni(OH) 2 composite achieved a limiting oxygen index (LOI) of 30.8% and passed the UL-94 V-0 rating. At the same time, the peak heat release rate (PHRR), total heat release (THR), and total smoke production (TSP) were significantly reduced by 62.7%, 29.5%, and 46.2%, respectively. The flame retardant properties of LDH-LS@Ni(OH) 2 were mainly due to the catalytic charring effect of the transition metal elements and the physical barrier effect of the hydrotalcite. More specifically, as a highly efficient flame retardant, LDH-LS@Ni(OH) 2 has promising potential in reducing the fire hazards of PP composites. [Display omitted] • The dual modified LDH flame retardant was synthesized by co-precipitation method. • A novel hybrid flame retardant of S/Ni-containing (LDH-LS@Ni(OH) 2) was prepared. • PP/LDH-LS@Ni(OH) 2 (15 wt%) increased the LOI to 30.8% and passed the UL-94 V-0 rating. [ABSTRACT FROM AUTHOR]