Thermal Stability, Combustion Behavior, and Mechanical Property in a Flame-Retardant Polypropylene System.

In order to comprehensively improve the strength, toughness, flame retardancy, smoke suppression, and thermal stability of polypropylene (PP), layered double hydroxide (LDH) Ni_0.2Mg_2.8Al-LDH was synthesized by a coprecipitation method coupled with the microwave-hydrothermal treatment. The X-ray diffraction (XRD), morphology, mechanical, thermal, and fire properties for PP composites containing 1 wt %-20 wt%Ni_0.2Mg_2.8Al-LDH were investigated. The cone calorimeter tests confirm that the peak heat release rate (pk-HRR) of PP-20%LDH was decreased to 500 kW/m² from the 1057 kW/m² of PP. The pk-HRR, average mass loss rate (AMLR) and effective heat of combustion (EHC) analysis indicates that the condensed phase fire retardant mechanism of Ni_0.2Mg_2.8Al-LDH in the composites. The production rate and mean release yield of CO for composites gradually decrease as Ni_0.2Mg_2.8Al-LDH increases in the PP matrix. Thermal analysis indicates that the decomposition temperature for PP-5%LDH and PP-10%LDH is 34 °C higher than that of the pure PP. The mechanical tests reveal that the tensile strength of PP-1%LDH is 7.9 MPa higher than that of the pure PP. Furthermore, the elongation at break of PP-10%LDH is 361% higher than PP. In this work, the synthetic LDH Ni_0.2Mg_2.8Al-LDH can be used as a flame retardant, smoke suppressant, thermal stabilizer, reinforcing, and toughening agent of PP products. [ABSTRACT FROM AUTHOR]