Effect of oleic acid on improving flame retardancy of brucite in low-density polyethylene composite

Brucite was modified with oleic acid (OA) and the effect of OA on flame retardancy of brucite in low-density polyethylene (LDPE) composites was investigated. Fourier transform infrared spectroscopy, X-ray diffraction, and particle size analysis were used to examine the structural changes of the OA modified brucite. Flammability of the LDPE/brucite composites with different OA content was characterized by thermogravimetric analysis, limiting oxygen index (LOI), UL-94 test, and microscale combustion calorimetry. The results showed that when brucite was modified with OA, magnesium oleate was formed on the brucite surface. The brucite particle size and the relative intensity of the (101) diffraction peak of brucite decreased. When the content of OA and brucite in the composite were 6 and 40 phr respectively, the prepared LDPE composite displayed better flame retardancy than the corresponding OA free LDPE composite: the LOI value increased from 22.2% to 24.9%, and the peak heat release rate decreased from 678 to 546 kW/m(2). The influence of OA on the improvement of flame retardancy of brucite in LDPE/brucite composite was due to the efficient dispersion of brucite in LDPE matrix and the structural changes of brucite, caused by the reaction of OA with brucite.