Excellent thermal insulation and flame retardancy property of konjac glucomannan/sodium alginate aerogel reinforced by phytic acid

Abstract

The growing social awareness of the green industry has driven the rapid development of eco-friendly insulation biomass aerogels to replace traditional ones. Natural polysaccharide aerogels have garnered significant research interest owing to their exceptional sustainability and safety. However, the challenges in achieving a harmonious combination of excellent thermal insulation and flame retardancy have impeded their practical application. In this study, a full biomass konjac glucomannan/sodium alginate aerogel was fabricated with phytic acid (PA) addition to strengthen its thermal insulation and flame retardancy properties. Results showed that the aerogel had a density of 11.8–49.2 mg/cm3 and a porosity of 95.1–98.7%. The physical cross-linking interactions of the components contributed to the formation of the pore structure. Although the analysis on the combustion, residual component, and char layer indicated a higher PA addition strengthened the flame retardancy property, it led to the appearance of micro holes on the pore wall, resulting in poorer thermal insulation properties and significantly weakened mechanical properties. Therefore the optimum PA addition was considered to be 0.25%, and the flame retardancy mechanism was proposed. The obtained aerogel exhibited a thermal conductivity as low as 0.032 W/(mK), compressive strength of 245.4 kPa, limiting oxygen index value of 29.3%, and peak heat release rate value of 21.79 W/g. These findings not only offered a kind of eco-friendly aerogel with excellent thermal insulation and flame retardancy but also contributed to the impact of PA addition on the polysaccharide aerogel structure.