Effect of the material structure and nanoadditive type on the thermal properties of nanocomposite alginate fibres

Thermal properties of sodium alginate and calcium alginate fibres containing nanoadditives were analysed. Thermal decomposition of fibres based on sodium alginate, both pure and containing nanoadditive, produces sodium carbonate (for fibres without nanoadditive) or, for modified fibres, a mixture of sodium carbonate with the corresponding nanoadditive, which does not undergo any changes within the range of measured temperatures. The chief gaseous products accompanying the decomposition are carbon (IV) oxide and water. The shape of the DTG curves and values of the *T ₅₀ coefficient indicate an improvement in the thermal properties of the fibres when ceramic nanoadditives (SiO₂ and HAp) are introduced, as compared with pure sodium alginate fibres. When ceramic nanoadditives (MMT, SiO₂, bioglass) are added to the material of calcium alginate fibres the nature of the thermal processes is not affected. However, similarly as for sodium alginate fibres modified with nanoadditive, here also it was note the effect on the value of the *T ₅₀ coefficient. The greatest thermal stability, expressed by the value of *T ₅₀, was observed when SiO₂, HAp and bioglass were used as nanoadditives. Considering that the porosity, sorption properties and cross section were similar for all fibres, it can be suggested that in all cases the structure of the fibres has a lesser effect than the type of nanoadditive on the thermal properties of the investigated fibres. The effect of the chemical structure of the material was reflected in the higher decomposition temperature of calcium alginate nanocomposite fibres compared with sodium alginate fibres. This also applies to fibres without any nanoadditive.