Enhancing the Properties of Sodium Alginate with a Glycerol–Silicate Plasticizer

The impact of a glycerol–silicate (GS) plasticizer on the mechanical, thermal and hydrophobic properties pertaining to sodium alginate (NaAlg) and calcium alginate (CaAlg) films were investigated. Spectroscopic and physio-chemical analysis were conducted to evaluate the effects of the GS incorporation. The results determine that both NaAlg and CaAlg films exhibited poor mechanical properties which only improved by increasing the GS loading (up to 25 wt%), after which it declined. CaAlg exhibited the highest tensile strength after 25 wt% GS loading was incorporated. The elongation at break varied, with NaAlg films showing a ~10-fold increase, while the CaAlg films remained relatively unchanged. Thermal gravimetric analysis (TGA) revealed that GS reduced the onset decomposition temperature of NaAlg films, whereas CaAlg films maintained a greater onset decomposition temperature. The advancing contact angle measurements indicated a nearly linear decrease (from 54° to 39°) in hydrophobicity for the NaAlg films while the hydrophobicity for CaAlg films initially increased from 65° to 74°, and then became more hydrophilic with greater GS loading. These findings highlight the potential of GS plasticization to enhance and tailor alginate film properties, providing insights into the development of sustainable bioplastics with improved mechanical properties.