Thermal, mechanical, and rheological properties of micro-fibrillated cellulose-reinforced starch foams crosslinked with polysiloxane-based cross-linking agents.

The disposal of non-degradable plastic packaging and plastic pollution are widespread environmental problems. The development of a fully biodegradable alternative foam packaging with excellent water barrier properties from polysaccharides is quite challenging. In this work, micro-fibrillated cellulose fiber-reinforced starch foams (MFC-SFs) were developed by crosslinking with two poly(siloxane)-based crosslinking agents that enhanced their strength and water barrier properties. The polysiloxane crosslinking agents studied were a cationic trimethylsiloxy-terminated poly(aminoethyl aminopropyl methyl siloxane)-co-poly(dimethylsiloxane) or PAEAPS-co-PDMS, and a non-ionic siloxy-terminated poly(dimethylsiloxane) or TMS-t-PDMS. The applied dosage of polysiloxane crosslinking agents was varied from 1.33 to 5.32% to achieve the optimum strength and moisture barrier properties. The results show that the tensile strength increased from 1.78 MPa for the control to 2.76 MPa for the MFC-SF crosslinked with 5.32% PAEAPS-co-PDMS. The corresponding tensile strength for the MFC-SF crosslinked with TMS-t-PDMS was 2.53 MPa, which is still considerably higher than the control MFC-SF. The water absorption also decreased from 326.8% for the control to 102.5% and 79.8% for the MFC-SFs crosslinked with 5.32% PAEAPS-co-PDMS and TMS-t-PDMS respectively. The crosslinking of MFC-SFs with TMS-t-PDMS provided better hydrophobicity compared to the crosslinking with PAEAPS-co-PDMS. The developed packaging could be a promising alternative to non-degradable foam packaging.