Lignosulfonate as reinforcement in polyvinyl alcohol film: Mechanical properties and interaction analysis

• Polyvinyl alcohol (PVA) mechanical properties were enhanced significantly by only 5 wt% lignosulfonate addition.
• The strong interactions were quantitatively determined by q value of −62.4 ± 10.0 in Kwei equation.
• The interactions are formed from hydrogen bond.
• Studies on lignin-based blends can broaden its industrial utilization.

Recently, there has been a growing research interest on renewable composite due to sustainability concerns. This work demonstrated the possibility of using eucalyptus lignosulfonate calcium (HLS) particles as reinforcement in polyvinyl alcohol (PVA) matrix. 41% and 384.7% improvement of pure PVA tensile strength and Young's modulus were achieved with incorporation of 5 wt% HLS. The above results were ascribed to specific intermolecular interactions between HLS and PVA, suggested by the increasing PVA glass transition and crystalline relaxations temperature, depression of melting point with HLS incorporation. Moreover, this interaction was quantitatively determined by q value of −62.4 ± 10.0 in Kwei equation. Additionally, the remarkable red shift of wavenumber corresponding to hydroxyl group also indicated the formation of strong hydrogen bond in HLS/PVA blend. SEM characterization confirmed that HLS/PVA blends are at least miscible.