High barrier composite films prepared from polyvinyl alcohol/lignin/montmorillonite blends

In this work, the covalent crosslinked polyvinyl alcohol (CPVA) was blended with montmorillonite (MMT) adsorbing quaternary ammonium lignin (QAL) in an exfoliated state (QAL-MMT) to prepare high barrier biodegradable composite films (QMCPVA) with good performance. Specifically, QAL, QAL-MMT, CPVA and QMCPVA composite films were firstly prepared and characterized by FTIR, XRD and SEM, etc. QAL-MMT existed in an exfoliated state within CPVA and a cross-linking network structure was formed between the two, but the lamellar structure of QAL-MMT also restricted the transfer of CPVA chains. Therefore, when the QAL-MMT additive amount was 12 %, the tensile strength of QMCPVA films can reach 59.9 MPa and the corresponding elongation at break was 82 %. Because the formation of ordered nanolayer structure can effectively hinder the diffusion of water and oxygen molecules, the water vapor transmission rate and oxygen permeability of QMCPVA composite films decreased to 49 g/m2·d and 2.2 × 10–5 cm3/m2·d·Pa, respectively. Moreover, the addition of QAL-MMT can also endow the QMCPVA films with additional antioxidant and ultraviolet shielding properties. This work would broaden the high value-added application of lignin into food and pharmaceutical packaging material field, having a great economic and environmental benefit. A high barrier biodegradable QMCPVA composite film with a brick-wall structure was prepared by blending the crosslinked PVA (as a polymer film matrix) and QAL-MMT (as fillers). • High barrier biodegradable QMCPVA composite films were prepared in this work. • The introduction of QAL-MMT caused the formation of a brick-wall structure in QMCPVA. • The mechanical and barrier properties of QMCPVA films were improved by QAL-MMT. • The QMCPVA films also had good antioxidant and ultraviolet shielding properties.