In this work, bio-based composites were prepared by transesterification
of different types of lignin with tung oil followed by co-polymerization
with divinylbenzene in the presence of pine wood particles. The results
obtained reveal that regardless of the source of lignin used, the
preparation of the composites was successful, with less than 20 wt
% of unreacted material recovered after Soxhlet extraction and no
residual curing detected via Differential Scanning Calorimetry (DSC).
Thermogravimetric Analysis (TGA) of the composites showed that the
addition of pine wood particles to the co-polymer decreased the overall
thermal stability of the materials due to the faster degradation rate
of cellulose and hemicelluloses in wood, in comparison to lignin.
Dynamic Mechanical Analysis (DMA) showed that the glass transition
temperature and the storage modulus (E’) of
the materials are dependent on the source of lignin employed. The
latter, when measured at room temperature, increased with the addition
of wood particles, demonstrating their reinforcing effect. Commercial
alkali lignin exhibited a 3.5-fold increase in E’
after the addition of wood particles smaller than 150 μm. Finally,
water absorption experiments and Scanning Electron Microscopy (SEM)
images suggest a good interaction between modified lignin and pine
wood particles. Overall, the strategy employed for the preparation
of lignin-based composites was successful for the different sources
of lignin used with final properties being heavily dependent on the
specific source employed.