VALORIZATION OF LIGNIN MODIFIED BY HYDROXYMETHYLATION TO ENSURE BIRCH VENEER BIOPROTECTION

摘要

The present paper focused on the effect of unmodified and modified lignins and copper ions on the interaction between birch veneer and some biocides. The aim of the present study was to modify commercial lignins (Protobind 1000, Protobind 2000, Protobind 3000) by the hydroxymethylation reaction in an alkaline medium and to describe the lignin derivatives by chemical, spectral (H-1 NMR) and thermal analyses (TG). The studies revealed some functional changes, which are correlated with both the different reactivity of lignins and the reaction conditions. Also, lignin derivatives were observed by thermal analysis, which allowed establishing a correlation between the modification degree and the thermal stability. Treatments with unmodified and hydroxymethylated lignins were applied to birch veneer strips by immersing them in copper chloride solutions. The lignin products were dissolved in 0.1 N ammonia solution of 5% concentration. The biostability of the treated veneer was tested by burying the product in the soil for six months. The samples were then characterized as to their weight loss of and contact angle values. The obtained results show that the treatment of veneer with a complex of hydroxymethylated lignin derivatives and copper ions determines higher stability of the wood substrate, compared to the treatment with unmodified products.