STUDIES ON THE THERMOPLASTICIZATION OF WOOD

Lauroylated wood meal was prepared in a DMF-pyridine and in a N2O4-DMF-pyridine medium for subsequent thermoplasticization of wood. The thermal softening äs well äs the melting of the chemically-modified wood were studied by measuring the deformation of the samples under a constant load at a programmed heating rate, by measuring the dielectric relaxation and by observation with SEM. The diagram of the relationship between deformation and temperature shows three specific starting points of thermal deformation, T1, T2 and T3. T3 was observed only in the suificiently thermoplasticized wood meal. T1 corresponds to the melting point of cellulose laurate within the wood structure, T2 to the thermal softening point of lignin, and T3 to the melting point of the treated wood meal. These three specific temperatures, each decreasing with increasing ester content, levelled off above an ester content of 90%. However, there are still significant changes at the molecular level, such äs the orientation of the acyl dipole. Thus for example, both the values of ΔE and ΔS for reorientation of the acyl dipole decrease linearly with increasing logarithm of ester content even above 90%. The melting of lauroylated wood having an ester content above 90% at the temperature of T3 was clearly confirmed by SEM observation. © Copyright by Walter de Gruyter & Co.