Thermal Responses of Lignophenols

Abstract

In order to investigate typical thermal responses of a phenolic lignin-based polymer prepared from softwood, Hinoki cypress (Chamaecyparis obtusa)-lignophenol (p-cresol type, HCLC) was analyzed using thermogravimetric analysis (TGA), differential scanning calorimeter (DSC) and dynamic mechanical analysis (DMA). In addition, thermomechanical analysis (TMA) was also carried out using an “advanced penetration technique” with small Al plates on the surfaces of samples in order to investigate both viscosities and fluidities over Tg temperature regions. Results of DSC demonstrated that exothermal peaks were observed near 180 ℃ region in the 1st scans. Besides, these peaks were completely vanished and Tg was observed after the 2nd scans. In these temperature regions, only 5 % of weight losses were observed by TGA. These results implied that the exothermal peaks were due to some organized mechanisms with both cleavages of main chains without random decomposition. DMA analysis also demonstrated both low viscosities under 10³ Pa-sec and 30 K higher Tg than Tg in static process. In addition, there was a good accordance between DMA and advanced TMA concerned to viscosity. Interestingly, a heated HCLC after DMA analysis at 220 ℃ under an aerobic condition, both thermal and structural properties of HCLC changed only a little. Based on these plasticities, stabilities and relative high Tg values, softwood lignophenols were expected as good plastics materials.