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UBC Theses and Dissertations

Effect of organoclay reinforcement on pyrolytic-lignin-based carbon fibres Qin, Wei


Pyrolytic lignin has negative effect on the quality of bio-oil in the application as fuel and energy source. On the other hand, pyrolytic lignin is also a potential alternative precursor for the manufacturing of general performance grade carbon fibre. Since clay or layered silicate reinforcement has been demonstrated to enhance the mechanical properties of many polymers, improvement of mechanical properties of carbon fibre fabricated in this work is expected. This thesis focuses on the proof-of-concept study of pyrolytic-lignin-based carbon fibres and investigates the potential of organoclay reinforcement in improving the mechanical properties of the resultant carbon fibres. In the process of carbon fibre preparation, the pretreatment (thermal treatment under reduced pressure) was found to be a critical step in the successful preparation of carbon fibres from pyrolytic lignin. Without pretreatment, the pyrolytic lignin tended to develop hollow structures during spinning and the spun fibres fuse when thermostabilized. In the pretreatment, higher temperatures and longer time (170-180oC and 4-6 hrs) led to poor fibre spinning of pyrolytic lignin, whereas lower temperature and shorter time (150oC and 0.5-2 hrs) resulted in lignin fibres fusing in the thermostabilization process. Only a narrow window between these two extremes is suitable for carbon fibre production. By choosing the treatment condition (160°C, 30KPa for 1h) that gives the best fibre spinning, pyrolytic-lignin-based carbon fibres were fabricated, with mechanical properties and yield comparable to those based on technical lignins. Two organoclays were employed containing modifiers with different hydrophobicity. The tensile strength of carbon fibres were improved by 12% to ~440 MPa at a 1 wt% organoclay Cloisite 30B loading. Increasing the organoclay content above 1 wt% resulted in a drop in tensile strength. The Young's modulus of pyrolytic-lignin-based carbon fibres dropped slightly upon addition of both types of organoclays (~32 GPa) and decreased as organoclay content increases. The addition of organoclay only slightly increased the overall yield of carbon fibre production from 45 wt% to 46-47%, which was independent of organoclay type and loading.

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Attribution-NonCommercial-NoDerivatives 4.0 International