| Summary: | 碩士 === 國立臺灣科技大學 === 材料科學與工程系 === 106 === Nanomaterials have numerous commercial and technological applications in chemical, biomedical, optoelectronics, electronics and space industries. Once nanomaterials are released into the environment via manufacturing, use or disposal, their transport is the critical parameter in assessing their exposure and impact on the public health and the ecosystem, therefore understanding the fate of nanomaterials in the environment is critical. This research goal aims at developing nanomaterials derived from natural resources, both reinforcement and matrix are biobased and biodegradable. Cellulose nanofibers from wood, plants and agricultural by-products is an abundant renewable resources. The fabrication of cellulose based-nanocomposite film without affecting the optical, mechanical and thermal properties of cellulose triacetate (CTA), one of the most widely used polymers, and cellulose nanofiber (CNF), which represent the world’s most abundant bio-based nanofiller, is investigated. In this study, using recycled the polarizers industrial CTA film waste – recycled triacetate cellulose (rTAC), the conventional waste disposal could be improved for the environmental issues. Furthermore, the reinforcement from the raw material, which was the extraction of nanofibers consisted of sudachi residue (lemon peel) after juice extraction. Cellulose nanofiber suspension was solvent-exchanged with acetone-methanol by series of centrifuging and re-dispersing steps. After that, using the solution casting method including the mixture of rTAC film and nanofibers that was prepared by stirring in combination with ball milling technique to achieve full dispersed solution, was coated on the glass to obtain a thin film. And for comparative purposes, industrial cellulose nanofiber (OJI-CNF) in its pristine form, is also reported. The structure of nanofibers and the dispersion effect of both CNFs in TAC were observed by scanning electron micrograph (SEM) and transmission electron microscopy (TEM). The optical, mechanical and thermal properties of the nanocomposite films were characterized experimentally. The results showed that by varying nanofiber contents (1~7wt%), the haze was slightly increased while the transmittance was not be affected compared to that of rTAC film (92.7%). On the other hand, OJI-CNF showed a lower transparency significantly when increasing nanofiber contents, compared to lemon peel-CNF, indicated that the poor dispersion due to the aggregates of OJI-CNF in solution. It was found that the addition of CNFs increased the tensile stress by 60%; the tensile strain by 150% and the yield stress by 50%. The dynamic mechanical properties (creep behavior) results were also positive; the creep compliance improved for all nanocomposites compared to rTAC film. These both nanofibers contributed to a significant reduction in the thermal expansion properties of rTAC film while maintaining their ease of bending.
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