| Summary: | 碩士 === 國立臺灣科技大學 === 材料科學與工程系 === 100 === This study discussed two types of biodegradable polymer composites (polylactic acid and polybutylene succinate). UV absorbers and hindered amine light stabilizers were added to prolong the life cycle of the composite fibers in outdoor lighting conditions. By using the multi-objective optimization theory of a variety of quality engineering approaches, this study examined the impact of the composite mixing process and melt spinning process on the product quality in different stages, in order to improve the innovative research relating to biodegradable fiber applications.
This study divided the planning of the development of the environmentally friendly polylactic acid composite fibers into two stages. The first stage was “applying the Taguchi method and the principal component analysis in the polylactic acid property modification process”. The aim was to discuss the impact of different material proportions, dual-screw mixing process temperature, and shearing force on the mechanical strength of polylactic acid composite materials. Moreover, this study explored major properties of polylactic acid composite materials, such as the optical properties, the thermal properties of polylactic acid before and after modification, material compatibility, processing flowability and weather resistance. The results suggested that, the addition of 10 wt% polybutylene succinate can increase the toughness of polylactic acid by 20%. Taguchi method and the principal component analysis can improve the bending strength by 27%, the tensile strength by 13.47% and the impact strength by 22.95%. Finally, after 480 h of UV aging acceleration test, the tensile strength retention rate was 94.86%, which was higher than the polylactic acid by 44%. The break extension retention rate was 85.17%, which was higher than the pure polylactic acid by 35.17%.
The second stage was “applying the response surface methodology and multi-objective particle swarm algorithm in the polylactic acid composite fiber process”. The aim was to obtain the newly spun threads by melt spinning method from the polylactic acid composite material acetate tablets under the optimal conditions of the first stage. The impact of spinning temperature, spinneret rotation speed, fiber wrapping roller on the newly spun thread quality characteristics in the fiber spinning process were also discussed. The response surface methodology was applied to establish the regression models of different quality characteristics before using the multi-objective particle swarm algorithm for the optimization processing of these quality characteristic models and parameter constraints. The experiments found that the polylactic acid/polyacid butanediol ester composite material was better than the polylactic acid/polycaprolactone composite material. The optimal composite fiber denier was 40.07 with an improvement by 5.3%. The fiber strength was 1.69(gf/d) with an improvement by 42% and elongation at break was 176.04% with an improvement by 27%. The optimal regression model prediction error rate was 5.5%, suggesting the model has a good reproductability and accuracy.
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