紫外光對聚甲基丙烯酸甲酯/多壁奈米碳管複合材料的質傳和機械性質的影響

The effects of ultraviolet irradiation on mass transport and mechanical properties of poly(methyl methacrylate) / multiwalled carbon nanotubes composites

許哲銓(Hsu, Je Chuan)

指導教授 ： 李三保

國立清華大學/工學院/材料科學工程學系/碩士(2015年)

摘要

溶劑在高分子的質傳現象可分為三種:(1)第一級擴散、(2)第二級擴散與(3)不正常擴散現象。大多數高分子在溶劑中的質傳行為是屬於結合第一級與第二級擴散的不正常擴散，而Harmon 質傳模型成功地將這類擴散行為以數學形式模擬出來。而我們就以此模型來模擬PMMA多壁碳管複合材料在甲醇中的質傳行為並計算出其擴散係數(D)以及擴散速率(v)。發現PMMA加越多的碳管含量，其質傳的速度越快，代表甲醇越容易進入至有加入碳管的PMMA裡，此現象皆可由D與v觀察出來。
在照射紫外光後，高分子會因光降解現象而高分子鏈交聯或斷裂，而這些情形都會使得高分子光學以及機械性質劣化。但如果加入奈米碳管形成高分子碳管複合材料後，我們欲觀察其光降解現象是否有改變。再透過質傳的實驗與模擬，發現加入碳管的PMMA複合材料在照射紫外光後，相對於純PMMA在質傳速率上，有著較小的變化幅度，因此判斷紫外光造成高分子光降解的效應可藉由加入碳管而減弱，因此在爾後，我們陸續進行相關的實驗與檢測來證實此現象。

關鍵字

高分子 ； 奈米碳管 ； 複合材料 ； 質傳

並列摘要

The interaction between solvent and PMMA had been studied for several decades. The mass transport of amorphous polymer in organic solvent can be classified as three types: (1) Case I transport, (2) Case II transport and (3) anomalous diffusion. Most polymers in solvent are anomalous transport which combines Case I and Case II transport. Harmon et al. excogitated a theoretical model which was applied successfully to PMMA specimen of finite size. We use Harmon model to fit the mass transport of methanol and CNTs/PMMA composites. The characteristic parameters of diffusion coefficient (D) and velocity (v) are calculated from the data of curve fitting, and satisfy the Arrhenius equation. At larger content of CNTs, the composites have higher rate of mass transport, which can be confirmed from the larger value of D and v. And it explains that the solvent methanol is easier to penetrate into the polymers with carbon nanotubes.

The photochemical defragmentation reactions of poly(methyl methacrylate) (PMMA) by UV-illumination are mainly-classified as main chain scission, complete or incomplete side chain cleavage and direct UV-depolymerization. From the previous studies, it has been confirmed that UV irradiation degrades mechanical and optical properties of PMMA. After adding carbon nanotubes into PMMA becoming nanocomposites, we wanted to investigate the effects of UV irradiation on the CNTs/PMMA nanocomposites. Thus we study the relation between mass transport of PMMA with different contents of CNTs, and expose these CNTs/PMMA composites to UV irradiation. Through observing the change of mass transport, UV irradiation has much impact on the pure PMMA. The rate of mass transport increases rapidly after irradiation. In contrast, the CNTs/PMMA composites exhibit less degree of UV irradiation effect from the slightly change of mass transport.

並列關鍵字

Polymer ； Carbon nanotubes ； Composites ； Mass transport

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