經紫外光照射之高分子材料受溶劑引發表面波紋及色心的成長過程

The effect of UV irradiation on evolution of solvent-induced surface pattern and color center in polymers

張舜傑(Chang, Shun Chieh)

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

有關紫外光對高分子材料的影響已被廣泛討論。紫外光的照射改變高分子材料的物理性質及機械性質。本文探討聚甲基丙烯酸甲酯的光學性質及溶劑引發聚碳酸酯表面形貌的改變在紫外光效應下的變化。
照射紫外光之聚甲基丙烯酸甲酯產生色心，造成光學穿透度下降，而將試片置於高溫退火環境下，會發生色心湮滅現象使光學穿透度隨著時間而回復。假設退火過程下聚甲基丙烯酸甲酯色心湮滅的過程為一級動力學反應，建立理論模型，其與實驗結果相當吻合。所得反應速率符合阿瑞尼士方程式，反應活化能與隨著照射劑量上升而增加。
在丙酮溶劑質傳的吸收/除吸收/再吸收過程後，聚碳酸酯產生兩個區域:外層溶脹的結晶區及內層的玻璃態區，其雙層結構產生應力不均，隨溶劑質傳過程在表面產生壓應力/張應力/壓應力，進而引發規律性的表面波紋。我們分析質傳時間、溫度及紫外光劑量等參數對此表面波紋的影響。其波紋波長隨著吸收時間增加、溫度增高而變長，但隨著紫外光劑量增加而減短。

關鍵字

紫外光 ； 色心 ； 聚碳酸酯 ； 聚甲基丙烯酸甲酯 ； 丙酮質傳 ； 表面波紋

並列摘要

The effects of UV irradiation on polymer have been extensively studied. UV irradiation will change the physical and mechanical properties of polymer. We study on discoloration of poly(methyl methacrylate) and solvent-induced surface pattern of polycarbonate.
At elevated temperatures, the transmittance of UV irradiated poly(methyl methacrylate) (PMMA) increases monotonically with increasing time. The optical absorbance data found in good agreement with the theoretical model in which annealable color centers follow a first-order kinetic process. The rate constant satisfies the Arrhenius equation, with the activation energies increased slightly with the increase of dose.
After immersion/desorption/resorption processes in acetone solvent, polycarbonate becomes two regions: the swelling outer elastic layer and the glassy inner one. The swelling outer layer is constrained by the inner layer, which leads to a compressive stress. Periodic surface pattern forms during resorption. We study the effects of time, temperature, and UV dose on the swelling behavior. The morphology of the surface is observed by an optical microscope. The experimental results show that pattern wavelength increases with increasing temperature, absorption time, but decreases with increasing dose.

並列關鍵字

Ultraviolet ； color center ； Polycarbonate ； PMMA ； acetone transport ； surface pattern

參考文獻

2 B. Ranby and J. F. Rabek, “Photodegradation, Photooxidation and Photostabilization of Polymers – principles and applications ”, John Wiley & Sons Ltd, Hoboken, New Jersey, USA, pp.153-154, (1975).

3 J. F. McKellar and N. S. Allen, “Photochemisto, of Man-made Polymers”, Applied Science Publishers, London, UK, pp. 89-92, (1979).

4 A. Gupta, R. Liang, F.D. Tsay, and J. Moacanin,, “Characterization of a Dissociative Excited State in the Solid State: Photochemistry of Poly(methyl methacrylate). Photochemical Processes in Polymeric Systems. 5”, Macromolecules, vol. 13, pp. 1696-1700, (1980).

5 R.B. Fox, L. G. Isaacs, and S. Stokes, “Photolytic degradation of poly(methyl methacrylate)”. Journal of Polymer Science Part. A: General Papers., vol. 341, pp.1079–1086, (1963).

6 A. Torikai and K. Fueki, “Photodegradation of poly(methyl methacrylate) studied by ESR and viscosity measurements”, Polymer Photochemistry, vol. 2, pp.297-308, (1982).