利用多組成無規共聚物強化高分子界面及其微結構之研究

Effect of Phase Separation Morphology on the Adhesion of PS/PMMA Interface Reinforced with Mixed Composition of Random Copolymers

簡豪慶(Hao-Ching chien)

指導教授 ： 戴子安

國立臺灣大學/工學院/化學工程學研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.00007

摘要

本研究利用苯乙烯(styrene)、甲基丙烯酸甲酯(methyl methacrylate)聚合之無規共聚物[poly(styrene-ran-methyl methacrylate) random copolymer]來強化兩不互溶高分子材料-聚苯乙烯(polystyrene, PS)/聚甲基丙烯酸甲酯(poly-metyl methacrylate, PMMA) 之界面，並藉由非對稱雙懸臂界面接著測量法(asymmetric double canter bean method, ADCB)對此界面作定量之接著強度測試。所添加之無規共聚物(random copolymer)組成分佈為f s=0.1~0.9，共有九種不同組成，其中f s為共聚物中苯乙烯(Styrene)的體積分率。
為了更有效強化界面強度，將九種不同組成之無規共聚物，依等重量比混摻於界面，實驗結果發現，確實能夠達到更強的界面接著強度，界面強度將隨著添加量增加而越強，逐漸達最大值170 J/m2，相較於任何單一組成無規共聚物之界面強化能力有更顯著之提升。實驗中亦觀察到，隨著熱處理時間(annealing time)的變改變，多組成無規共聚物強化界面的能力將有所變化。由二次離子質譜儀(second ion mass spectroscope, SIMS)縱深元素分析實驗發現，隨著熱處理時間的增長，混摻之多組成無規共聚物在彼此互相作用下，能在界面上形成組成連續變化之結構。由穿透式電子顯微鏡( transmission electron microscopy, TEM )及原子力顯微鏡(atomic force microscopy, AFM)發現，多組成無規共聚物薄膜在二維空間形成微觀之相分離結構，包括PS-rich分散相與PMMA-rich連續相，其中PS-rich分散相的大小因熱處理時間的不同將由數百奈米變化至數十奈米，此規模大小與crazing fibril相近，故分散相在大小變化的過程中，將影響craze之起始或成長的穩定性，進而改變界面接著的強度;吾人認為在熱處理的初期，界面強度升高是由於界面間welding及縱向組成重組的效應，後期之界面強度下降乃因稀釋效應縮小PS-rich分散相之結果。在破壞面分析的部分，對經非對稱雙懸臂界面接著測試破壞後的表面進行FTIR (Fourier transform infrared microscopy) - ATR表面分析，發現以多組成無規共聚物強化之界面，其塊材厚幾何效應將會影響破壞裂縫(crack)行進的方向，使破壞位置改變，而顯現出不同的界面破裂能量(Gc)。

關鍵字

聚甲基丙烯酸甲酯 ； 無規共聚物 ； 聚苯乙烯 ； 微觀之相分離 ； 界面接著

並列摘要

We have measured the fracture toughness of interface between polystyrene (PS)/poly methyl methacrylate (PMMA) using mixed composition of different random copolymers of PSf-r-PMMA1-f, where f is the volume fraction of PS in the random copolymer. Nine different composition of PS-PMMA were used with f ranging from 0.1 to 0.9. We have found the fracture toughness of interface can be significantly increased with mixed random copolymer compared with that from the copolymer of single composition. It is found that with increasing concentration of the mixed random copolymer at the interface, the Gc of the interface increase quickly and finally reaches a plateau around 140 j/m2. SIMS experiments confirmed that the mixed composition of differ- ent random copolymers organize at the interface to form an artificial composition drift .It also shows the fracture toughness of a interface with multicomponents is strongly affected by annealing time. We interpret this time-effect on Gc is related with the formation of the two dimension phase separation of the blending thin film followed by TEM and AFM technic. We suggest that fracture toughness increases with time in the beginning of annealing under the interfacial welding mechanism and the rearrangement of random copolymers at PS/PMMA interface, and decreases later with the dilute mechanism which minimizes the domain size of PS-rich island. Because such phase separation structure is submicrometer-scale, minimizing of the domain size would result in the worse stability of the initiation and the widening of PS-crazing fibril. The failure mechanism is examined by ATR-FTIR technique. This method suggests a simple method for one to effectively use random copolymers for reinforcement.

並列關鍵字

fracture to ； polystyrene ； poly methyl methacrylate

參考文獻

1. Flory, P. J., J. Chem. Phys. 1942, 10, 51.

2. Huggins, M., J. Phys. Chem. 1942, 46, 151.

3. Brown, H. R., Macromolecules 1989, 22, 2859.

4. Brown, H. R., Macromolecules 1991, 24, 2752.

6. Washiyama, J.; Creton, C.; Kramer, E. J., Macromolecules, 1992, 25, 4751.