石墨烯/聚合物複合材料已開發成輕量化的導電材料，而聚甲基丙烯酸甲酯由於其尺寸穩定性及生物相容性，已被普遍應用於電化學中複合材料的支撐膜。近幾年來，聚甲基丙烯酸甲酯/官能基化石墨烯(PMMA/FGs)複合材料則廣泛運用在各項領域，其中包含電子材料中的感測器、生醫材料中的人工關節等，因此研究聚合物複合材料的結構缺陷對於聚合物複合材料的應用具有實際意義，如工作環境以及使用壽命等。本實驗中分別比較了不同紫外光劑量的PMMA/FGs先浸泡50 ℃的甲醇，然後浸泡在2-乙基己醇(2EA)、環己醇和正丁醇所引起的裂縫成長，以及無預先浸泡甲醇，直接浸在50 ℃以上的2-乙基己醇、環己醇和正丁醇的情形。
PMMA/FGs複合材料的本質黏度和玻璃轉化溫度都會隨著石墨烯濃度的增加而升高，其結果乃因石墨烯阻止高分子鏈移動。然而經紫外光照射後都會降低，其結果是因為紫外光照射後，PMMA斷鏈導致分子量降低。此外，FTIR結果推測溶劑進入複合材料是擴散行為。
已預先浸泡甲醇的PMMA/FGs複合材料中的裂紋面密度和單一裂紋的生長速率隨著2EA和環己醇的浸泡時間和溫度增加而增加，其裂紋成長的機制為甲醇的析出所主導，浸入正丁醇的FGs/PMMA複合材料在50℃以下時有最大的裂紋面密度，然而在50℃以上則會最小，原因在於正丁醇會再次擴散進到材料中，這時裂紋成長反而由正丁醇所主導，正丁醇溶劑在50℃以下時有最快的單一裂紋成長速率，50℃以上則最慢，活化能的大小在50 ℃以下時依序是2EA>環己醇>正丁醇。
在沒有浸泡甲醇的情況下，PMMA/FGs複合材料中的裂紋面密度和單一裂紋的生長速率都較有浸泡甲醇的小且慢，浸泡環己醇的PMMA/FGs複合材料有最大的裂紋面密度及最快的單一裂紋生長速率；浸泡在正丁醇的PMMA/FGs複合材料則最小且最慢，而活化能的大小依序是正丁醇>2EA>環己醇，且2EA、環己醇及正丁醇擴散進入FGs/PMMA複合材料的混合熱為吸熱反應，其值因不同材料而有所不同。
增加石墨烯的比例會增加裂縫成長的活化能，而增加紫外光的劑量則會降低裂縫成長的活化能。對於相同的預切複合材料而言，癒合區域的裂紋成長速率會比未裂區域更快，原因是癒合區域已被刀片預先切開，癒合後仍有殘留應力存在，使得其裂紋傳播速率更快。
另外，雖然裂紋面密度的大小跟溶劑溫度、浸泡時間、及複合材料FGs含量有關，但拉伸試驗呈現破裂應力只跟裂紋密度有關，與產生裂紋的參數無關。

FGs/polymer composite has been developed for lightweight and electrically conductive materials. Poly (methyl methacrylate) (PMMA) has been used as a supporting film for carbonaceous materials in electrochemistry due to its high dimensional stability and biocompatibility. In recent years, PMMA/FGs composite materials have been widely used in various fields, including electronic sensors and artificial joints, etc. Therefore, studying structural defects in polymer composites is practically significant on the application on polymer composites, such as service environment and life time. In this thesis, we investigated the solvent-induced crack growth of PMMA/FGs composites irradiated with different doses of UV light immersed in methanol at 50 °C for 25 minutes, and then immersed in 2-ethylhexanol (2EA), cyclohexanol and 1-butanol. Besides, we compared the situations of immersion in 2-ethylhexanol, cyclohexanol and 1-butanol at temperatures greater than 50 °C without pre-soaking methanol and soaking methanol at temperatures below 50 °C.
Both the intrinsic viscosity and glass transition temperature of PMMA/FGs composites increase with the increase of FGs concentration, since FGs prevent the movement of polymer chains. The intrinsic viscosity and glass transition temperature of PMMA/FGs composites reduce with UV dose. UV irradiation causes photodegradation and leads to polymer chain scission and molecular weight reduction. In addition, FTIR results show that the mechanism of solvent entering the composite is a diffusion.
The areal density of crack length and the single crack growth rate for PMMA/FGs composites (methanol treatment) increased with the immersion time and temperatures of 2EA and cyclohexanol. At the temperatures lower than 50 ℃, the FGs/PMMA composites immersed in 1-butanol had the largest areal density of crack length among the three solvents, which was minimum at the temperatures greater than 50 ℃. The 1-butanol solvent has the fastest single crack growth rate below 50 ℃, and the slowest above 50 ℃. The areal crack density is assumed to be proportional to amount of 2EA, cyclohexanol, and 1-butanol. The activation energy follows the sequence from large to small is 2EA>cyclohexanol>1-butanol.
In the case of no immersion in methanol, the areal density of crack length and single crack growth rate for PMMA/FGs composites are smaller and slower, respectively, than that of methanol treatment. The PMMA/FGs composites immersed in cyclohexanol have the largest crack density and the fastest single crack growth rate; the PMMA/FGs composite soaked in 1-butanol had the smallest and the slowest, respectively. We observed that the areal crack density is linearly proportional to the amount of 2EA, cyclohexanol, and 1-butanol. The activation energy follows the sequence from large to small is 1-butanol>2EA>cyclohexanol.
Increasing the FGs concentration reduces the areal density of crack length and single crack growth rate, but increasing the UV dose increases the areal density of crack length and single crack growth rate.
In addition, the areal density of crack length is related to the solvent temperature, immersion time, and FGs content. However, the tensile test shows that the fracture stress is only proportional to the crack density.

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