- 學位論文
奈米鑽石/環氧樹脂複合材料之分散性與機械特性研究
Dispersion and Mechanical Properties of Nanodiamond/Epoxy Composites
摘要
複合材料是由基材與補強材組成的，環氧樹脂因為其應用範圍廣且價格低，經常被作為複合材料中的基材，再利用補強材提升其機械特性，因此本研究使用環氧樹脂為基材，奈米鑽石作為補強材製備複合材料，以定性與定量分析兩種不同方式，探討不同製程奈米鑽石在環氧樹脂中的分散性，與加入不同比例之奈米鑽石對複合材料撓曲性質與破裂韌性的影響。 研究結果顯示，超音波震盪機能有效的分散硬化劑中的奈米鑽石，加入0.1wt%奈米鑽石的補強效果最佳，相較於純環氧樹脂。撓曲強度與模數分別提升了2.34% 與12.11%，臨界第一模式應力強度因子提升96.3%。加入0.3 wt%奈米鑽石後複合材料撓曲強度與模數能更進一步提升，強度與模數分別提升10.71%與17.34%，但臨界第一模式應力強度因子無法繼續提升，但仍比純環氧樹脂高了44.1%。透過掃描式電子顯微鏡觀察破裂韌性試片斷面後，發現0.3 wt%複合材料奈米鑽石團聚現象較為明顯，此為臨界第一模式應力強度因子無法繼續提升的原因。有限單元法分析第一模式應力強度因子結果較實驗值高，改變各種參數分析後，發現蒲松比對第一模式應力強度因子影響最大。
並列摘要
Composites are composed of matrix and reinforcement. Epoxy, due to its wide range of applications and low prices, is often used as a matrix, and its mechanical properties can be enhanced by adding the reinforcement. In this study, nanodiamond/epoxy composites were prepared and qualitative and quantitative analyses are used to investigate the dispersion of nanodiamond/epoxy composites. Also the flexural properties and fracture toughness of nanodiamond/epoxy composites are discussed with different wt% nanodiamond. The results show that the dispersion of nanodiamond is improved by using sonication machine to mix the nanodiamond and curing agent. Reinforcement effect achieves to a maximum when 0.1wt% nanodiamond is added. The flexural strength, modulus and the critical mode I stress intensity factor of nanodiamond/epoxy composites with 0.1 wt% nanodiamond increase 2.34%, 12.11% and 96.3%, respectively, when compared with pure epoxy. When 0.3 wt% nanodiamond is added, the flexural strength and modulus increase 10.71% and 17.34%, respectively; the critical mode I stress intensity factor of nanodiamond/epoxy composites improves 44.1%, when compared with pure epoxy. After fracture toughness test, the SEM was used to investigate the fracture surface of nanodiamond/epoxy specimens, and obviously agglomerate nanodiamond in 0.3 wt% nanodiamond/epoxy composites was observed. This is the reason why the critical mode I stress intensity factor could not further increase. Finally, the results of mode I stress intensity factor by finite element analysis is about 40% higher than the experimental results. After examining several parameters, the results show that the Poisson’s ratio has significant influence on the mode I stress intensity factor.