| Summary: | 碩士 === 逢甲大學 === 機械與電腦輔助工程學系 === 102 === Graphene has many excellent properties, and current research focuses on thermal conductivity and electrical conductivity of graphene nanocomposites; however, few researchers have studied moisture absorption properties of graphene nanocomposites. Therefore, this thesis focuses on moisture effect on mechanical properties of graphene/epoxy nanocomposites.
In this study, Hummer’s method is used to prepare graphene oxide (GO). Using hexamethylenetetramine (HMTA) graphene oxide (GO) can be reduced as reduced graphene oxide (RGO). With addition of GO and RGO into epoxy, GO/Epoxy and RGO/Epoxy nanocomposites can be fabricated. In order to promote dispersion of GO and RGO in Epoxy matrix, a dispersant acetone is added to the nanocomposites to fabricate Acetone/GO/Epoxy and Acetone/RGO/Epoxy nanocomposites. Weight fraction of GO or RGO relative to the weight of the epoxy is adjusted to be 0.5wt%, 1wt%, 1.5wt%, 2wt%, and 3wt%. To study moisture effect on nanocomposites, the nanocomposites are soaked in the deionized water or normal saline for 24 hours, 48 hours, 72 hours, 100 hours, 400 hours, 30 days, and 60 days. The relationship between tensile strength and water gain percentage of composites is explored, and FESEM is used to observe failure modes of tested specimens.
Tensile strength and Young&;#39;s modulus of composites increase with weight fraction of GO or RGO reinforcements. Tensile strengths of GO(3wt%)/Epoxy, RGO(3wt%)/Epoxy, and Epoxy are respectively 43.54 MPa,50.65 MPa, and 22.35 MPa. The dispersant acetone can improve the dispersion of GO or RGO in the matrix and increase tensile strength of composites. Therefore, tensile strengths of acetone(10wt%)/GO(3wt%)/Epoxy, acetone(10wt%)/RGO(3wt%)/Epoxy are respectively 47.26 MPa and 56.83 MPa. The longer the soaking time in the liquid, the lower the tensile strength of the composite is acetone/RGO(0.5wt%)/epoxy. For acetone/RGO(0.5wt%)/epoxy composites soaked in normal saline for 60 days, it has lowest tensile strength of 12.17MPa among all composites. It is found that thin nanocomposites tend to wrinkle and twist easily when soaked in liquid, and the liquid also causes interfacial interaction between the reinforcing materials and epoxy matrix. Besides, the water gain percentage of nanocomposites decreases with increasing reinforcement weight fraction.
|
|---|
