In this study,the influence of sodium hydroxide(NaOH)treatment and microwave treatment of coir fibers on the mechanical and physical properties of pressed coir fiber/epoxy composite were evaluated.The composite was fa...In this study,the influence of sodium hydroxide(NaOH)treatment and microwave treatment of coir fibers on the mechanical and physical properties of pressed coir fiber/epoxy composite were evaluated.The composite was fabricated with a hand lay-up method with compression molding.Before composite fabrication,pressed coir fiber was treated with NaOH and microwave treatments.Mechanical testing(tensile,flexural,and impact testing)of the composite was conducted.Then,water absorption and thickness swelling testing are also performed.The fractured composite surface morphology after the tensile test was analyzed by scanning electronic microscopy(SEM).The results revealed that tensile,flexural,and impact strengths of composite tend to increase after NaOH treatment of coir fiber followed by microwave treatment for 10 and 20 minutes of exposure time compared to untreated fiber.However,for NaOH treatment,the tensile,flexural and,impact strengths of composite reduce.The reducing of the tensile strength of the composite is due to the agglomeration fiber occurred,which is displayed in the SEM micrograph.Furthermore,microwave treatment of fiber for 10 minutes and NaOH treatment followed by microwave treatment for 20 minutes of exposure time decreases the water absorption and thickness swelling of the composite.展开更多
The effects of H2O2 pretreatment on the surface characteristics and bioactivity of NaOH-treated NiTi shape memory alloy(SMA)were investigated by scanning electron microscopy,X-ray diffraction,X-ray photoelectron spect...The effects of H2O2 pretreatment on the surface characteristics and bioactivity of NaOH-treated NiTi shape memory alloy(SMA)were investigated by scanning electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,Raman spectra,Fourier transform infrared spectroscopy as well as a simulated body fluid(SBF)soaking test.It is found that the H2O2 pretreatment can lead to the direct creation of more Ti—OH groups and the decrease in the amount of Ni2O3,Na2TiO3 and remnant NiTi phases on the surfaces of bioactive NiTi SMA prepared by NaOH treatment.As a result,the induction period of apatite formation is shortened by dispensing with the slow kinetic formation process of Ti—OH groups via an exchange of Na+ ions from Na2TiO3 phase with H3O+ ions in SBF,which indicates that the bioactivity of NaOH-treated NiTi SMA can be further improved by the H2O2 pretreatment.展开更多
NiTi samples were hydrothermally treated in NaOH at 200℃ with different soaking times. The morphology of the surface layer formed was studied by scanning electron microscopy (SEM). The composition of the layer and th...NiTi samples were hydrothermally treated in NaOH at 200℃ with different soaking times. The morphology of the surface layer formed was studied by scanning electron microscopy (SEM). The composition of the layer and the major phases present were determined by energy-dispersive spectroscopy (EDS) and X-ray diffractometry (XRD), respectively. In contrast to the results reported by some authors, the surface layer was essentially Ni(OH)2 instead of being TiO2. The electrochemical behavior of the samples was studied by electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution at 23℃, and analyzed using a simplified Randle circuit consisting of a resistance R and a capacitance C in parallel. After hydrothermal treatment, R was increased by a factor ranging from 1.5 to 5.0 times, depending on the treatment time. The value of R of all the samples became steady within a period of less than 15 h. Results of the present study indicate that alkaline treatment leads to the growth of an insulating layer on NiTi, but the method is not suitable for surface modification of NiTi implants due to the enhanced Ni content in the surface layer.展开更多
文摘In this study,the influence of sodium hydroxide(NaOH)treatment and microwave treatment of coir fibers on the mechanical and physical properties of pressed coir fiber/epoxy composite were evaluated.The composite was fabricated with a hand lay-up method with compression molding.Before composite fabrication,pressed coir fiber was treated with NaOH and microwave treatments.Mechanical testing(tensile,flexural,and impact testing)of the composite was conducted.Then,water absorption and thickness swelling testing are also performed.The fractured composite surface morphology after the tensile test was analyzed by scanning electronic microscopy(SEM).The results revealed that tensile,flexural,and impact strengths of composite tend to increase after NaOH treatment of coir fiber followed by microwave treatment for 10 and 20 minutes of exposure time compared to untreated fiber.However,for NaOH treatment,the tensile,flexural and,impact strengths of composite reduce.The reducing of the tensile strength of the composite is due to the agglomeration fiber occurred,which is displayed in the SEM micrograph.Furthermore,microwave treatment of fiber for 10 minutes and NaOH treatment followed by microwave treatment for 20 minutes of exposure time decreases the water absorption and thickness swelling of the composite.
基金Project(50501007) supported by the National Natural Science Foundation of ChinaProject(BK2003062) supported by the Natural Science Foundation of Jiangsu Province,China+2 种基金Project(CityU 1/04C) supported by Hong Kong Research Grants Countil(RGC) Central Allocation Group ResearchProject(4012001007) supported by Teaching and Research Award Program for Outstanding Young Teachers of Southeast UniversityProject(9212001352) supported by Pre-research Project for National Natural Science Foundation in Southeast University,China
文摘The effects of H2O2 pretreatment on the surface characteristics and bioactivity of NaOH-treated NiTi shape memory alloy(SMA)were investigated by scanning electron microscopy,X-ray diffraction,X-ray photoelectron spectroscopy,Raman spectra,Fourier transform infrared spectroscopy as well as a simulated body fluid(SBF)soaking test.It is found that the H2O2 pretreatment can lead to the direct creation of more Ti—OH groups and the decrease in the amount of Ni2O3,Na2TiO3 and remnant NiTi phases on the surfaces of bioactive NiTi SMA prepared by NaOH treatment.As a result,the induction period of apatite formation is shortened by dispensing with the slow kinetic formation process of Ti—OH groups via an exchange of Na+ ions from Na2TiO3 phase with H3O+ ions in SBF,which indicates that the bioactivity of NaOH-treated NiTi SMA can be further improved by the H2O2 pretreatment.
文摘NiTi samples were hydrothermally treated in NaOH at 200℃ with different soaking times. The morphology of the surface layer formed was studied by scanning electron microscopy (SEM). The composition of the layer and the major phases present were determined by energy-dispersive spectroscopy (EDS) and X-ray diffractometry (XRD), respectively. In contrast to the results reported by some authors, the surface layer was essentially Ni(OH)2 instead of being TiO2. The electrochemical behavior of the samples was studied by electrochemical impedance spectroscopy (EIS) in 3.5% NaCl solution at 23℃, and analyzed using a simplified Randle circuit consisting of a resistance R and a capacitance C in parallel. After hydrothermal treatment, R was increased by a factor ranging from 1.5 to 5.0 times, depending on the treatment time. The value of R of all the samples became steady within a period of less than 15 h. Results of the present study indicate that alkaline treatment leads to the growth of an insulating layer on NiTi, but the method is not suitable for surface modification of NiTi implants due to the enhanced Ni content in the surface layer.
