Chemical modification of MWCNTs via oxidation followed by side wall functionalization using polyethylene glycol （PEG） and octadecylamine （ODA）, separately, was studied. Different characterization techniques such a...Chemical modification of MWCNTs via oxidation followed by side wall functionalization using polyethylene glycol （PEG） and octadecylamine （ODA）, separately, was studied. Different characterization techniques such as FTIR spectrometery, thermogravimetric analysis （TGA）, scanning electron microscopy （SEM）, X-ray diffraction （XRD）, and solubility in different solvents were performed for the oxidized MWCNTs, MWCNTs-PEG and MWCNTs-ODA. The characterization techniques proved the presence of the functional groups on the MWCNTs surface. Thermal gravimetric analysis revealed that nearly 16% （by weight） of the MWCNTs were functionalized with PEG and 39% （by weight） was functionalized with ODA.展开更多
Biodegradable polymers such as poly(butylene adipate-coterephthalate)(PBAT)have attracted great interest as alternatives to traditional petroleum-based polymers.Nonetheless,it is necessary to improve some properties o...Biodegradable polymers such as poly(butylene adipate-coterephthalate)(PBAT)have attracted great interest as alternatives to traditional petroleum-based polymers.Nonetheless,it is necessary to improve some properties of PBAT,such as mechanical strength.Cellulose nanofiber(CNF)can improve PBAT mechanical strength,but its dispersion and compatibility in the PBAT matrix require further improvement.In this study,octadecylamine(ODA)was utilized to graft-modify CNF to change the fiberto-fiber interaction and improve its compatibility with the PBAT matrix.PBAT composites with 1 wt%CNF were prepared using a masterbatch premixing method to avoid CNF aggregation during extrusion.The effects of ODA graft modification on CNF properties were studied;varying degrees of CNF modification were investigated for their effect on PBAT properties.ODA-modified CNF(OCNF)/PBAT melt-extruded composites possessing 17.2%higher tensile strength than pure PBAT polymer were obtained without affecting the thermal stability of PBAT.As a result,surface modification of CNF with ODA is an effective strategy for improving CNF-PBAT compatibility.展开更多
Natural graphite was chemically modified by an acid mixture (H2SO4/HNO3, 4:1) using sonication. The resulting material was then expanded with octadecylamine by the dispersion method. The sample was characterized by sc...Natural graphite was chemically modified by an acid mixture (H2SO4/HNO3, 4:1) using sonication. The resulting material was then expanded with octadecylamine by the dispersion method. The sample was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry (TG), wide-angle X-ray diffraction (WAXD) and relaxometry—low-field nuclear magnetic resonance (LFNMR). The SEM images revealed the expansion of the graphite layers. The presence of CH absorption was detected in the infrared spectrum of the expanded sample. The WAXD showed an additional diffraction peak at lower 2θ angle, indicating that intercalation of octadecylamine was successful. The thermogravimetry curve revealed three degradation steps. Two of them could be attributed to different structures (delaminated and exfoliated). The relaxometry showed that the relaxation time was dependon the frequency and the curve of the graphite/octadecylamine presented two peaks—approximately before 106 Hz and after 107 Hz. The results permitted inferring that organically modified graphite was achieved.展开更多
Mesoporous titania with anatase crystal framework was generated directly by ho mogeneous precipitation method using titanium sulfate (Ti(SO4)2) mixed with urea as precursor and octadecylamine (C18H37NH2) as structure-...Mesoporous titania with anatase crystal framework was generated directly by ho mogeneous precipitation method using titanium sulfate (Ti(SO4)2) mixed with urea as precursor and octadecylamine (C18H37NH2) as structure-directing agent. The as-synthesized titania has been characterized by XRD, TEM, FT-IR and N2 adsorp tion-desorption isotherm. The results displayed a wormhole-like anatase mesost ructure lacking of long-range order with BET surface area of 35m2·g-1, pore v olume of 0.1cm3·g-1 and broader pore size distribution including microporous a nd mesoporous domain. C18H37NH2 incorporated into the as-synthesized oxide.展开更多
The anti- corrosion performance of iron is greatly improved after octadecylamine (ODA) treatment. It is assumed from AES that the structure of surface layer of samples treated with ODA is as follows: Lower ODA concent...The anti- corrosion performance of iron is greatly improved after octadecylamine (ODA) treatment. It is assumed from AES that the structure of surface layer of samples treated with ODA is as follows: Lower ODA concentration: iron | iron oxide | ODA layer with iron oxide Higher ODA concentration: iron | iron oxide | ODA layer with iron oxide | pure ODA layer It is shown from infrared specular reflection that the surface layer of iron treated with higher ODA concentration reflects ν (CH) absorption peak corresponding to pure ODA layer. Every ν (CH) absorption peak shows opposite absorption phenomenon because of reflection from the iron oxide, which is under the pure ODA layer.Photoelectrochemical study exhibits that ODA treatment leads to the changes in physical structure of iron oxide layer. ODA treatment was successfully applied to lay- up protection in power plant.展开更多
文摘Chemical modification of MWCNTs via oxidation followed by side wall functionalization using polyethylene glycol （PEG） and octadecylamine （ODA）, separately, was studied. Different characterization techniques such as FTIR spectrometery, thermogravimetric analysis （TGA）, scanning electron microscopy （SEM）, X-ray diffraction （XRD）, and solubility in different solvents were performed for the oxidized MWCNTs, MWCNTs-PEG and MWCNTs-ODA. The characterization techniques proved the presence of the functional groups on the MWCNTs surface. Thermal gravimetric analysis revealed that nearly 16% （by weight） of the MWCNTs were functionalized with PEG and 39% （by weight） was functionalized with ODA.
基金financial support from the National Key Research and Development Program of China (Grant Nos. 2017YFB0307901 and 2017YFE010 2500)
文摘Biodegradable polymers such as poly(butylene adipate-coterephthalate)(PBAT)have attracted great interest as alternatives to traditional petroleum-based polymers.Nonetheless,it is necessary to improve some properties of PBAT,such as mechanical strength.Cellulose nanofiber(CNF)can improve PBAT mechanical strength,but its dispersion and compatibility in the PBAT matrix require further improvement.In this study,octadecylamine(ODA)was utilized to graft-modify CNF to change the fiberto-fiber interaction and improve its compatibility with the PBAT matrix.PBAT composites with 1 wt%CNF were prepared using a masterbatch premixing method to avoid CNF aggregation during extrusion.The effects of ODA graft modification on CNF properties were studied;varying degrees of CNF modification were investigated for their effect on PBAT properties.ODA-modified CNF(OCNF)/PBAT melt-extruded composites possessing 17.2%higher tensile strength than pure PBAT polymer were obtained without affecting the thermal stability of PBAT.As a result,surface modification of CNF with ODA is an effective strategy for improving CNF-PBAT compatibility.
基金We would like to thank the Brazilian research agencies CNPq and CAPES for financial support
文摘Natural graphite was chemically modified by an acid mixture (H2SO4/HNO3, 4:1) using sonication. The resulting material was then expanded with octadecylamine by the dispersion method. The sample was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry (TG), wide-angle X-ray diffraction (WAXD) and relaxometry—low-field nuclear magnetic resonance (LFNMR). The SEM images revealed the expansion of the graphite layers. The presence of CH absorption was detected in the infrared spectrum of the expanded sample. The WAXD showed an additional diffraction peak at lower 2θ angle, indicating that intercalation of octadecylamine was successful. The thermogravimetry curve revealed three degradation steps. Two of them could be attributed to different structures (delaminated and exfoliated). The relaxometry showed that the relaxation time was dependon the frequency and the curve of the graphite/octadecylamine presented two peaks—approximately before 106 Hz and after 107 Hz. The results permitted inferring that organically modified graphite was achieved.
文摘Mesoporous titania with anatase crystal framework was generated directly by ho mogeneous precipitation method using titanium sulfate (Ti(SO4)2) mixed with urea as precursor and octadecylamine (C18H37NH2) as structure-directing agent. The as-synthesized titania has been characterized by XRD, TEM, FT-IR and N2 adsorp tion-desorption isotherm. The results displayed a wormhole-like anatase mesost ructure lacking of long-range order with BET surface area of 35m2·g-1, pore v olume of 0.1cm3·g-1 and broader pore size distribution including microporous a nd mesoporous domain. C18H37NH2 incorporated into the as-synthesized oxide.
文摘The anti- corrosion performance of iron is greatly improved after octadecylamine (ODA) treatment. It is assumed from AES that the structure of surface layer of samples treated with ODA is as follows: Lower ODA concentration: iron | iron oxide | ODA layer with iron oxide Higher ODA concentration: iron | iron oxide | ODA layer with iron oxide | pure ODA layer It is shown from infrared specular reflection that the surface layer of iron treated with higher ODA concentration reflects ν (CH) absorption peak corresponding to pure ODA layer. Every ν (CH) absorption peak shows opposite absorption phenomenon because of reflection from the iron oxide, which is under the pure ODA layer.Photoelectrochemical study exhibits that ODA treatment leads to the changes in physical structure of iron oxide layer. ODA treatment was successfully applied to lay- up protection in power plant.
