The interlayer surface of MgAl layered double hydroxide （MgAl-LDH） was modified by exchanging about half of the interlayer nitrate anions by dodecyl sulfate anions （DS） to get MgAl（H-DS） LDH, and then the MgAl（...The interlayer surface of MgAl layered double hydroxide （MgAl-LDH） was modified by exchanging about half of the interlayer nitrate anions by dodecyl sulfate anions （DS） to get MgAl（H-DS） LDH, and then the MgAl（H-DS） was melt intercalated by LLDPE to get the LLDPE/MgAl-LDH exfoliation nanocomposites. The samples were characterized by Fourier transform infrared （PTIR） spectroscopy, X-ray diffraction （XRD）, ion chromatography, transmission electron microscopy （TEM）, and thermogravimetry analysis （TGA）. The nanoscale dispersion of MgAl-LDH layers in the LLDPE matrix was verified by the disappearance of （001） XRD reflection of the modified MgAl-LDH and by the TEM observation. The TGA profiles of LLDPE/MgAl-LDH nanocomposites show a faster charring process between 210 and 370 ℃ and a higher thermal stability above 370 ℃than LLDPE. The decomposition temperature of the nanocomposites with 10 wt% MgAl（H-DS） can be 42 ℃ higher than that of LLDPE at 40% weight loss.展开更多
Synergistic effects of layered double hydroxide （LDH） with intumescent flame retardanct （IFR） of phosphorusnitrogen （NP） compound in the polypropylene/ethylene-propylene-diene/IFR/LDH （PP/EPDM/IFR/LDH） nanocom...Synergistic effects of layered double hydroxide （LDH） with intumescent flame retardanct （IFR） of phosphorusnitrogen （NP） compound in the polypropylene/ethylene-propylene-diene/IFR/LDH （PP/EPDM/IFR/LDH） nanocomposites and related properties were studied by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, scanning electron microscopy （SEM）, limiting oxygen index （LOI）, UL-94 test, cone calorimeter test （CCT） and thermo-gravimetric analysis （TGA）. The XRD and TEM results show that the intercalated and/or exfoliated nanocomposites can be obtained by direct melt-intercalation of PP/EPDM into modified LDH and that LDH can promote the IFR additive NP to disperse more homogeneously in the polymer matrix. The SEM results provide positive evidence that more compact charred layers can be obtained from the PP/EPDM/NP/LDH sample than those from the PP/EPDM/LDH and PP/EPDM/NP samples during burning. The LOI and UL-94 rating tests show that the synergetic effects of LDH with NP can effectively increase the flame retardant properties of the PP/EPDM/NP/LDH samples. The data from the CCT and TGA tests indicate that the PP/EPDM/NP/LDH samples apparently decrease the HRR and MLR values and thus enhance the flame retardant properties and have better thermal stability than the PP/EPDM/LDH and PP/EPDM/NP samples.展开更多
An organo modified MgAl layered double hydroxide (OMgAl LDH) was successfully exfoliated in the xylene solution of polyethylene grafted maleic anhydride (PE g MA) under refluxing condition. A PE g MA/MgAl LD...An organo modified MgAl layered double hydroxide (OMgAl LDH) was successfully exfoliated in the xylene solution of polyethylene grafted maleic anhydride (PE g MA) under refluxing condition. A PE g MA/MgAl LDH exfoliation nano composite was formed after the precipitation of PE g MA from the dispersion system. The structure and thermal property of the PE g MA/MgAl LDH exfoliation nanocomposite were characterized by X ray diffraction (XRD), transmission electron microscopy (TEM), and thermogravimetry analysis (TGA). The disappearance of d 001 XRD peak of OMgAl LDH at 2 θ =3 2° suggests that the MgAl hydroxide sheets are exfoliated in the nanocomposite. The TEM image shows that the MgAl hydroxide sheets of less than 70 nm in length or width are exfoliated and dispersed disorderly in PE g MA matrix. TGA profiles indicate that the PE g MA/MgAl LDH nanocomposite with 5 wt% OMgAl LDH loading shows a faster charring process in temperature range from 210 to 390 ℃ and a greater thermal stability beyond 390 ℃ than PE g MA does. The decomposition temperature of the nanocomposite is 25 ℃ higher than that of PE g MA as measured at 50% weight loss. The PE g MA/MgAl LDH nanocomposite is promising for application of flame retardant polymeric materials.展开更多
基金Project supported by the National Natural Science Foundation of China （No. 50373039） and the National Key Basic Special Foundation （No. 2001CB409600） of China.
文摘The interlayer surface of MgAl layered double hydroxide （MgAl-LDH） was modified by exchanging about half of the interlayer nitrate anions by dodecyl sulfate anions （DS） to get MgAl（H-DS） LDH, and then the MgAl（H-DS） was melt intercalated by LLDPE to get the LLDPE/MgAl-LDH exfoliation nanocomposites. The samples were characterized by Fourier transform infrared （PTIR） spectroscopy, X-ray diffraction （XRD）, ion chromatography, transmission electron microscopy （TEM）, and thermogravimetry analysis （TGA）. The nanoscale dispersion of MgAl-LDH layers in the LLDPE matrix was verified by the disappearance of （001） XRD reflection of the modified MgAl-LDH and by the TEM observation. The TGA profiles of LLDPE/MgAl-LDH nanocomposites show a faster charring process between 210 and 370 ℃ and a higher thermal stability above 370 ℃than LLDPE. The decomposition temperature of the nanocomposites with 10 wt% MgAl（H-DS） can be 42 ℃ higher than that of LLDPE at 40% weight loss.
文摘Synergistic effects of layered double hydroxide （LDH） with intumescent flame retardanct （IFR） of phosphorusnitrogen （NP） compound in the polypropylene/ethylene-propylene-diene/IFR/LDH （PP/EPDM/IFR/LDH） nanocomposites and related properties were studied by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, scanning electron microscopy （SEM）, limiting oxygen index （LOI）, UL-94 test, cone calorimeter test （CCT） and thermo-gravimetric analysis （TGA）. The XRD and TEM results show that the intercalated and/or exfoliated nanocomposites can be obtained by direct melt-intercalation of PP/EPDM into modified LDH and that LDH can promote the IFR additive NP to disperse more homogeneously in the polymer matrix. The SEM results provide positive evidence that more compact charred layers can be obtained from the PP/EPDM/NP/LDH sample than those from the PP/EPDM/LDH and PP/EPDM/NP samples during burning. The LOI and UL-94 rating tests show that the synergetic effects of LDH with NP can effectively increase the flame retardant properties of the PP/EPDM/NP/LDH samples. The data from the CCT and TGA tests indicate that the PP/EPDM/NP/LDH samples apparently decrease the HRR and MLR values and thus enhance the flame retardant properties and have better thermal stability than the PP/EPDM/LDH and PP/EPDM/NP samples.
基金theNationalKeyBasicSpecialFoundation (No .2 0 0 1CB40 960 0 )ofChina
文摘An organo modified MgAl layered double hydroxide (OMgAl LDH) was successfully exfoliated in the xylene solution of polyethylene grafted maleic anhydride (PE g MA) under refluxing condition. A PE g MA/MgAl LDH exfoliation nano composite was formed after the precipitation of PE g MA from the dispersion system. The structure and thermal property of the PE g MA/MgAl LDH exfoliation nanocomposite were characterized by X ray diffraction (XRD), transmission electron microscopy (TEM), and thermogravimetry analysis (TGA). The disappearance of d 001 XRD peak of OMgAl LDH at 2 θ =3 2° suggests that the MgAl hydroxide sheets are exfoliated in the nanocomposite. The TEM image shows that the MgAl hydroxide sheets of less than 70 nm in length or width are exfoliated and dispersed disorderly in PE g MA matrix. TGA profiles indicate that the PE g MA/MgAl LDH nanocomposite with 5 wt% OMgAl LDH loading shows a faster charring process in temperature range from 210 to 390 ℃ and a greater thermal stability beyond 390 ℃ than PE g MA does. The decomposition temperature of the nanocomposite is 25 ℃ higher than that of PE g MA as measured at 50% weight loss. The PE g MA/MgAl LDH nanocomposite is promising for application of flame retardant polymeric materials.
