World Academy of Science, Engineering and Technology, International Journal of Chemical and Molecular Engineering, Feb 27, 2014
Poly (trimethylene terephthalate) (PTT) is a linear aromatic polyester with good strength and sti... more Poly (trimethylene terephthalate) (PTT) is a linear aromatic polyester with good strength and stiffness, good surface appearance, low shrinkage and war page, and good dimensional stability. However, it has low impact strength which is a problem in automotive application. Thus, modification of PTT with the other polymer or polymer blending is a one way to develop a new material with excellence properties. In this study, PTT/High Density Polyethylene (HDPE) blends and PTT/Linear Low Density Polyethylene (LLDPE) blends with and without compatibilizers base on maleic anhydride grafted HDPE (MAH-g-HDPE) and ethylene-methacrylic acid neutralized sodium metal (Na-EMAA) were prepared by a twin-screw extruder. The blended samples with different ratios of polymers and compatibilizers were characterized on mechanical and rheological properties. Moreover, the phase morphology and dispersion size were studied by using SEM to give better understanding of the compatibility of the blends.
Blends of polyamide-6 (PA-6) and high-density polyethylene (HDPE) with blend ratios of 80/20 (wt/... more Blends of polyamide-6 (PA-6) and high-density polyethylene (HDPE) with blend ratios of 80/20 (wt/wt) and 20/80 (wt/wt) were studied using zinc-neutralized maleic anhydride (MAH) grafted HDPE as compatibilizers. MAH groups were hydrolyzed and neutralized with different amounts of zinc acetate dihydrate in a twin-screw extruder to produce different levels of zinc-neutralization (0, 14, 41, 69, and 95 %) at one and ten parts per hundred of resin of compatibilizer. Melt neutralization of MAH was confirmed by X-ray fluorescence, FT–IR, and rheological properties. SEM micrographs showed a large reduction in the dispersed phase size in the compatibilized blends. Tensile measurements showed improvement of tensile strength for all compatibilized blends; moreover, the elongation at break of compatibilized blends at 10 phr of compatibilizer was improved. Blending increased the crystallization temperature for the PA-6, and the addition of compatibilizer reduced the crystallization temperature slightly. A significant increase in melt viscosity of the compatibilizer was found with zinc addition and adding compatibilizer increased the viscosity of the blends. However, the addition of zinc to the compatibilizer did not change the viscosity in the PA-6-rich blends and actually led to a decrease in viscosity in the HDPE-rich blends.
An ethylene–methacrylic acid copolymer partially neutralized with sodium (Na-EMAA) was successful... more An ethylene–methacrylic acid copolymer partially neutralized with sodium (Na-EMAA) was successfully used to compatibilize Nylon 6 (Ny6) and low-density polyethylene (LDPE) blends. The phase morphology and thermal behavior of these blends were investigated over a range of compositions using a variety of analytical techniques. The addition of small amounts (0.5 phr) of Na-EMAA improved the compatibility of Ny6/LDPE blends as
... τactual = ) (2 nR L PR + Δ = ) /(2nRL P + Δ (3) where n is a multiplication factor according ... more ... τactual = ) (2 nR L PR + Δ = ) /(2nRL P + Δ (3) where n is a multiplication factor according to theBagley correction; and the actual shear rate γactual is defined as actual . ... Sci. 60:1736 5. Sinthavathavorn W, Nithanakul M , Magaraphan R, Grady BP (2007) J. Appl.Polym. Sci. ...
... Plast Polym 41:39–43 4. Bagley EB (1961) The separation of elastic and viscous effects in pol... more ... Plast Polym 41:39–43 4. Bagley EB (1961) The separation of elastic and viscous effects in polymer flow. ... Sinthavathavorn W, Nithitanakul M, Magaraphan R, Grady BP (2008) Blends of polyamide 6 with low-density polyethylene compatibilized with ethylenemethacrylic acid ...
Poly(D,L-lactide-co-glycolide) (PLGA) with encapsulated hydrophobic magnetite (Fe3O4) nanoparticl... more Poly(D,L-lactide-co-glycolide) (PLGA) with encapsulated hydrophobic magnetite (Fe3O4) nanoparticles or hydroxyapatite (HAp) nanoparticles were prepared by the w/o/w emulsion technique. The weight ratios of nanoparticles (Fe3O4 or HAp) to PLGA and polymer molecular weight were varied in the oil phase and the properties of the composite nanoparticles were studied. The final weight percent of nanoparticles in the spherical PLGA particles varied from ~ 5 to 60 wt%. Hydrodynamic diameters of the composite nanoparticles as measured by dynamic light scattering (DLS) were found to decrease with decreasing polymer molecular weight and were independent of nanoparticle loading. Particle sizes measured from TEM were smaller by almost a factor of two vs. those obtained from DLS. The zeta potentials of the particles were about − 23 mV, independent of polymer molecular weight and nanoparticle loading within statistical significance. In vitro cytotoxicity tests show a high level of cytocompatibility suggesting satisfactory biocompatibility for biomedical applications.
Langmuir : the ACS journal of surfaces and colloids, Jan 16, 2014
Hydroxyl groups on the surface of metal oxide nanoparticles (nps) can be protonated or deprotonat... more Hydroxyl groups on the surface of metal oxide nanoparticles (nps) can be protonated or deprotonated depending on solution pH, changing both the magnitude and sign of the nps' surface charge. Binary mixtures of fumed metal oxide nps, dispersed in water at a solution pH where one species is positively charged and the other is negatively charged, form pseudosolid gels at volume fractions as low as 1.5 vol %. This work maps out regions of gel formation for binary mixtures of silica and alumina nps, silica and titania nps, and alumina and titania nps. The microscopic structure of these gels is investigated using transmission electron microscopy (TEM), small-angle x-ray scattering (SAXS), acoustic spectroscopy, and light microscopy.
The effect of simultaneous alignment of polyethylene (PE) lamellae and graphene nanoplatelets (Gn... more The effect of simultaneous alignment of polyethylene (PE) lamellae and graphene nanoplatelets (GnP) on the thermal conductivity (k) of PE-GnP composites is investigated. Measurements reveal a large increase of 1100% in k of the aligned PE-GnP composite using 10 wt% GnPs relative to unoriented pure PE. The rate of increase of k with applied strain for the pure PE-GnP composite with 10 wt% GnP is found to be almost a factor of two higher than the pure PE sample, pointing to the beneficial effect of GnP alignment on k enhancement. Aligned GnPs are further found to be 3 times as effective in enhancing k as in the randomly oriented configuration. Enhancement in k is correlated with the alignment of PE lamellae and GnPs through wide-angle X-ray scattering and polarized Raman spectroscopy. At the maximum applied strain of 400% and using 10 wt% GnPs, a composite k of 5.9 W mK(-1) is achieved. These results demonstrate the great potential of simultaneous alignment effects in achieving high k...
World Academy of Science, Engineering and Technology, International Journal of Chemical and Molecular Engineering, Feb 27, 2014
Poly (trimethylene terephthalate) (PTT) is a linear aromatic polyester with good strength and sti... more Poly (trimethylene terephthalate) (PTT) is a linear aromatic polyester with good strength and stiffness, good surface appearance, low shrinkage and war page, and good dimensional stability. However, it has low impact strength which is a problem in automotive application. Thus, modification of PTT with the other polymer or polymer blending is a one way to develop a new material with excellence properties. In this study, PTT/High Density Polyethylene (HDPE) blends and PTT/Linear Low Density Polyethylene (LLDPE) blends with and without compatibilizers base on maleic anhydride grafted HDPE (MAH-g-HDPE) and ethylene-methacrylic acid neutralized sodium metal (Na-EMAA) were prepared by a twin-screw extruder. The blended samples with different ratios of polymers and compatibilizers were characterized on mechanical and rheological properties. Moreover, the phase morphology and dispersion size were studied by using SEM to give better understanding of the compatibility of the blends.
Blends of polyamide-6 (PA-6) and high-density polyethylene (HDPE) with blend ratios of 80/20 (wt/... more Blends of polyamide-6 (PA-6) and high-density polyethylene (HDPE) with blend ratios of 80/20 (wt/wt) and 20/80 (wt/wt) were studied using zinc-neutralized maleic anhydride (MAH) grafted HDPE as compatibilizers. MAH groups were hydrolyzed and neutralized with different amounts of zinc acetate dihydrate in a twin-screw extruder to produce different levels of zinc-neutralization (0, 14, 41, 69, and 95 %) at one and ten parts per hundred of resin of compatibilizer. Melt neutralization of MAH was confirmed by X-ray fluorescence, FT–IR, and rheological properties. SEM micrographs showed a large reduction in the dispersed phase size in the compatibilized blends. Tensile measurements showed improvement of tensile strength for all compatibilized blends; moreover, the elongation at break of compatibilized blends at 10 phr of compatibilizer was improved. Blending increased the crystallization temperature for the PA-6, and the addition of compatibilizer reduced the crystallization temperature slightly. A significant increase in melt viscosity of the compatibilizer was found with zinc addition and adding compatibilizer increased the viscosity of the blends. However, the addition of zinc to the compatibilizer did not change the viscosity in the PA-6-rich blends and actually led to a decrease in viscosity in the HDPE-rich blends.
An ethylene–methacrylic acid copolymer partially neutralized with sodium (Na-EMAA) was successful... more An ethylene–methacrylic acid copolymer partially neutralized with sodium (Na-EMAA) was successfully used to compatibilize Nylon 6 (Ny6) and low-density polyethylene (LDPE) blends. The phase morphology and thermal behavior of these blends were investigated over a range of compositions using a variety of analytical techniques. The addition of small amounts (0.5 phr) of Na-EMAA improved the compatibility of Ny6/LDPE blends as
... τactual = ) (2 nR L PR + Δ = ) /(2nRL P + Δ (3) where n is a multiplication factor according ... more ... τactual = ) (2 nR L PR + Δ = ) /(2nRL P + Δ (3) where n is a multiplication factor according to theBagley correction; and the actual shear rate γactual is defined as actual . ... Sci. 60:1736 5. Sinthavathavorn W, Nithanakul M , Magaraphan R, Grady BP (2007) J. Appl.Polym. Sci. ...
... Plast Polym 41:39–43 4. Bagley EB (1961) The separation of elastic and viscous effects in pol... more ... Plast Polym 41:39–43 4. Bagley EB (1961) The separation of elastic and viscous effects in polymer flow. ... Sinthavathavorn W, Nithitanakul M, Magaraphan R, Grady BP (2008) Blends of polyamide 6 with low-density polyethylene compatibilized with ethylenemethacrylic acid ...
Poly(D,L-lactide-co-glycolide) (PLGA) with encapsulated hydrophobic magnetite (Fe3O4) nanoparticl... more Poly(D,L-lactide-co-glycolide) (PLGA) with encapsulated hydrophobic magnetite (Fe3O4) nanoparticles or hydroxyapatite (HAp) nanoparticles were prepared by the w/o/w emulsion technique. The weight ratios of nanoparticles (Fe3O4 or HAp) to PLGA and polymer molecular weight were varied in the oil phase and the properties of the composite nanoparticles were studied. The final weight percent of nanoparticles in the spherical PLGA particles varied from ~ 5 to 60 wt%. Hydrodynamic diameters of the composite nanoparticles as measured by dynamic light scattering (DLS) were found to decrease with decreasing polymer molecular weight and were independent of nanoparticle loading. Particle sizes measured from TEM were smaller by almost a factor of two vs. those obtained from DLS. The zeta potentials of the particles were about − 23 mV, independent of polymer molecular weight and nanoparticle loading within statistical significance. In vitro cytotoxicity tests show a high level of cytocompatibility suggesting satisfactory biocompatibility for biomedical applications.
Langmuir : the ACS journal of surfaces and colloids, Jan 16, 2014
Hydroxyl groups on the surface of metal oxide nanoparticles (nps) can be protonated or deprotonat... more Hydroxyl groups on the surface of metal oxide nanoparticles (nps) can be protonated or deprotonated depending on solution pH, changing both the magnitude and sign of the nps' surface charge. Binary mixtures of fumed metal oxide nps, dispersed in water at a solution pH where one species is positively charged and the other is negatively charged, form pseudosolid gels at volume fractions as low as 1.5 vol %. This work maps out regions of gel formation for binary mixtures of silica and alumina nps, silica and titania nps, and alumina and titania nps. The microscopic structure of these gels is investigated using transmission electron microscopy (TEM), small-angle x-ray scattering (SAXS), acoustic spectroscopy, and light microscopy.
The effect of simultaneous alignment of polyethylene (PE) lamellae and graphene nanoplatelets (Gn... more The effect of simultaneous alignment of polyethylene (PE) lamellae and graphene nanoplatelets (GnP) on the thermal conductivity (k) of PE-GnP composites is investigated. Measurements reveal a large increase of 1100% in k of the aligned PE-GnP composite using 10 wt% GnPs relative to unoriented pure PE. The rate of increase of k with applied strain for the pure PE-GnP composite with 10 wt% GnP is found to be almost a factor of two higher than the pure PE sample, pointing to the beneficial effect of GnP alignment on k enhancement. Aligned GnPs are further found to be 3 times as effective in enhancing k as in the randomly oriented configuration. Enhancement in k is correlated with the alignment of PE lamellae and GnPs through wide-angle X-ray scattering and polarized Raman spectroscopy. At the maximum applied strain of 400% and using 10 wt% GnPs, a composite k of 5.9 W mK(-1) is achieved. These results demonstrate the great potential of simultaneous alignment effects in achieving high k...
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