Degradation of dispersant during milling

Chartier, Thierry; Souchard, S.; Baumard, Jean‐François; Vesteghem, H.

doi:10.1016/0955-2219(96)00058-1

Cited by 28 publications

(17 citation statements)

References 4 publications

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“…After 24 h of ball milling, a change of the spectra was observed with the appearance of bands at 1564, 1621, and 1678 cm −1 . These bands may be attributed to amide functions (CO–NH 2 ) 29 . Furthermore, in the spectra of the ball‐milled powder, the peak of the 1710 cm −1 band, which is characteristic of the C=O stretching vibration of the monodentate COOX group, 30 can be seen.…”

Section: Resultsmentioning

confidence: 94%

“…Figure 6 shows FTIR spectra of the powders after ball milling and wet‐jet milling at a range from 1200 to 1800 cm −1 . The bands at 1492 and 1524 cm −1 in the wet‐jet‐milled powder can be assigned to antisymmetrical and symmetrical vibrations of COO − groups 29 in PAA–NH 4 + . After 24 h of ball milling, a change of the spectra was observed with the appearance of bands at 1564, 1621, and 1678 cm −1 .…”

Section: Resultsmentioning

confidence: 99%

“…The IEP value of ball‐milled Al 2 O 3 increases with an increase in the milling time and approaches close to that of native Al 2 O 3 (near 9) (Table II). It is known that the dispersant adsorbed on the Al 2 O 3 particles degrades during ball milling and the IEP value shifts to the basic side after ball milling 29 . This indicates that the dispersant is degraded by the ball milling and the amount of dispersant adsorbed on the Al 2 O 3 particles decreases.…”

Section: Discussionmentioning

confidence: 99%

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State of the Dispersant and Particle Surface During Wet‐Jet Milling for Preparation of a Stable Slurry

Hotta

Yılmaz

Shirai

et al. 2008

Journal of the American Ceramic Society

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Wet‐jet‐milled alumina slurries exhibited distinctly different stability behavior compared with ball‐milled ones in terms of reflocculent efficiency and rheological properties. The distinction was attributed to the different behavior of the same dispersant (NH4+ salt of poly(acrylic acid); PAA–NH4+) in ball milling and wet‐jet milling. Alumina particles after the wet‐jet milling retained the initial surface conditions, although ball‐milled alumina particles yielded more hydroxyl groups on the surface. Furthermore, degradation of dispersant on milling was investigated qualitatively. Infra‐red analysis and isoelectric point measurements suggested that degradation of the dispersant occurred during ball milling, indicating neutralization of the dispersant due to formation of monodentate COOX groups. On the other hand, in the case of wet‐jet milling, COO− groups of PAA–NH4+ were not degraded at all, indicating maintenance of the structures of dispersant with electrostatic repulsion. Change in the polymer size of the dispersant by different milling methods was confirmed using high performance liquid chromatography (HPLC) measurements. The HPLC results of the wet‐jet milled samples showed that a dispersant with a larger molecular size was generated. Force measurement on approach via the colloid probe method in the centrifuged supernatant of the milled slurries confirmed that the interaction distance between an α‐alumina colloid probe and c‐sapphire surface was about two times larger in the wet‐jet‐milled slurry supernatant compared with the ball milled one. Thus, it was found that wet‐jet milling process led to a stable slurry because of the maintenance of not only steric repulsion but also electrostatic repulsion.

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Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

State of the Dispersant and Particle Surface During Wet‐Jet Milling for Preparation of a Stable Slurry

Hotta

Yılmaz

Shirai

et al. 2008

Journal of the American Ceramic Society

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“…It can be observed that the viscosity increased significantly with the time of mixing. If the increase of viscosity during milling were due to a decrease of particle size (increasing of the specific surface area) or to degradation of the dispersant, 33 a higher amount of dispersant would be necessary. Therefore, after each mixing time more dispersant was added.…”

Section: Mixing Timementioning

confidence: 99%

Hydroxyapatite suspensions as precursors of pieces obtained by gelcasting method

Padilla

Carrodeguas

Vallet‐Regí

2004

Journal of the European Ceramic Society

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The aim of this work was to prepare slurries of hydroxyapatite (OHAp) with a high content of solids, which is necessary for shaping pieces by the gelcasting method. For this purpose different studies were carried out using powders of OHAp calcined at temperatures ranging between 600 and 1200 C and several dispersants. Surface area, porosity and chemical composition of OHAp powders played a fundamental role in the viscosity of slurries. The highest concentration of solid was obtained with OHAp calcined at 1200 C. The best dispersant was selected in a first stage, by electrophoretic measurements and sedimentation studies and, finally, by rheological measurements. The concentration of dispersant which provides the minimum viscosity, depended on the calcination temperature of the OHAp. A great increased of viscosity took place for time of slurries preparation higher than 30 min. Milling of powder for 20 h was necessary to improve the rheological behaviour of the slurries. Finally, ceramic bodies were prepared from fluid slurries containing 60 vol.% of solids and the mechanical properties were evaluated. #

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“…Therefore, for the preparation of suspension and paste with dispersed particles, the agglomerated particles are pulverized by mechanical milling methods such as ball milling [10][11][12], planetary ball milling [13] and beads milling [14] using a milling medium. However, ceramic particles after ball milling have tendency to re-flocculate [15] because active sites such as lattice defects are induced on the surface of particles by the excessive collision energy [16].…”

Section: Introductionmentioning

confidence: 99%

Fluidity of methyl cellulose-contained suspensions and pastes prepared from differently milled Al2O3 powder

Sato

Hotta

Yılmaz

et al. 2009

Journal of Colloid and Interface Science

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Degradation of dispersant during milling

Cited by 28 publications

References 4 publications

State of the Dispersant and Particle Surface During Wet‐Jet Milling for Preparation of a Stable Slurry

State of the Dispersant and Particle Surface During Wet‐Jet Milling for Preparation of a Stable Slurry

Hydroxyapatite suspensions as precursors of pieces obtained by gelcasting method

Fluidity of methyl cellulose-contained suspensions and pastes prepared from differently milled Al2O3 powder

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