(THE INFLUENCE OF CALCIUM CARBONATE MORPHOLOGY …Ground calcium carbonate (GCC) Ground natural...
Transcript of (THE INFLUENCE OF CALCIUM CARBONATE MORPHOLOGY …Ground calcium carbonate (GCC) Ground natural...
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(THE INFLUENCE OFCALCIUM CARBONATE MORPHOLOGY
IN REINFORCEMENT OF THERMOPLASTICS)
(تاثیر مورفولوژی کربنات کلسیم در تقویت ترموپالستیک ها)
(Javad M.Sefidabi, Mohammad S. Yalfani, Maryam Golbaghi)
Presenter: (Maryam Golbaghi)
Paper Code: (imbpa15-00260027)
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Introduction
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Bentonite
Kaolin
Talc
Silica
Mica
CaCO3
Types of Films
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Calcium CarbonateKaolin clay
Silica
Talc Wollastonite Mica
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Talc products are processed using various combinations of
dry grinding, air separation and flotation depending upon the
quality of the crude ore and the properties required for
intended applications.
The talc most often used as filler is commonly called platy
talc. It is distinctly lamellar characteristically soft talc.
Purity is typically >90% and filler grades are 325 mesh and
finer.
Mg3Si4O10(OH)2
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Al2Si2O5(OH)4
Airfloat: Dry-ground, air separated
Water-washed: (disordered metakaolin) Al2Si2O5(OH)4 → Al2Si2O7 + 2 H2O
Delaminated: aluminium-silicon spinel which is sometimes also referred to as a gamma-alumina type
structure: 2 Al2Si2O7 → Si3Al4O12 + SiO2
Calcined: platelet mullite and highly crystalline cristobalite: 3 Si3Al4O12 → 2(3 Al2O3·2 SiO2) + 5 SiO2
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Bentonite is a native colloidal hydrated aluminum silicate or clay found in the midwest
United States, Wyoming, and Canada. Consisting mainly of montmorillonite, a smectite
clay, it is a very fine, odorless, pale buff or cream colored to grayish powder. It consists
of particles in the range of 50 to 150 microns, but also has numerous particles in the 1 to
2 micron range.
The applications of Bentonite:
• Pharmaceutical applications
• As a suspending agent or a viscosity building agent
• As an adsorbent
• As gelling agent
• As emulsion stabilizer
• As clarifying agent
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CaCO3 :
Ground calcium carbonate (GCC)
Precipitated calcium carbonate (PCC)
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Ground calcium carbonate (GCC)
Ground natural carbonates (GCC) are further
characterized as dry-ground products, usually in grades
from 200 mesh to 325 mesh, and wet-ground products.
Of the wet-ground products, fine ground (FG) calcium
carbonates: 3 to 12 micrometers
Ultrafine ground (UFG): 0.7 to 2
Rhombohedral
Prismatic
Aragonitic
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Precipitated calcium carbonate (PCC)
Precipitated calcium carbonate (PCC) is produced for applications requiring any
combination of higher brightnesss, smaller particle size, greater surface area, lower
abrasivity, and higher purity than is generally available from ground natural products.
Fine PCC: 0.7 micrometer
Ultrafine PCC: 0.07 micrometer
Scalenohedral
Spherical
Clustered aragonitic
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Calcite, the most stable form of PCC, has rhombohedra or octahedral structure.
Aragonite and vaterite have an orthorhombic structure that because of its meta-
stability will remain orthorhombic only at temperatures below 400 °C.
High purity limestone (95 % CaCO3) is calcined at 1000 °C in a kiln to produce
carbon dioxide gas and calcium oxide (CaO - lime). The next step is to react the
CaO with water to yield a slurry of Calcium hydroxide (Ca(OH)2 - slake):
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Comparison of calcium carbonates
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Factors affecting on the particle sizes
The carbonation stage (during PCC production)
The pH of aqueous medium
Temperature
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Precipitated calcite particles at different reaction times: (a, d and g)
non-stirred; (b, e and h) mechanically stirred, and (c, f and i)
ultrasounds agitated.
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Research by Agnihotri et al. has shown that particle size is
affected by the CO2 gas flow rate during carbonation.
The particles size is found to decrease with increasing flow
rate.
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The size of the primary particles too decreased with increasing temperature and pH and is the result of the increase in nucleation rate of the primary particles.
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The application of thermoplastics in automotive, aerospace and electronic field has been increasingly
expanded, where the resistance of the products has special importance. High resistant of polymeric
products against impact and scratch is one of the important factors for users.
One of the modifying methods of surface
strength of the polymers is the filler
coating. The reinforcement of polymers is
carried out using surface-coated fillers.
Precipitated Calcium Carbonate (PCC) has
been used as most effective filler to
improve the physical and mechanical
properties of polymers.
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the role of agglomerated particle on stress concentrator can be divided into two parts.
The first is decreasing of stress concentrator points and the second is increasing the
value of stress concentration, i.e., the debonding around a big particle can happen at
lower stress rather than the smaller particles. According to Fig. Calcium Carbonate
with average size of ~ 2.0 µm has a better filler article dispersion and then to form
smaller agglomerates than CaCO3 with 3.0 µm size.
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the role of agglomerated particle on stress concentrator can be divided
into two parts. The first is decreasing of stress concentrator points and the
second is increasing the value of stress concentration, i.e., the debonding
around a big particle can happen at lower stress rather than the smaller
particles. According to Fig. Calcium Carbonate with average size of ~ 2.0
µm has a better filler article dispersion and then to form smaller
agglomerates than CaCO3 with 3.0 µm size.
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It is difficult to distribute Calcium Carbonate
homogeneously in plastic materials since it
has a hydrophilic character. Therefore,
Calcium Carbonate becomes hydrophobic by
coating with compatible and apparent
compound. Calcium Carbonate after surface
coating becomes hydrophobic and compatible
with polymer matrix, and thus mechanical
properties of final product would be
enhanced.
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Differential thermal analytical (DTA) plots and Infrared (IR) spectra were
employed to confirm the stearic acid coating on the Calcium Carbonate surface.
The peaks at 2925 and 2885 cm‒1, are ascribed to the methylene groups of alkyl
chain and the shoulder at 1615 cm‒1 corresponds to the appearance of a
carboxylic group, indicating that stearic acid has been attached to the surface of
CaCO3 .
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Differential thermal analysis (DTA) was employed to explain the mechanism of the physical or chemical
adsorption of stearic acid binding to the surface. Based on Fig. 5, the peaks on DTA curves of samples at
217 °C and 248 °C are attributed to the molecules of stearic acid physically adsorbed in layer of calcite.
The peaks on DTA curves of samples at 342-460 °C are attributed to the molecules of stearic acid
chemically adsorbed in layer of calcite.
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Surface coating of PCC with stearic acid effectively reduces the surface
tension from about 210 to 40-60 mg/m2, which results in a better
dispersion of rigid particles and decreases the adhesion between fillers and
a polymer matrix. From the dissolution curves, where the amount of the
bonded coupling agent is plotted against the quantity used for the
treatment, two characteristic quantities can be determined.
The efficacy of the surface treatment
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If the amount of the coupling agent is increased further, some of it still
can be bonded to the surface, but the dissolved portion increases
drastically. Finally a concentration is reached above which no more coupling
agent can be adsorbed on the surface. The maximum amount of coupling
agent which can bonded to the surface can be determined from the
horizontal part of the dissolution curve and is designated as Cmax--this is
1.95 wt% in case (a).
The efficacy of the surface treatment
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The efficacy of the surface treatment
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The improvement of the coating amount:
In order to improve the toughness of the final polymeric nanocomposites, the
determination of the optimum coating amount of surfactant for PCC fillers is another
critical factor. This depends on the type of surface modification, the chemical reaction, and
the arrangement of the surfactant molecules on the surface.
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IS (J/m)E (MPa)EB (%)σB (MPa)Stearic acid (%)
11.9 ± 0.81673 ± 8014.2 ± 2.628.8 ± 0.6Untreated
12.7 ± 0.91679 ± 5419.1 ± 2.827.3 ± 0.60.3
13.7 ± 0.41717 ± 3718.4 ± 1.528.5 ± 0.40.5
13.1 ± 0.81897 ± 5822.7 ± 2.625.7 ± 0.30.7
13.02 ± 0.91658 ± 7620.9 ± 3.125.8 ± 0.81.0
Mechanical properties of HDPE blend with CaCO3
(3.0 µm) treated with stearic acid
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Mechanical properties of HDPE blend
with CaCO3 (2.0 µm) treated with stearic acid
IS (J/m)E (MPa)EB (%)σB (MPa)Stearic acid (%)
15.7 ± 0.71824 ± 9917.8 ± 2.525.9 ± 1.1Untreated
15.2 ± 0.51872 ± 5817.4 ± 2.127.4 ± 0.40.3
15.6 ± 0.51903 ± 3815.4 ± 1.325.9 ± 0.70.5
16.6 ± 0.82111 ± 10515.4± 2.224.6 ± 1.40.7
16.0 ± 1.01751 ± 7019.6 ± 2.921.5 ± 1.91.0
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The shape of PCC particles can have two
strong effects on the quality of final filler-
polymer compound.
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The shape of particles can ease their dispersion. For example,
needle-like or rod particle may be dispersed better than spherical
ones. Usually spherical particles have higher tendency to
agglomerate than the needle-like or rod ones. Therefore, they resist
against dispersion. In addition, when PCC particles shape with high
dispersion capacity is used for filler-polymer compound production,
lower mechanical energy is consumed through extrusion
Depending on the polymer structure, PCC particles can incorporate
into the matrix when their shape can leave least possible void space
between particles and polymer molecules.
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As it is shown in Fig. (A), PCC in rod form can have high interfacial contact
with linear polyethylene molecules. Spherical particles may create big
distance between groups of polymer molecules leading to empty spaces.
Such void spaces deteriorate the mechanical properties of composite, in
particular impact strength.
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PCC is produced using chemical procedure in which the shape and the size of particles are controlled by the operational parameters. The shape of PCC particles can influence the filler-polymer composite formation. They can ease the dispersion of particles into the matrix of polymer by least resistance against segregation from each other. In addition, particles with appropriate shape have higher resemblance with polymer molecules resulting to minimum void spaces within the matrix of polymer.
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• Boyjoo Y., Pareek V. K., Liu J., J. Mater. Chem. A, 2014, 2, 14270.
• Ciullo P. A., Industrial Minerals and Their Uses, Noyes Publications, 1996, 24.
• Barczewski M., Klozinski A., Jakubowska P., Sterzynski T., J. Appl. Polym. Sci., 2014, 131, 41201.
• Yang K., Yang Q., Li G., Sun Y., Feng D., Polym. Comp. 2006, 443.
• Gendron R., Binet D., J. Vinyl Add. Technol., 1998, 4, 54.
• Bomal Y., Godard P., Polymer Eng. Sci., 1996, 36, 237.
• Bellayer S., Tavard E., Duquesne S., Piechaczyk A., Bourbigot S., Polymer Deg. Stab., 2009, 94, 797.
• Mihajlovic R. S., Vucinic D. R., Sekulic Z. T., Milicevic S. Z., Kolonja B. M. Power Technol. 2013, 245, 208.
• Barhoum A., El-Sheikh S. M., Morsy F., El-Sherbiny S., Reniers F., Dufour T., Delplancke M. P., Van Assche G., Rahier
H., Materials Science and Engineering , 2014, 64, 3.
• Mihajlović, S. R., Vučinić D. R., Sekulić Ž. T., Milićević S. Z., Kolonja B. M. Powder Technology, 2013, 245, 210.
• Gh Fekete, E.; Pukanszky, B.; Toth, A.; Bertoti, I. J. Colloid Interface Sci., 1990, 35, 200.
• Gonzalez J., Albano C., Ichazo M., Diaz B., European Polymer Journal, 2002, 38, 2469.
• Misra R.D.K., Nerikar P., Bertrand K., Murphy D. Materials Science and Engineering A, 2004, 384, 286.
• Mitsuishi K., Ueno S., Kameyama K., Die Angew. Makromol. Chem., 1994, 215, 11.