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Appendix
Appendix
Appendix
Appendix A
A
A
A
The obtained graphs of viscosity are extrapolated from the data of the rheometer, all graphs and data are shown in this appendix.
Fig.67
First step to evaluate the viscosity of solution is to find the range of shear rate see Fig.67.
0 2.000 4.000 6.000 8.000 10.00 12.00 14.00 shear rate (1/s) 0 0.01000 0.02000 0.03000 0.04000 0.05000 0.06000 0.07000 0.08000 0.09000 0.1000 sh e a r st re ss ( P a )
- 111 - Fig.68
After with the range of shear stress it 's possible to find the viscosity see Fig 68.
Fig.69
The Fig. 88 shows the velocity of the rheometer in rad. It should be almost constant.
0 20.000 40.000 60.000 80.000 100.00 120.00 140.00 time (s) 0 5.000E-3 0.01000 0.01500 0.02000 0.02500 vi sc o s ity ( P a .s ) 0 100.00 200.00 300.00 400.00 500.00 600.00 time (s) 1.000E-4 1.000E-3 0.01000 ve lo ci ty ( ra d /s )
ludox 50% temperature sweep-0016o
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shear stress shear rate viscosity time temperature normal stress
Pa 1/s Pa.s s °C Pa 0.08044 2.485 0.03237 5.736 10 912 0.08142 2.458 0.03312 11.544 10 912 0.08239 7.624 0.01081 17.18 10 919.9 0.08338 8.131 0.01025 22.888 10 896.4 0.08435 7.775 0.01085 28.608 10 896.4 0.08533 7.151 0.01193 34.316 10 896.4 0.08632 7.136 0.0121 40.028 10 904.3 0.08729 8.718 0.01001 45.748 10 896.4 0.08828 9.129 9.67E-03 51.48 10 888.6 0.08917 9.561 9.33E-03 57.192 10 880.7 0.09016 9.514 9.48E-03 62.896 10 880.7 0.09114 9.244 9.86E-03 68.64 10 857.1 0.09211 9.313 9.89E-03 74.332 10 865 0.09309 10.9 8.54E-03 80.064 10 857.1 0.09407 11.7 8.04E-03 85.76 10 841.4 0.09506 11.24 8.45E-03 91.476 10 817.8 0.09603 10.06 9.55E-03 97.2 10 825.7 0.09701 9.719 9.98E-03 102.9 10 802.1 0.09799 11.6 8.45E-03 108.65 10 802.1 0.09897 12.48 7.93E-03 114.34 10 770.6 0.09987 11.98 8.34E-03 120.04 10 747.1
- 113 - Fig.70
This picture shows the newtonian behaviour of the sample.
Fig.71
The fig.71 shows an other method to find the viscosity when there aren't enough information about the solution which is considered. In the bottom of the Appendix A the oscillatory tests is explained.
0 50.00 100.0 150.0 200.0 250.0 300.0 shear rate (1/s) 0 1.000 2.000 3.000 4.000 5.000 6.000 7.000 8.000 sh e a r st re ss ( P a ) 0 100.00 200.00 300.00 400.00 500.00 600.00 time (s) 0.01000 0.1000 1.000 G ' (P a ) 0.01000 0.1000 1.000 G '' ( P a ) 0 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 90.00 d e lt a ( d e g re e s )
ludox 50% temperature sweep-0016o
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shear stress shear rate viscosity time temperature normal stress
Pa 1/s Pa.s s °C Pa 0.4994 6.332 0.07886 2.884 20 598.9 0.9779 17.07 0.05731 5.768 20 598.9 1.453 28.61 0.02508 8.62 20 606.8 1.85 37.8 0.01 11.468 20 606.8 2.327 56.65 0.004107 14.324 20 614.7 2.801 71.27 0.003931 17.188 20 614.7 3.279 84.85 0.003864 20.052 20 630.4 3.755 97.96 0.003833 22.916 20 638.3 4.232 113.1 0.003742 25.76 20 630.4 4.708 126.6 0.003718 28.628 20 638.3 5.184 140.6 0.003687 31.536 20 630.4 5.66 153.8 0.003681 34.328 20 630.4 6.136 167.5 0.003663 37.196 20 630.4 6.612 180.8 0.003656 40.052 20 630.4 7.089 194 0.003655 42.912 20 630.4 7.566 207.6 0.003644 45.772 20 630.4 8.039 221.1 0.003635 48.632 20 630.4 8.516 234.2 0.003636 51.472 20 622.5 8.994 247.7 0.003632 54.388 20 630.4 9.469 261.4 0.003623 57.192 20 630.4 9.945 275 0.003617 60.084 20 638.3
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Introduction to Oscillatory Tests
We learn at an early age that materials may be gases, liquids or solids. But this is an oversimplification. Many industrial materials show behaviour which is neither completely liquid nor completely solid, but is somewhere between the two. Such materials are termed viscoelastic. Typical examples are polymer solutions and melts, and particulate dispersions such as paints, inks, drilling fluids, creams and lotions, and many types of foodstuffs. It is viscoelasticity which is responsible, at least in part, for the handling properties of these materials, and it is important that they should exhibit it in the correct degree. For example if a printing ink is too elastic (solid) it will fail to enter the nip, whereas if it is too liquid it will show poor dot definition. There are several ways of examining the viscoelastic properties of materials, but the commonest, and most versatile, is to use oscillatory rheology. If a sinusoidal stress, σ (force acting over an area), is placed on a solid sample, a sinusoidal displacement (strain, γ) will result which is in phase with the applied stress. The modulus, or stiffness, of the material can be obtained by dividing the amplitude of the stress, σ0, by the amplitude of the strain, γ0 (Figure 72):
Fig.72. Strain Response to a Sinusoidally-Applied Stress for a Solid Material
If a sinusoidal stress is applied to a liquid sample, the stress is in phase with the rate of change of strain, and a phase lag of 90° is therefore introduced between the stress and the strain (Figure 92):
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Fig.73: Strain Response to a Sinusoidally-Applied Stress for a Liquid Material
For viscoelastic materials, the phase angle, δ, will be somewhere between 0° and 90°. The ratio of the stress to the strain amplitude therefore gives the stiffness of the material, and the phase angle describes its viscoelastic nature. The degree to which a material behaves as a solid or liquid depends on the timescale of the observation. Water is usually described as a liquid, of course, but if examined over timescales of less than about a nanosecond, would to be a solid. Ice behaves as a liquid under very high stresses, over periods of years, hence glacier flow. It happens that the materials which are listed above as being viscoelastic show a transition from liquid to solid behaviour over typical laboratory timescales. To examine more precisely the transition time, the frequency, ω, of the applied stress can be varied. The usual method of performing an oscillation experiment is to apply a sinusoidal stress to a sample, over a range of frequencies, and to monitor the strain and phase angle. The stress is kept low so that it can be assumed that the unperturbed properties of the sample are determined. Rather than reporting σ0 / γ0 and phase angle directly, it is more usual to report the storage modulus, G', and loss modulus, G''. These are defined as G' = σ0 cos δ/ γ0 and G'' = σ0 sin δ/ γ0. The advantage of this is that G' represents the “solid” component of the material, and G'' the “liquid” component. The viscosity of a liquid with no solid component would actually be G''/ω.
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Fig.74: Frequency Sweep on Silly Putty at 20°C
Just as polymers show broad transitions in melting point, sometimes over many decades of temperature, so they show transitions over broad frequency ranges. In general, the higher the molecular weight, the broader the range. A material like children’s silly putty shows a range centred
on a frequency of about 10 rads sec-1, equivalent to a time of 0.1 sec. (Figure 75). If examined over
shorter timescales, for example by bouncing, it appears to be a solid. Over longer timescales it flows like a liquid. A deflocculated dispersion shows solid properties at frequencies which depend on the
system, but are typically above about 10 rads sec-1. Flocculated dispersions show transitions at much
lower frequencies, which is why emulsion paints in the can appear as soft solids, but traditional oil paints as stiff liquids. Similarly jam is wobbly and solid-like (low frequency transition), honey is liquid-like (high frequency transition), although they are of similar “stiffness.”
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Appendix B
Appendix B
Appendix B
Appendix B
PRODUCT NAME
LUDOX® AM-30 colloidal silica SYNONYMS
Si-O2, Acticel, "precipitated silica", Aerosil, Hi-Sil, "Perkasil KS 404", "amorphous silica dust", Lo-Vel, Microsil, "fumed silicon dioxide", "silica, amorphous, fumed, non crystalline", Aquafil, Ludox, "Cab-O-Grip II", "Cab-O-Grip II", "Cab-O-Grip II", "Cab-O-Grip II", "Nalcoag 830", Cab-O-Sil, Cab-O-Sil, "Nalcoag 1430", Cab-O-Sperse, Cab-O-Sperse, Santocel, Cataloid, "silica aerogel", "colloidal silica","Aerosil 200", "colloidal silicon dioxide", "silicic anhydride", "Davison SG-67", Silikill, Dicalite, Silcron, "Ent 25, 550", Syloid, Flo-gard, "synthetic silica",
"Silica 100 WQ", "fossil flour", "Silica 300 WQ", 24/R0125, "anti caking agent 551", "highly dispersed SiO2", 24/R1922, "Free flow agent 551", "PPG Silene 732D", SafSil
PRODUCT USE
Synthetic amorphous (non-crystalline) silica (SAS) can be divided into two groups according to whether the manufacturing process is by the wet route (precipitated silica, silica gel) or the thermal route (pyrogenic silica). Colloidal silicas (silica sols) are stable dispersions of SASs in a liquid, usually water. Furthermore, SASs, which are generally hydrophilic, may be rendered hydrophobic by surface treatment. SASs exist as highly pure, white, fluffy powders or milky-white dispersions of these powders in fluids (usually water). A significant proportion of the global production of SAS is rendered hydrophobic by surface modification mainly with Si-organic compounds. Surface modified (after-treated) SAS can be obtained either by physical or chemical reaction. The most common Si-organic compounds used for the treatment are hexamethyldisilazane (CAS No. 999-97-3),
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two give rise to bi-functional units [Si-O-[Si(CH3)2-O]x]. The surface treatment does not change the solid properties e.g. particle size, dissolution kinetics of the inorganic polymer silicon dioxide (silica, SiO2). However, surface treatment does alter physico-chemical properties, e.g. reduced moisture uptake. Thickener, thixotropic and reinforcing agent for inks, resins, rubber, paints and cosmetics. Also used as a matting agent for paints and papers. Base material for high temperature mortars.
