New insights into the mixing process.The concept of using highly dispersible silica silica or silicon dioxide, chemical compound, SiO2. It is insoluble in water, slightly soluble in alkalies, and soluble in dilute hydrofluoric acid. Pure silica is colorless to white. as the sole reinforcing filler fill·er 1n. One that fills, as: a. Something added to augment weight or size or fill space. b. A composition, especially a semisolid that hardens on drying, used to fill pores, cracks, or holes in wood, plaster, , together with a silane silane or silicon hydride Any of a series of inorganic compounds of silicon and hydrogen with covalent bonds and the general chemical formula SinH(2n + 2). coupling agent, for the tread tread injury to the coronet of the horse's hoof by treading on it by the opposite hoof, or by another horse when they are being worked in a team. If the coronary matrix is injured there may be a subsequent crack or deformity. compounds of low rolling resistance Rolling resistance, sometimes called rolling friction or rolling drag, is the resistance that occurs when an object such as a ball or tire rolls. It is caused by the deformation of the wheel or tire or the deformation of the ground. tires was first patented (ref. 1) in 1991. Since then, it has become well established. These compounds have a number of problems associated with them: * Energy intensive, multiple-stage mixing cycles are required to achieve processable compound. * Close time and temperature control are required during mixing to achieve silica to silane coupling and to avoid silane degradation DEGRADATION, punishment, ecclesiastical law. A censure by which a clergy man is deprived of his holy orders, which he had as a priest or deacon. (refs. 2 and 3). * The compounds tend to have high viscosities that become even higher with time leading to difficult processing. * The compounds tend to have short scorch times. * The silica to silane coupling reaction A coupling reaction or oxidative coupling in organic chemistry is a catch-all for a range of reactions in Organometallic chemistry where two hydrocarbon radicals are coupled with the aid of a metal containing catalyst. is believed to be hindered by a number of normal compound additives (ref. 4), some of which might be used to improve mixing or process-ability. While investigating this possible hindering hin·der 1 v. hin·dered, hin·der·ing, hin·ders v.tr. 1. To be or get in the way of. 2. To obstruct or delay the progress of. v.intr. of the silica to silane coupling reaction by an aliphatic aliphatic /al·i·phat·ic/ (al?i-fat´ik) pertaining to any member of one of the two major groups of organic compounds, those with a straight or branched chain structure. al·i·phat·ic adj. zinc zinc, metallic chemical element; symbol Zn; at. no. 30; at. wt. 65.38; m.p. 419.58°C;; b.p. 907°C;; sp. gr. 7.133 at 25°C;; valence +2. Zinc is a lustrous bluish-white metal. It is found in Group 12 of the periodic table. soap, we discovered some aspects of the mixing process that we believe have not been reported before. In addition, we have, in collaboration Working together on a project. See collaborative software. with Alpha Technologies, shown that viscoelastic Adj. 1. viscoelastic - having viscous as well as elastic properties natural philosophy, physics - the science of matter and energy and their interactions; "his favorite subject was physics" testing of the uncured compounds can yield useful information regarding filler dispersion dispersion, in chemistry dispersion, in chemistry, mixture in which fine particles of one substance are scattered throughout another substance. A dispersion is classed as a suspension, colloid, or solution. , silica to silane coupling and silane degradation. Experimental Compounds The compounds are shown in table 1. Compound 1 is a control based on the formulation formulation /for·mu·la·tion/ (for?mu-la´shun) the act or product of formulating. American Law Institute Formulation in the published patent for energy efficient tread compounds. Compounds 2 and 3 have the stearic acid stearic acid /ste·a·ric ac·id/ (ste-ar´ik) a saturated 18-carbon fatty acid occurring in most fats and oils, particularly of tropical plants and land animals; used pharmaceutically as a tablet and capsule lubricant and as an emulsifying replaced by an aliphatic zinc soap (Struktol A50P). In compound 2, the zinc soap was added during masterbatch mixing and in compound 3, it was added during the remill stage. Compounds 4 and 5 are the same as the control but the level of stearic acid is increased.
Table 1 - compounds
1 2 3 4 5
Control Zn soap Zn soap 2 phr 3 phr
phr phr phr phr phr
Buna VSL 4020-1 103.0 103.0 103.0 103.0 103.0
Buna CB 10 25.0 25.0 25.0 25.0 25.0
Ultrasil 3370 GR 80.0 80.0 80.0 80.0 80.0
Silane X50S 12.5 12.5 12.5 12.5 12.5
HA oil 5.0 5.0 5.0 5.0 5.0
Zinc oxide 2.5 2.5 2.5 2.5 2.5
Stearic acid 1.0 - - 2.0 3.0
Aliphatic zinc soap - 4.0 4.0 - -
6ppd 2.0 2.0 2.0 2.0 2.0
Wax 1.50 1.50 1.50 1.50 1.50
Sulfur 1.40 1.40 1.40 1.40 1.40
CBS 1.70 1.70 1.70 1.70 1.70
DPG 2.00 2.00 2.00 2.00 2.00
Mixing All the compounds were mixed in a Werner Werner is a name of Germanic origins that could refer to numerous people or entities.
The oldest known usage of the name was in the Habsburg family.
The batches were left to stand at room temperature for one day between each mixing stage. Stage 1 Compounds 1, 2 and 3 were mixed using cycles controlled by time. Both indicated temperature and energy input were continuously measured. The mixing cycles are shown in tables 2, 3 and 4.
Table 2 - masterbatch mix cycle
Time, min Operation
0 Add polymers plus silane
1/2 Add zinc oxide, 3/4 silica and stearic acid or
zinc soap (if used)
3 1/2 Add rest of silica, oil, 6 ppd and wax
4 Sweep down
4 1/2 Dump
Rotor speed: 65 rpm, start and circulating cir·cu·late v. cir·cu·lat·ed, cir·cu·lat·ing, cir·cu·lates v.intr. 1. To move in or flow through a circle or circuit: blood circulating through the body. 2. water temperature: 65 [degrees] C
Table 3 - remill mix cycle
Time, min. Operation
0 Add masterbatch and zinc soap (if used)
3 1/2 Dump
Rotor speed: 65 rpm, start and circulating water temperature: 65 [degrees] C
Table 4 - final mix cycle
Time, min. Operation
0 Add remill masterbatch plus curatives
1 max. Dump at max. 105 [degrees] C or after one minute
Rotor speed: 65 rpm, start and circulating water temperature: 50 [degrees] C Stage 2 Compounds 1,4 and 5 were mixed also using the same time controlled mixing procedures as shown in tables 2, 3 and 4. Stage 3 Compound 1 was mixed four times, mixes 1 to 4, this time using mixing cycles controlled by energy input. Both time and indicated temperature were continuously measured. The mixing cycles are shown in tables 5 to 9.
Table 5 - masterbatch mix cycle for mixes 1 to 3
Time, Operation Energy,
min. W. hours
0 Add polymers 0
1/2 Add zinc oxide, 3/4 silica, 3/4 silane and 50?
stearic acid
? Add rest of silica, rest of silane, oil, 6 ppd 550
and wax
? Sweep down 700
? Dump at 750 W. hours. 750
Rotor speed: mix 1, 65 rpm; mix 2, 55 rpm; mix 3, 45 rpm. Start and circulating water temperature: 65 [degrees] C
Table 6 - masterbatch mix cycle for mix 4
Time, Operation Energy,
min. W. hours
0 Add polymers 0
1/2 Add zinc oxide, 3/4 silica, 314 silane and 50?
stearic acid
? Add mst of silica, mst of silane, oil, 6 ppd 300
and wax
? Rotor speed from 65 rpm to 45 rpm 600
? Sweep down 750
? Dump at 750 W. hours 800
Rotor speed: 65/45 rpm, start and circulating water temperature: 65 [degrees] C Table 7 - remill mix cycle for mixes 1 to 3 Time, Operation Energy, min W. hours 0 Add masterbatch 0 ? Dump at 650 W. hours 650 Rotor speed: mix 1,65 rpm; mix 2, 55 rpm; mix 3, 45 rpm. Start and circulating water temperature: 65 [degrees] C Table 8 - remill mix cycle for mixes 4 Time, Operation Energy, min. W. hours 0 Add masterbatch 0 ? Rotor speed from 65 rpm to 45 rpm 400 ? Dump at 750 W. hours 750 Rotor speed: 65/45 rpm, start and circulating water temperature: 65 [degrees] C Table 9 - final mix cycle for mixes 1 to 4 Time, Operation min. 0 Add remilled masterbatch plus curatives 1 max. Dump at max. 105 [degrees] C or after one minute Rotor speed: 65 rpm, start and circulating water temperature: 50 [degrees] C Stage 4 Compound 1 was mixed four more times, mixes 5 to 8, again using mixing cycles controlled by energy input, but with the total energy input increased by about 25%. Both time and indicated temperature were continuously measured. The mixing cycles are shown in tables 10 to 14.
Table 10 - masterbatch mix cycle for mixes 5 to 7
Time, Operation Energy,
min. W. hours
0 Add polymers 0
1/2 Add zinc oxide, 3/4 silica, 3/4 silane and 50?
stearic acid
? Add rest of silica, rest of silane, oil, 6 ppd 300
and wax
? Sweep down 750
? Dump at 1,000 W. hours 1,000
Rotor speed: mix 5, 65 rpm; mix 6, 55 rpm; mix 7, 45 rpm. Start and circulating water temperature: 65 [degrees] C
Table 11 - masterbatch mix cycle for mix 8
Time, Operation Energy,
min. W. hours
0 Add polymers 0
1/2 Add zinc oxide, 3/4 silica, 3/4 silane and 50?
stearic acid
? Add rest of silica, rest of silane, oil, 6 ppd 300
and wax
? Rotor speed from 65 rpm to 45 rpm 600
? Sweep down 750
? Dump at 1,000 W. hours. 1,000
Rotor speed: 65/45 rpm, start and circulating water temperature: 65 [degrees] C Table 12 - remill mix cycle for mix 5 to 7 Time, Operation Energy, min. W. hours 0 Add masterbatch 0 ? Dump at 750 W. hours 750 Rotor speed: mix 5, 65 rpm, mix 6, 55 rpm, mix 7, 45 rpm. Start and circulating water temperature: 65 [degrees] C Table 13 - remill mix cycle for mix 8 Time, Operation Energy, min. W. hours 0 Add masterbatch 0 ? Rotor speed from 65 rpm to 45 rpm 400 ? Dump at 750 W. hours 750 Rotor speed: 65/45 rpm, start and circulating water temperature: 65 [degrees] C Table 14 - final mix cycle for mix 5 to 8 Time, Operation min. 0 Add remilled masterbatch plus curatives 1 max. Dump at max 105 [degrees] C or after one minute Rotor speed: 65 rpm, start and circulating water temperature: 65 [degrees] C Testing Viscosity and scorch were measured using a Mooney Mooney is family name, which is probably predominantly derived from the Irish Ó Maonaigh. It can also be spelled Moony, Meaney, Mauney, Moon, Money. The word can refer to: Companies
Meaney spelling Instrument for measuring the viscosity (resistance to internal flow) of a fluid. In one type, the time taken for a given volume of fluid to flow through an opening is recorded. . Curing characteristics were measured using an MDR MDR, n See multidrug resistance. MDR, n the abbreviation for minimum daily requirement, specifically the Minimum Daily Requirements for Specific Nutrients compiled by the United States Food and Drug Administration. Rheometer rhe·om·e·ter n. An instrument for measuring the flow of viscous liquids, such as blood. 2000. Both instruments are from Alpha Technologies. Viscoelastic properties of the uncured compounds were measured using a rubber process analyzer analyzer /ana·ly·zer/ (an´ah-li?zer) 1. a Nicol prism attached to a polarizing apparatus which extinguishes the ray of light polarized by the polarizer. 2. (RPA RPA Remote Patron Authentication RPA Rural Payments Agency (UK Department of Environment, Food and Rural Affairs) RPA Replication Protein A RPA RNAse Protection Assay RPA Regional Plan Association RPA Random-Phase Approximation 2000) by Alpha Technologies. Garvey Gar·vey , Marcus (Moziah) Aurelius 1887-1940. Jamaican Black nationalist active in America in the 1920s. He founded the Universal Negro Improvement Association (1914) and later urged African Americans to establish an independent country in Africa. die extrusion trials were made using a Troester GS 30/K10D 30 mm diameter cold feed extruder, run at 70 rpm. This extruder has an L/D L/D Labor and Delivery L/D Lethal Dose L/D Lift/Drag (ratio) L/D Low Dynamic L/D Limiter/Discriminator L/D Loading / Discharging Rate (shipping) ratio of 10:1. Cured physical properties were measured on samples cured to [t'.sub.c](100) at 160 [degrees] C using an Instron tensometer A tensometer is a device used to evaluate the Young's modulus (how much it stretches under strain) of a material. The tensometer is usually loaded with a sample between two grips that are adjusted manually to apply force to the specimen. . Dynamic heat build-up build·up also build-up n. 1. The act or process of amassing or increasing: a military buildup; a buildup of tension during the strike. 2. was measured on samples cured to [t'.sub.c](100) at 160 [degrees] C using a Doli DOLI Date Of Last Inventory Goodrich Goodrich is a surname, and may refer to:
Viscoelastic properties on samples cured to [t'.sub.c](100) at 160 [degrees] C were measured using an MTS (1) See Microsoft Transaction Server. (2) (Modular TV System) The stereo channel added to the NTSC standard, which includes the SAP audio channel for special use. 1. MTS - Message Transport System. 2. 831.50 servohydraulic tester. Viscoelastic properties were measured in shear shear: see strength of materials. Shear A straining action wherein applied forces produce a sliding or skewing type of deformation. at a frequency of 10 Hz at 20 [degrees] C, using discs nominally 20 mm in diameter and 3 mm thick. The shear was made in the direction of material flow during processing. The tests were displacement displacement, in psychology: see defense mechanism. Same as offset. See base/displacement. sweeps of 17 to 20 points logarithmically log·a·rithm n. Mathematics The power to which a base, such as 10, must be raised to produce a given number. If nx = a, the logarithm of a, with n as the base, is x; symbolically, logn a = x. arranged from about 0.5% DSA (1) (Directory Server Agent) An X.500 program that looks up the address of a recipient in a Directory Information Base (DIB), also known as white pages. It accepts requests from the Directory User Agent (DUA) counterpart in the workstation. to 20% DSA. They were conducted in duplicate DUPLICATE. The double of anything. 2. It is usually applied to agreements, letters, receipts, and the like, when two originals are made of either of them. Each copy has the same effect. and repeat tests carded out when differences of primary properties greater than 5% were encountered. Results The masterbatch mixing energy versus time graphs for the stage 1 compounds are shown in figure 1. At this masterbatch stage, the compound labeled zinc soap in the remill has neither stearic acid nor zinc soap in it. The difference between the curve for this compound and the other two is clear. Without either stearic acid or the zinc soap, the mixing energy falls off sharply after the first power peak. This indicates that the mix is having difficulty in maintaining a cohesive cohesive, n the capability to cohere or stick together to form a mass. mass and in achieving effective filler incorporation. When the final addition of filler is made, the compound without either stearic acid or the zinc soap does not even show a clear first power peak. It is also interesting to note that none of the compounds exhibits a second power peak (indication of full wetting out of the filler by the polymer) during masterbatch mixing. Despite a diligent dil·i·gent adj. Marked by persevering, painstaking effort. See Synonyms at busy. [Middle English, from Old French, from Latin d search of the literature, we have been unable to find any reference to this strong effect of stearic acid on the mixing of silica reinforced compounds, nor to the absence of a second power peak when mixing the masterbatch of silica filled compounds. The remill mixing energy versus time graphs for the stage 1 compounds are shown in figure 2. These curves clearly show that the second power peak for these silica reinforced compounds occurs during the early part of the remill. The most pronounced second power peak is shown by the compound having the zinc soap added during the remill. The curve for this mix then goes on to exhibit a steeper slope for the dispersive dispersive /dis·per·sive/ (-per´siv) 1. tending to become dispersed. 2. promoting dispersion. mixing region after the second power peak. This improved mixing behavior during the remill stage should help to offset the poor mixing behavior this compound showed during its masterbatch stage. [Figure 2 ILLUSTRATION OMITTED] The integrated mixing energy data and the compound dump temperatures, measured with a needle pyrometer immediately after dumping, for these compounds are shown in table 15. The integrated mixing energy data could have easily been misinterpreted had the energy versus time graphs not been taken into consideration. Because of the low energy input after the first power peak of the masterbatch and the sharp fall off of the energy input during the dispersive mixing section of the remill, for the compound with the zinc soap added in the remill, this compound requires the least total energy to mix.
Table 15 - stage 1 mixing data
1 2 3
Control Zn soap Zn soap
phr in M/B in remill
phr phr
Stearic acid 1.0 - -
Aliphatic zinc soap - 4.0 4.0
Mixing energy
Masterbatch, GJ/[m.sup.3] 1.940 1.783 1.552
Remill, GJ/[m.sup.3] 2.180 2.042 1.980
Final mix, GJ/[m.sup.3] 0.666 0.592 0.584
Total, GJ/[m.sup.3] 4.641 4.281 3.984
Needle pyrometer dump temperature
Masterbatch, [degrees] C 161 165 151
Remill, [degrees] C 183 189 184
Final mix, [degrees] C 135 141 139
The dump temperatures for the remill and final mix are rather higher than would normally be used in production, but they do not appear to have adversely affected the compound properties. This is shown by the Mooney viscosities, the Mooney scorch times and the extrusion data, shown in table 16, and the rheometer cure curves, shown in figure 3. [Figure 3 ILLUSTRATION OMITTED] The rheometer cure curves for both compounds containing the zinc soap exhibit much lower torque development than the compound containing stearic acid. At first we believed this was due to die slippage Slippage The difference between estimated transaction costs and the amount actually paid. Notes: Slippage is usually attributed to a change in the spread. See also: Spread, Transaction Costs Slippage caused by surface lubrication lubrication, introduction of a substance between the contact surfaces of moving parts to reduce friction and to dissipate heat. A lubricant may be oil, grease, graphite, or any substance—gas, liquid, semisolid, or solid—that permits free action of from the soap. However, we were able to show that this was not the case. Rheometer cure curves were run, using the RPA 2000, with different angles of oscillation Oscillation Any effect that varies in a back-and-forth or reciprocating manner. Examples of oscillation include the variations of pressure in a sound wave and the fluctuations in a mathematical function whose value repeatedly alternates above and below some , from very low strain to very high strain. While the actual torque values varied, the torque development for the compounds containing the soap relative to that for the compound containing stearic acid remained the same. It must be remembered that the rheometer measures the viscoelastic property, elastic elastic Of or relating to the demand for a good or service when the quantity purchased varies significantly in response to price changes in the good or service. torque. This will only be proportional proportional values expressed as a proportion of the total number of values in a series. proportional dwarf the patient is a miniature without disproportionate reductions or enlargements of body parts. to crosslink density if all other aspects of the compound are equal. If there are differences in the type or loading of filler or the dispersion of the same filler, then this property will be affected. We believe that the lower rheometer torque values given by both the compounds containing the zinc soap indicate superior filler dispersion. The beneficial influence of the zinc soap on filler dispersion and on both Mooney viscosity and Mooney scorch time is also clearly shown and is independent of the addition point. From the extrusion trial data of these compounds, shown in table 16, both compounds containing the zinc soap show a higher output rate and reduced back pressure. Again, the effect of the soap is independent of its point of addition.
Table 16 - stage 1 compound processability data
1 2 3
Control Zn soap Zn soap
phr in M/B in remill
phr phr
Stearic acid 1.0 - -
Aliphatic zinc soap - 4.0 4.0
Mooney viscosity at 100 [degrees] C
Masterbatch, MS 1+4 74 83 84
Remill, MS 1+4 76 84 72
Final mix, MS 1+4 57 52 48
Final mix, ML 1+4 104.3 87.4 81.3
Mooney scorch at 135 [degrees] C
[t.sub.5], min. 6.6 14.1 13.9
Garvey die extrusion, screw speed 70 rpm
Extrusion rate, g/min. 204 227 228
Extrusion pressure, bar 76 53 49
The cured modulus See modulo. data, shown in table 17, shows that the compounds containing the zinc soap have slightly lower modulus values than the compound containing stearic acid. However, the ratio of M300 to M100, which is sometimes used as an indication of the strength of the silane coupling, is higher for the compounds containing the zinc soap. It is possible that this property is also affected by filler dispersion, as well as by silane coupling.
Table 17 - stage 1 cured modulus and heat build-up
1 2 3
Control Zn soap Zn soap
phr in M/B in remill
phr phr
Stearic acid 1.0 - -
Aliphatic zinc soap - 4.0 4.0
Cured modulus, cure: [t'.sub.c](100) @ 160 [degrees] C
M100, MPa 3.2 2.6 2.8
M200, MPa 8.7 7.6 8.1
M300, MPa 15.8 14.3 15.2
Ratio M300:M100 4.94 5.50 5.43
Goodrich heat build up
Pre-load 1 MPa, stroke 6.35 mm, start temp. 50 [degrees] C,
time 30 min.
HBU, [degrees] C 122.5 128.6 125.3
As mentioned in the introduction, this first stage was intended to investigate the potential for a zinc soap to interfere with the silane coupling reaction. To evaluate this effect, we carded out viscoelastic dynamic tests on cured samples. The curves for elastic and viscous viscous /vis·cous/ (vis´kus) sticky or gummy; having a high degree of viscosity. vis·cous adj. 1. Having relatively high resistance to flow. 2. Viscid. modulus versus strain and tangent tangent, in mathematics. 1 In geometry, the tangent to a circle or sphere is a straight line that intersects the circle or sphere in one and only one point. [Delta] versus energy input are shown in figures 4, 5 and 6. [Figures 4-6 ILLUSTRATION OMITTED] The two compounds containing the zinc soap show very similar properties, regardless of the addition point of the soap. The elastic and viscous moduli In theoretical physics, moduli are scalar fields whose different values are equally good (each one such scalar field is called a modulus). The reason is that the potential energy for moduli is constant, which can be guaranteed, for example, by supersymmetry (with of these compounds are considerably lower than those of the compound containing stearic acid. This is also probably due to improved filler dispersion. The compounds containing the zinc soap also show lower tangent [Delta] values than the compound containing stearic acid, but here the difference is not so large as with the moduli values. The fact that there are practically no differences between the viscoelastic dynamic properties of the compound where the zinc soap was added during masterbatch mixing and the compound where it was added during the remill stage indicates that there is no interference of the silane reaction by the zinc soap. We would not normally recommend this aliphatic zinc soap for silica reinforced compounds, because a zinc and potassium potassium (pətăs`ēəm), a metallic chemical element; symbol K [Lat. kalium=alkali]; at. no. 19; at. wt. 39.0983; m.p. 63.25°C;; b.p. 760°C;; sp. gr. .862 at 20°C;; valence +1. soap that is more polar usually gives better compound processing properties, particularly for extrusion (ref. 5). However, we believe that this more polar soap has a much greater attraction for the silica surface and that it will compete with the silane for the silica surface if it is added during masterbatch mixing. Where processing problems are encountered within the mixing process, it may be necessary to add a process additive additive In foods, any of various chemical substances added to produce desirable effects. Additives include such substances as artificial or natural colourings and flavourings; stabilizers, emulsifiers, and thickeners; preservatives and humectants (moisture-retainers); and during the masterbatch mix cycle, hence the need for this investigation. A further demonstration of the remarkable effect that stearic acid has on the masterbatch mixing of this silica reinforced compound is shown by the mixing energy versus time curves for the stage 2 compounds. These are shown in figure 7. Here, the levels of stearic acid are 1, 2 and 3 phr. The rate of energy rise to the first power peak is strongly affected by the stearic acid level. The mixing cycles were the same as for the previous mixes. There is still no second power peak achieved during masterbatch mixing at any of the levels of stearic acid used. [Figure 7 ILLUSTRATION OMITTED] The mixing energy versus time curves for the remill cycles of these compounds are shown in figure 8. Again, the second power peak occurs during the early part of the remill cycle. As the stearic acid level rises, the second power peak becomes less defined. There were virtually no differences between the total mixing energies, the dump temperatures and the Mooney viscosities of these compounds. [Figure 8 ILLUSTRATION OMITTED] The Mooney viscosities and scorch times, together with some basic data from an extrusion trial, are shown in table 18. The masterbatch viscosities are reduced with increasing stearic acid levels, but the final mixes show little variation with a tendency for higher viscosities at high stearic ste·ar·ic adj. 1. Of, relating to, or similar to stearin or fat. 2. Of or relating to stearic acid. [French stéarique, from Greek stear, tallow; see level. The Mooney scorch values show an increase with stearic acid level.
Table 18 - stage 2 compound processability data
1 2 3
Control Zn soap Zn soap
phr in M/B in remill
phr phr
Stearic acid 1.0 2.0 3.0
Mooney viscosity at 100 [degrees] C
Masterbatch, MS 1+4 95.4 91.2 84.4
Final mix, MS 1+4 51.1 48.8 55.6
Final mix, ML 1+4 93.5 90.9 104.6
Mooney scorch at 135 [degrees] C
[t.sub.5], min. 9.2 12.3
Garvey die extrusion, screw speed 70 rpm
Extrusion rate, g/min 193.5 220.2 214.9
Extrusion pressure, bar 88 69 72
The extrusion trial data, which are comparable with the data shown for the stage 1 compounds, show that increasing the stearic acid level confers some improvement, but it is only about half that given by the zinc soap. All the improvement occurs with the change from 1 phr to 2 phr. No further improvement is given by increasing the stearic acid level to 3 phr. The rheometer cure curves, show that they all reach the same level of torque and show very similar cure rates, but that the cure initiation initiation, the transition and attendant ceremonies, such as ordeals and rites, involved in passing from one state or status to another, often from childhood to adulthood. It was among the most important social institutions of early humans. time increases with stearic acid level. In stage 3, compound 1 was mixed four times using mixing cycles controlled by energy, but with different rotor speeds. Mix 1 at 65 rpm, mix 2 at 55 rpm, mix 3 at 45 rpm and mix 4 were a combination of 65 rpm and 45 rpm. This combination of rotor speeds was used to try to extend the mixing time to allow the silane reaction to proceed further without the temperature rising to a level at which silane degradation might occur. The masterbatch mixing energy versus time graphs for the stage 3 compounds are shown in figure 9. The influence of the reducing rotor speed from mix 1 to mix 3 is clear and as expected, as is the effect of changing the rotor speed from 65 rpm to 45 rpm during the cycle of mix 4. [Figure 9 ILLUSTRATION OMITTED] The indicated temperature versus time curves clearly show that reducing rotor speed reduces the rate of temperature build-up, as expected. It is also shown that changing from 65 rpm to 45 rpm during the cycle effectively halts the temperature rise. For the remill mixing, the energy versus time graphs for these mixes are shown in figure 10 and the indicated temperature versus time graphs are shown in figure 11. The second power peak for all these mixes again occurs during the early part of the remill. The second power peak of the 45 rpm mix is less clearly defined than at the higher rotor speeds. There was also less difference between the energy levels of the mixes at 65 rpm and 55 rpm than there was between those at 55 rpm and 45 rpm. As with the masterbatch mixing, reducing rotor speed reduces the rate of temperature build-up and changing from 65 rpm to 45 rpm during the cycle effectively halts the temperature rise. [Figures 10-11 ILLUSTRATION OMITTED] The integrated mixing energy data and the pyrometer dump temperatures are shown in table 19. As expected, all the compounds have very similar total mix energies because the mixes were controlled by energy. The data show that reducing the rotor speed solves the problem of excessively high dump temperatures, particularly for the remill. The two speed mixing process also gave satisfactory dump temperatures.
Table 19 - stage 3 mixing data
Compound 1 Compound 1
mix 7 mix 2
65 rpm 55 rpm
Mixing energy
Masterbatch, GJ/[m.sup.3] 1.925 1.900
Remill, GJ/[m.sup.3] 1.650 1.660
Final mix, GJ/[m.sup.3] 0.658 0.627
Total, GJ/[m.sup.3] 4.123 4.076
Needle pyrometer dump temperature
Masterbatch, [degrees] C 155 145
Remill, [degrees] C 180 161
Final mix, [degrees] C 136 138
Compound 1 Compound 1
mix 3 mix 4
45 rpm 65/45 rpm
Masterbatch, GJ/[m.sup.3] 1.893 2.043
Remill, GJ/[m.sup.3] 1.650 1.862
Final mix, GJ/[m.sup.3] 0.634 0.592
Total, GJ/[m.sup.3] 4.067 4.373
Masterbatch, [degrees] C 146 145
Remill, [degrees] C 146 160
Final mix, [degrees] C 137 136
The rheometer cure curves for these mixes show that the lowest torque development was given by the mix at 65 rpm and the one mixed at 65/45 rpm. The mix at 55 rpm showed a torque development about 20% higher and the mix at 45 rpm another 20% higher. These results probably indicate that reducing the rotor speed of the mixer has reduced the filler dispersion achieved, even though the mixes were mixed to equal energy input. The mix starting with 65 rpm and changing to 45 rpm appears to have equal dispersion to the mix run completely at 65 rpm. The Mooney viscosities and scorch times of these mixes are shown in table 20. The viscosities do not show big differences, but there is a tendency for the viscosity to fall as the rotor speed during mixing is reduced. The mix with the dual rotor speed gave the lowest viscosity. These results probably indicate that as the temperatures reduce with lower rotor speeds, so less silane degradation occurs. For the dual rotor speed mix, this is complemented by a better filler dispersion. The Mooney scorch values show that the mix carded out at 65 rpm had a scorch time about 20% lower than the other three mixes. This is also indicative of silane degradation having occurred in the mix run at 65 rpm.
Table 20 - stage 3 compound processability data
Compound 1 Compound 1
mix 1 mix 2
65 rpm 55 rpm
Mooney viscosity at 100 [degrees] C
Masterbatch, MS 1+4 89.7 87.8
Remill, MS 1+4 68.7 65.4
Final mix, MS 1+4 51.4 48.4
Final mix, ML 1+4 94.0 90.0
Mooney scorch at 135 [degrees] C
[t.sub.5], min. 7.5 10.6
Compound 1 Compound 1
mix 3 mix 4
45 rpm 65/45 rpm
Masterbatch, MS 1+4 84.6 84.5
Remill, MS 1+4 68.1 60.5
Final mix, MS 1+4 48.0 46.9
Final mix, ML 1+4 89.0 85.8
[t.sub.5], min. 10.3 10.5
The cured moduli values, shown in table 21, show that all the single rotor speed mixes have similar modulus values at all elongations and that these are higher than those of the dual rotor speed mix. However, the ratio of the M300 to the M100 is higher for the dual rotor speed mix.
Table 21 - stage 3 cured modulus
Compound 1 Compound 1 Compound 1 Compound 1
mix 1 mix 2 mix 3 mix 4
65 rpm 55 rpm 45 rpm 65/45 rpm
Cured modulus. Cure: [t'.sub.c] (100) @ 160 [degrees] C
M100, MPa 3.3 3.5 3.7 2.8
M200, MPa 8.7 8.9 9.2 7.1
M300, MPa 15.8 15.9 16.0 14.5
Ratio M300:M100 4.79 4.54 4.32 5.18
Viscoelastic tests were carried out at 100 [degrees] C and 0.1 Hz on uncured samples of these mixes by Alpha Technologies using a rubber process analyzer. Elastic modulus elastic modulus or elastic constant In materials science and physical metallurgy, any of various numbers that quantify the response of a material to elastic or springy deflection. versus strain curves are shown in figure 12. Applying the concept developed by Coran CORAN Communications Oriented Application Analysis and Donnet Donnet was a French car maker founded as Donnet-Zedel in 1924 and continuing in business until 1936. Jerome Donnet had made a large amount of money producing aircraft during World War I and in 1924 bought Automobiles Zedel of Pontarlier, Doubs, France. (ref. 6) to this work, the elastic modulus values at low strain show that the mix run at 65 rpm and the dual speed mix show equal and the best filler dispersion. The work by Coran and Donnet was with carbon black and it can not be certain that the interpretation of the data can be the same with silane treated silica reinforced compounds (ref. 7). Indeed, the lower values of elastic modulus may also indicate better silane coupling. The poorest filler dispersion is shown by the compound run at 45 rpm. [Figure 12 ILLUSTRATION OMITTED] The elastic modulus at high strain should be indicative of silane degradation, but the resolution of this property at high strain is poor. However, if the elastic torque is plotted against strain, the resolution at high strain is improved. Here we can see that the mix run at 65 rpm gave the most silane degradation, followed by the mix run at 55 rpm. The least silane degradation is shown by both the mix run at 45 rpm and the dual rotor speed mix. In stage 4, compound 1 was mixed another four times, again using mixing cycles controlled by energy and with the same rotor speeds as used in stage 3, but with the total energy input increased by 30%. The masterbatch mixing energy versus time graphs for these mixes are shown in figure 13. Even with the total masterbatch energy input increased to 2.5 GJ/[m.sup.3] there was still no second power peak during the masterbatch mixing. The remill mixing energy versus time curves, shown in figure 14, again show the second power peak occurring during the early part of the remill. This would seem to indicate that time is also required for the polymer to fully wet out the surface of the silica filler rather than mixing work alone. [Figures 13-14 ILLUSTRATION OMITTED] Conclusions * Stearic acid has a surprisingly strong influence on the mixing efficiency with silica filler. * An aliphatic zinc soap used in place of stearic acid in a silica reinforced SSBR/BR tire tread compound confers improved processing properties. * The addition of this soap during the masterbatch stage does not appear to adversely affect the silane coupling reaction. * The addition of this soap gives improved filler dispersion. * The second power peak of this silica reinforced compound does not occur during the masterbatch cycle, even when it is considerably extended. * The second power peak of this silica reinforced compound always occurs during the early part of the remill. * Mixing with high rotor speeds gives better filler dispersion, but makes temperature control more difficult. * Reducing the rotor speed for the entire mix cycle results in poor filler dispersion. * Starting both the masterbatch and remill mix cycles with high rotor speeds, then reducing the rotor speed to maintain temperature, gives a good combination of filler dispersion, silane coupling and reduces silane degradation. * Viscoelastic properties carried out on uncured compound can give valuable information on filler dispersion, the silane coupling reaction and silane degradation. References (1.) Patent application EP 0501 227, Michelin Michelin in full Compagnie Générale des Etablissments Michelin Leading French manufacturer of tires and other rubber products. It was founded in 1888 by the Michelin brothers, André (1853–1931) and Édouard (1859–1940), to , R. Rauline, February February: see month. 25, 1991. (2.) Degussa Information for the Rubber Industry. "Compounding of Si69-stocks." Degussa AG. (3.) U. Gorl and A. Hunsche, "Advanced investigation into the silica/silane reaction system," presented at the 150th meeting of the Rubber Division, ACS (Asynchronous Communications Server) See network access server. . Louisville, Kentucky  “Louisville” redirects here. For other uses, see Louisville (disambiguation). . Oct. 8-11, 1996. Paper No. 76. (4.) S. Wolff Wolff , Kaspar Friedrich 1733-1794. German anatomist noted for his pioneering work in embryology. His chief work, Theoria Generationis (1759), refuted the theory of preformation, which held that the embryo is a fully formed miniature adult. , Rubber Chem. Technol. 55,967 (1982). (5.) H. Bartels Bartels may refer to:
Manchester (măn`chəstər, –chĕs'tər), city and metropolitan district (1991 pop. 397,400), NW England, on the Irwell, Medlock, Irk, and Tib rivers. , UK. June June: see month. 17-21, 1996. (6.) A.Y. Coran and J.P. Donnet, Rubber Chem. Technol. 65, 1016(1992). (7.) J.S. Dick and H. Pawlowski, "Applications of the rubber process analyzer in characterizing the effects of silica on uncured and cured compound properties," presented at the meeting of the Rubber Division, ACS, Montreal Montreal (mŏn'trēôl`), Fr. Montréal (môNrāäl`), city (1991 pop. 1,017,666), S Que., Canada, on Montreal island, surrounded by St. Lawrence River and Rivière des Prairies. , Canada Canada (kăn`ədə), independent nation (2001 pop. 30,007,094), 3,851,787 sq mi (9,976,128 sq km), N North America. Canada occupies all of North America N of the United States (and E of Alaska) except for Greenland and the French islands of . May 4-8, 1996. Paper No. 34.3 |
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