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Optimizing mixing performance through filler dispersion control.



The fact that good 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.
 is important for the mechanical properties of a rubber compound is indisputable. Dispersion has, in numerous investigations, been shown to correlate to physical properties like tensile strength tensile strength

Ratio of the maximum load a material can support without fracture when being stretched to the original area of a cross section of the material. When stresses less than the tensile strength are removed, a material completely or partially returns to its
 (refs. 1-6), modulus of elasticity modulus of elasticity

The ratio of the stress applied to a body to the strain that results in the body in response to it. The modulus of elasticity of a material is a measure of its stiffness and for most materials remains constant over a range of stress.
 (refs. 7 and 8), tire treadwear (refs. 9 and 10) and dynamic properties (refs. 2, 3 and 11-18).

Recently, with the increasing requirements for reliable processing in the competitive rubber industry, the focus has moved towards the use of dispersion test results to better predict the processing properties of the rubber compound. The aim of this article is to describe a tool for improved mixing and manufacturing economy. The presence of agglomerates with a diameter larger than 40-50 [micro]m may cause detrimental surface defects in manufacturing on a broad scale, ranging from surface flaws to severe processing problems in extrusion. The correlation between dispersion data, the general processing performance in general (refs. 12 and 18) and the rheological rhe·ol·o·gy  
n.
The study of the deformation and flow of matter.



rheo·log
 properties in particular (refs. 5, 19 and 20) are also reported in the literature.

Dispersion test instrument development.

The development of instruments for managing industrial processes, regardless of type, usually passes through three phases:

* Initial laboratory trials;

* a second phase in which the results from continuous and systematic measurements are used to manually adjust manufacturing steps or processes; and

* a final step in which earlier experiences are transformed into algorithms used interactively in an overall managing information system together with the production equipment.

Reliable dispersion testing is particularly important for new rubber materials containing new filler fill·er 1  
n.
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,
 combinations. In such cases there is a need for accurate characterization to speed up test programs by limiting the number of necessary test runs. During years of tests on tires in different environments and testing conditions, matrix methods have been found to work well in predicting the wear resistance of tires. The need for well dispersed dis·perse  
v. dis·persed, dis·pers·ing, dis·pers·es

v.tr.
1.
a. To drive off or scatter in different directions: The police dispersed the crowd.

b.
 rubber has also become more evident for larger manufacturers of other rubber components besides tires, since the performance and processing limits are continuously stretched. This need for fast and reliable testing has generated a number of different types of equipment for optimizing the manufacture of rubber goods. Dispersion test equipment expected to fulfill the requirements indicated may be based on one or a combination of the following: Electrical methods (refs. 11 and 22);

* mechanical methods (refs. 23 and 24);

* transmission- and scanning electron microscopic Adj. 1. electron microscopic - of or relating to or involving an electron microscope  methods (refs. 25-27);

* spectroscopic spec·tro·scope  
n.
An instrument for producing and observing spectra.



spectro·scop
 methods (refs. 25, 28 and 29); and

* optical dispersion test methods (refs. 4, 22, 27 and 30-34).

Among the known dispersion test methods, the latter has attracted a special interest and is more widely used. This is probably due to its close relation with the most common practical way of judging a rubber mix or vulcanizate, to cut a piece of it and simply look at its cross section. It is a quick test for an experienced rubber technician, and requires hardly any technical equipment. Even small differences in the topography topography (təpŏg`rəfē), description or representation of the features and configuration of land surfaces. Topographic maps use symbols and coloring, with particular attention given to the shape and elevations of terrain.  of a surface are recognized without magnification Magnification

A measure of the effectiveness of an optical system in enlarging or reducing an image. For an optical system that forms a real image, such a measure is the lateral magnification m
. The features found to be of interest are difficult to describe and characterize in a mathematical way, it is simply a complex judgement based on pattern recognition by a skilled observer.

The next step in improving the evaluation of the dispersion level is to use a method other than the naked eye. Observing the magnified surface might better distinguish and highlight parts which are characteristic for a certain combination of rubber and filler. A microscope with a camera at a fixed angle of light and fixed magnification (ref. 35) made it possible to evaluate and record the test piece under controlled conditions. It also made direct comparison possible with earlier evaluations, e.g., in house corporate standard pictures.

A large step towards a practical test was taken by Persson, whose pioneering work resulted in the invention of the Split-Field evaluation (ref. 36). His apparatus, figures 1 and 2, utilizing a video or CCD CCD
 in full charge-coupled device

Semiconductor device in which the individual semiconductor components are connected so that the electrical charge at the output of one device provides the input to the next device.
 imaging camera, enables direct comparison between an unknown freshly cut surface and images of cut surfaces representing international or corporate standards which, in turn, represent known variations in dispersion. In this way, immediate and direct comparison is made between the sample surface and the reference picture. The idea has been adopted as an ISO-standard test method (ref. 34).

[Figures 1-2 ILLUSTRATION OMITTED]

The final step in the instrumentation evolution involves transformation into an "operator independent" state which strives to reduce parameters linked to the actions of an operator that might affect the test result. In dispersion measurements utilizing optical test methods, the difficult part is to characterize the test surface. Haralick (ref. 37) claimed that all pictures or images consist of three components to a greater or lesser extent: Spectral, textural and contextural con·tex·ture  
n.
1. The act of weaving or assembling parts into a whole.

2. An arrangement of interconnected parts; a structure.



con·tex
 features. The spectral features describe the differences in the grey-scale, textural features contain information on how parts with different grey levels are distributed on the surface (plane), and con-textural features contain information derived from blocks of discrete data surrounding the area being analyzed. The spectral and (textural) spatial parts were regarded as the most important in describing the surface mathematically.

Several units of test equipment aimed at automatically describing the dispersion level exist today (refs. 4, 24, 38 and 39). Also in this case, optical instruments are in the majority.

We believe that the minimum requirements on a test instrument for automatic classification of filler dispersion are:

* Reproducibility in manufacturing. In order to secure maintenance and compatibility between instrument versions, there must be a continuity in the development done in close cooperation with the instrument manufacturing procedures. It is essential that new versions of the instrument are compatible with earlier versions regarding test results. Therefore, only components which perform according to according to
prep.
1. As stated or indicated by; on the authority of: according to historians.

2. In keeping with: according to instructions.

3.
 initially specified functional requirements See information requirements and functional specification.

(specification) functional requirements - What a system should be able to do, the functions it should perform.
 can be allowed. This will not only reduce maintenance costs, but also the variability in the manufacturing steps which will automatically increase system performance and accuracy.

* A standardized standardized

pertaining to data that have been submitted to standardization procedures.


standardized morbidity rate
see morbidity rate.

standardized mortality rate
see mortality rate.
 calibration calibration /cal·i·bra·tion/ (kal?i-bra´shun) determination of the accuracy of an instrument, usually by measurement of its variation from a standard, to ascertain necessary correction factors.  procedure. The approved level of the test result must be related to some definite standard or standard procedure that easily can be reproduced. In order to independently compare test results, there must be a mutual agreement among the users of a certain test method. The calibration procedure must correct unavoidable deterioration de·te·ri·o·ra·tion
n.
The process or condition of becoming worse.
 of the optical system due to, e.g., contamination and decrease in illumination illumination, in art
illumination, in art, decoration of manuscripts and books with colored, gilded pictures, often referred to as miniatures (see miniature painting); historiated and decorated initials; and ornamental border designs.
, and be fast and simple in order to be performed as intended.

* Repeatability. The measured values must be repeatable so that significant effects are distinguished from effects depending on pure chance. This calls for a method with the lowest possible noise.

* Reproducibility. It must be possible to reproduce the test independently of time, test site, personnel, etc., by following the specified conditions and procedures, as described in the instructions for testing according to the test method.

* Representative sampling area. An optimal test area should be used. The test surface must be large enough to allow the algorithm to process an image that contains enough statistical information for correct processing. The measuring range of the instrument must cover the dispersion levels that are expected for a certain material group at a definite instrument setting, and the same evaluation criteria. If this is not done, the tests will be confusing and not comparable. A large area fulfills the statistical requirements, but the trade off is increased process time and, consequently, increased cost for the test. In addition, large amounts of data are generated which require extra storage capacity. A too small area may cause the algorithm to not distinguish important features from noise, resulting in wrong interpretation. The size of the test area is determined by the magnification. Optical test methods are mostly specified for 30x to 100x magnification. The ASTM ASTM
abbr.
American Society for Testing and Materials
 D2663-88 (ref. 31) Method B as one example, specifies a magnification between 75x and 100x.

* Definite instrument settings. If a test instrument is used only for experimental purposes, the instrument settings must be variable within the range of interest. This is especially important during evaluation and verification of a proposed test method. However, as soon as the test method has been approved, any instrument intended for tests according to that particular test method must, with no exception, follow the technical specifications. If a test is used for quality management, it should not be possible to change instrument settings (unless this is specified in the test method), alter automatic calculation procedures or tamper To meddle, alter, or improperly interfere with something; to make changes or corrupt, as in tampering with the evidence.  with calculated (processed) data. Most of the work in developing tests is to identify and avoid uncontrolled influences mainly due to human actions which, therefore, should be kept at a minimum. One parameter which clearly affects the dispersion rating is the degree of magnification (ref. 40).

Scope of work

The objective of this study was to test the new developments described elsewhere (ref. 39) in full scale trials by an independent rubber manufacturer. It would be of particular interest to find relationships between the measures possible to achieve with the automatic dispersion test system, the mixing quality and the actual results in the final manufacturing of rubber components.

Experimental

The items listed in the previous section represent fundamental requirements when developing a test system for automatic classification of particle dispersion in rubber compounds. The instrument and corresponding dispersion standards used in this test are based on the International Standard ISO (1) See ISO speed.

(2) (International Organization for Standardization, Geneva, Switzerland, www.iso.ch) An organization that sets international standards, founded in 1946. The U.S. member body is ANSI.
 11345. The new instrument series has been subjected to a thorough test program involving inter-laboratory tests and replicated multi-factorial performance tests of repeatability and reproducibility. All test methods have been approved by an independent, accredited accredited

recognition by an appropriate authority that the performance of a particular institution has satisfied a prestated set of criteria.


accredited herds
cattle herds which have achieved a low level of reactors to, e.g.
 research station, the Swedish Institute The Swedish Institute (Svenska Institutet, SI) is a Swedish government agency with the responsibility to spread information about Sweden abroad, to promote Swedish interests, and to organise exchanges with other countries in different areas of public life, in particular in  of Fibre and Polymer Research (IFP (1) (Intelligent Forms Processing) Using advanced techniques to scan documents and determine their data content. See ICR.

(2) (Integer Factorization Problem) The difficulty of finding prime numbers in an encryption key.
) in Gothenburg. The system comprises the instrument, including necessary software for data processing data processing or information processing, operations (e.g., handling, merging, sorting, and computing) performed upon data in accordance with strictly defined procedures, such as recording and summarizing the financial transactions of a , data storage and communication, and five different dispersion standards for the polymer/ filler system to be evaluated.

Instrument for automatic classification of dispersion and large agglomerates

The tests were performed with a DisperGrader Model 1000NT with 100x magnification equipped with dispersion scales according to: The carbon black(x,y)-method; the reinforcing carbon black RCB RCB Robinson College of Business
RCB Reinforced Concrete Box
RCB Right Cornerback (football)
RCB Regional Certifying Body (Australia immigration)
RCB Regular Commissions Board (UK) 
(x,y)-method; the semi-reinforcing carbon black SRCB SRCB Sviluppo Relazioni Commerciali Banche (Italian)
SRCB South of the River Community Band (Eagan, MN)
SRCB Sub Record Control Byte
(x)-method; and the EPDM EPDM Ethylene-Propylene-Diene-Monomer
EPDM Enterprise Product Data Management
EPDM Ethylene Propylene Dimonomer (industrial/commercial piping/plumbing components)
EPDM Engineering Product Data Management
(x)-method. Before and after the test the instrument was calibrated cal·i·brate  
tr.v. cal·i·brat·ed, cal·i·brat·ing, cal·i·brates
1. To check, adjust, or determine by comparison with a standard (the graduations of a quantitative measuring instrument):
 according to the manufacturer's instructions using the 0.6 ISO certified See certification.  standard grey photographic standard specimen. The x- and the y-values represent a dispersion number and a rating of the presence of large agglomerates, respectively.

The x-value is a dispersion number based on a scale graded from 1 (very poor) to 10 (excellent) dispersion. The most used test method is the carbon blacks CB (x)-scale for black rubber in general. The dispersion standards in reduced size can be seen in figure 3. If more accurate measures are needed, the CB(x)-scale is divided into two overlapping scales based on different carbon black types. The reinforcing carbon blacks RCB(x,y)-scale corresponds to the lower, coarser part of the CB(x)-scale and the semi-reinforcing carbon blacks scale which corresponds to the smoother (finer) part of the CB(x)-scale. The EPDM(x)-scale represents a further narrowed scale, based on the SRCB(x)-scale, particularly designed for EPDM-rubbers.

[Figure 3 ILLUSTRATION OMITTED]

The y-value which rates the presence of large agglomerates is also based on a scale of 1 to 10. The y-value is, however, not based on visual comparison against photographic standards, but based on the actual size and number of large agglomerates. A high rating, 10, means that there are no agglomerates present in the tested area that are larger than 25 [micro]m in average diameter.

Test procedure

Specimens were prepared using the specimen sample cutter. An unused part of the cutter blade was used when cutting test pieces from the samples. Prior to tests with a different rubber compound, the instrument aperture An orifice. It often refers to an opening in which light is allowed to pass in optical systems such as cameras and lasers. See f-stop and numerical aperture.  was rinsed with cotton soaked soak  
v. soaked, soak·ing, soaks

v.tr.
1.
a. To make thoroughly wet or saturated by or as if by placing in liquid.

b. To immerse in liquid for a period of time.

2.
 in oil free acetone acetone (ăs`ĭtōn), dimethyl ketone (dīmĕth`əl kē`tōn), or 2-propanone (prō`pənōn), CH3COCH3 . Each reported value is the average of five replicated scans. The test procedure was as follows:

1) A test piece is cut from the sample, placed in front of the instrument aperture and firmly pressed against the same. 2) The appropriate scale is chosen. 3) Focusing. 4) The automatic dispersion classification function is activated. 5) The test is performed by starting the first scanning. 6) The scanning procedure is repeated by repeating item 3 to 6 to achieve five independent measurements. 7) Activate the automatic average calculation. 8) Record the process result. 9) Record the dispersion image.

Data acquisition was performed with an external PC and a special data communication program. Dispersion images were stored and transformed into tagged image file-format (TIF TIF Tagged Image File (file name extension)
TIF Tax Increment Financing
TIF Temporary Internet Files
TIF Transport Innovation Fund (UK)
TIF Telecommunications Infrastructure Fund
) with the same software. The TIF-format allows dispersion images to be inserted in test reports and spread sheets for documentation.

Materials tested

To analyze the efficiency of the dispersion test system, four different rubber materials were tested:

* A 65 Shore A peroxide peroxide (pərŏk`sīd), chemical compound containing two oxygen atoms, each of which is bonded to the other and to a radical or some element other than oxygen; e.g.  cured EPDM compound for extrusion;

* a 62 Shore A sulfur cured NR/IR compound for extrusion;

* a 50 Shore A sulfur cured EPDM injection molding injection molding
n.
A manufacturing process for forming objects, as of plastic or metal, by heating the molding material to a fluid state and injecting it into a mold.
 compound; and

* a second 65 Shore A peroxide cured EPDM compound for extrusion.

The compositions of the tested materials are summarized in tables 1-4. All compounds were mixed in a production mixer mixer, either of two electronic devices in which two or more signals are combined. In the type of mixer used in radio receivers, radar receivers, and similar systems, a signal is translated upward or downward in frequency.  with a net volume of 72 liters and intermeshing rotor rotor: see generator; motor, electric.  system.

Table 1-extrusion compound 65 Shore A
Ingredient             Phr      Note

EPDM                   100
Carbon black           150
Plasticizer             60
Curing system                 Peroxide


Table 2-extrusion compound 62 Shore A
Ingredient             Phr      Note

NR/IR                 100
Carbon black           60
Plasticizer            16
Curing system                  Sulfur


Table 3-injection compound 50 Shore A
Ingredient             Phr      Note

EPDM                   100
Carbon black           140
Plasticizer            100
Curing system                  Sulfur


Table 4-injection molding compound 65 Shore A
Ingredient             Phr      Note

EPDM                   100
Carbon black + clay    160
Plasticizer             60
Curing system                 Peroxide


Tests No. 1 to No. 6 were performed on unvulcanized stock, whereas tests No. 7 to No. 9 were made on material from cured test pieces (buttons) vulcanized vul·ca·nize  
tr.v. vul·ca·nized, vul·ca·niz·ing, vul·ca·niz·es
To improve the strength, resiliency, and freedom from stickiness and odor of (rubber, for example) by combining with sulfur or other additives in the presence of heat
 for six minutes at 177 [degrees] C.

Test No. 1 was made on samples taken directly after the dump of the batch out of the internal mixer and test No. 2 after one pass through the mill gap of 2 mm. The 72" mill was run at 30 m per minute. Tests No. 3 to 6 were made on finely milled rubber stocks.

Fresh cuts were made with an unused part of a razor blade ra·zor·blade also ra·zor blade  
n.
A thin sharp-edged piece of steel that can be fitted into a razor.

razor blade nhoja de afeitar

razor blade 
. All dispersion testing was performed with the light parallel with the direction of the cut. Care was taken in rinsing the specimen stage before a new compound was tested to avoid contamination of even thin layers of foreign substances.

Results

The test results are summarized in tables 5-8 and figures 4-17. As can be seen in table 5, there is a significant difference between the dispersion values of the directly dropped batch compared to the dispersion level after one pass through the mill.

[Figures 4-17 ILLUSTRATION OMITTED]

Table 5-extrusion compound EPDM 65 Shore A
Test no.                               CB(x)-value

   1       Directly dropped              0.1-3.7
   2       One pass through the mill     3.8-4.4


Table 6-extrusion compound NR/IR 62 Shore A
Test no.   Speed         Time      Dump
                                   temp.

   3       High          Medium    High
   4       Low           Long      Low
   5       Low           Medium    Low
   6       Medium        Short     Medium

Test no.   Way of        CB(x)-
           mixing         value

   3       Convent.        7.5
   4       Convent.        7.2
   5       Convent.        7.4
   6       Upside down     7.4


Table 7-injection molding compound EPDM 50 Shore A
Test no.   Speed    Time     CB(x)-value

   7       Low      Long        5.2
   8       Medium   Medium      5.1
   9       Fast     Short       5.3


Table 8-extrusion compound EPDM 65 Shore A
Mixer    Comment                  CB(x)
                                  scale

Old     Conventional,        5.1 [+ or -] 0.2
        long mixing time
Old     Conventional,        5.0 [+ or -] 0.2
        short mixing time
Old     Upside-down,         5.0 [+ or -] 0.2
        short mixing time
Old     Upside-down,         5.2 [+ or -] 0.1
        medium mixing time
New     Conventional,        5.2 [+ or -] 0.1
        medium mixing time

Mixer        EPDM(x)               Maximum
              scale               part size

Old      1.0 [+ or -] 0.5         46 [micro]m
Old      0.7 [+ or -] 0.5         52 [micro]m
Old      0.7 [+ or -] 0.1         52 [micro]m
Old      1.1 [+ or -] 0.1         40 [micro]m
New      1.1 [+ or -] 0.1         37 [micro]m

Mixer         Surface
             quafity

Old            80%
Old            65%
Old            65%
Old            90%
New            100%


In tests No. 3 to No. 6, no significant differences in dispersion numbers could be seen in measured dispersion values.

Regarding the presence of large agglomerates, significant differences can only be seen in analyzing the histograms. This is clearly shown in test No. 3, which showed the best dispersion rating, x-value. However, this batch was subsequently found not to be good enough for processing because some agglomerates caused defects during extrusion. Analyzing the figures 10-13 shows the presence of agglomerates including and larger than an average diameter of 57 microns in test No. 3 - 6. The best particle size distribution The particle size distribution[1] ("PSD") of a powder, or granular material, or particles dispersed in fluid, is a list of values or a mathematical function that defines the relative amounts of particles present, sorted according to size.  is found in test Nos. 6, figures 9 and 13. The latter was mixed in the shortest mixing time, i.e., medium rotor speed and was also rated the best among the trials in the extrusion test. Test Nos. 7-9 contained an injection molding compound (III) with a large sight area in single stage mixing. In this application, the maximum particle size Particle size, also called grain size, refers to the diameter of individual grains of sediment, or the lithified particles in clastic rocks. The term may also be applied to other granular materials.  is one of the most important parameters. Optimizing the mixing process is to produce good dispersion with short mixing times. The results of the test and the parameters varied in the test series are shown in table 7.

Table 8 shows results from a second extrusion compound, where the rubber mixture also was independently evaluated by an experienced rubber technician in extrusion and rated on a scale up to 100% surface quality (excellent) by visual inspection. The evaluation criteria in this case are based on experience and not linked to a specific standard.

Discussion

Rubber manufacturing involves a large number of parameters that affect the end result. Most of these variables are interacting and impossible to separate in normal processing conditions. The only way to find correlations with the end properties is systematic testing in connection with long experience of rubber mixing.

One typical example of this is extrusion. In extrusion, the line speed may range from the order of mm' s per second (e.g. large rubber cross sections like tire: treads) compared with 50 m per minute for a window seal with an intricate cross section. Another related area is injection molding, which usually involves much higher shear rates Shear rate is a measure of the rate of shear deformation:



For the simple shear case, it is just a gradient of velocity in a flowing material.
. These differences in requirements call for different mixing procedures as well as different methods of measuring and controlling the same.

In the case of tire treads, the measure and surface appearance of the extrudate are less critical, since it will be further processed in subsequent operations, compared with the extrudate emerging when processing thin cross-sections. In the latter case, it is not possible to correct the surface finish in the subsequent continuous vulcanization vulcanization (vŭl'kənəzā`shən), treatment of rubber to give it certain qualities, e.g., strength, elasticity, and resistance to solvents, and to render it impervious to moderate heat and cold.  in hot air, salt baths or by microwaves. Furthermore, the physical properties of interest are totally different: Sealing surfaces in static applications do not require the same level of, e.g., tensile strength and tear resistance usually required for good wear resistance which is the case for tire treads.

We decided to perform the investigation in a full scale experiment because the test, after all, is intended to be important for managing the mixing process. Of course there is always the problem of not being capable of controlling separate parameters like in laboratory experiments, but on the other hand, if these parameters can not be individually controlled in production, they are, from the mixing manager's point of view, only of academic interest. Most of the tests were performed on unvulcanized rubber. This is not always possible due to entrapped air which may affect the test result.

In this investigation, we found that when manufacturing rubber materials for extrusion of critical components, the conventional matrix methods do not possess the accuracy needed to distinguish between batches with good process capability and those with poor performance.

If, on the other hand, the simple rule to abandon all batches with agglomerates larger than 40 [micro]m was applied, the prediction of the quality of the final extrudate could be predicted with good accuracy. In figure 17, the maximum average agglomerate agglomerate

Large, coarse, angular rock fragments associated with lava flow that are ejected during explosive volcanic eruptions. Although they may appear to resemble sedimentary conglomerates, agglomerates are igneous rocks that consist almost wholly of angular or rounded
 diameter is plotted against the surface quality, the latter an independent evaluation of the mixing quality in this particular case, made by an experienced manufacturer of extruded profiles. Although the test is subjective, not only the order in which the quality is rated is the same, there also seems to be an almost 100% correlation between the two test methods. This means that the image classification system makes the same judgements, i.e., uses the same evaluation criteria as the experienced rubber technician.

Dispersion testing has for a long time been one part of quality control in tire manufacturing. The dispersion number may be rated according to, e.g., the ISO 11 345 and ASTM D2663 test methods or compared to the tire manufacturer's own standards based on the matrix-method like the ASTM D2663 standard. By matrix-method is meant a method which rates the dispersion (particle distribution) as one dimension and the occurrence of large agglomerates as a second. The filler dispersion is evaluated and characterized in two numbers which also may be weighted together into one single rating. In this case, usually only the end physical properties of the materials are concerned. Examples besides tires are tire tubes, engine mounts and down-hole oil seals oil seal
 or shaft seal

In machines, a device that prevents the passage of fluids along a rotating shaft. Seals are necessary when a shaft extends from a housing (enclosure) containing oil, such as a pump or a gearbox.
. It is a convenient way of testing, since single numbers are produced in a format that allows for simple comparisons with other test data, but also serves as a process parameter in closed-loop process management systems.

In case of, e.g., window seals, or similar products, the interest when judging the mixing quality is focused on the processing performance of the batch. This manufacturing is a highly competitive area involving continuous processes. The start up time until the production runs smoothly for such manufacturing may well be a matter of hours. Each new batch that is entered, if not carefully specified, means a risk in entering a compound with slightly different process properties. The outcome is usually variations in measure or surface appearance of the extrudate.

Doing the right thing from the beginning always pays off. However, what exactly the right thing is varies according to the end application. In this investigation, we have found that it is necessary to treat the evaluation of mixer performance in two categories: The physical properties and the processing properties of the rubber compound. The test instrument used in this investigation allows for this characterization.

Conclusions

By image analysis of a fresh cut rubber surface and a software for classifying agglomerates in number and sizes, it is possible to predict the extrusion performance of a rubber compound. In this investigation, rubber mixes that contained no agglomerates larger than 40 [micro]m in average diameter showed excellent process performance in continuous extrusion of thin cross sections. Mixes with agglomerates larger than 40 [micro]m showed various degrees of surface defects, increasing with agglomerate size and number. The result coincides well with the judgement made by personnel experienced in visual dispersion testing, which makes the automatic dispersion test system an efficient tool for mixing optimization.

References

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(4.) C.P. Ebell and D.A. Hemsley, "A novel optical method for estimating the dispersion of carbon black in rubbers," Rubber Chem. Technol., Vol. 54, pp. 698-717 (1981).

(5.) W.M. Hess, R.A. Swor and E.J. Micek, "The influence of carbon black, mixing and compounding variables on dispersion, "Rubber Chem. Technol., Vol. 57, p. 959-1,000. (1984).

(6.) I. Drogin, "A simple direct method for examining the dispersion of carbon black in rubber, "Rubber Age, June (1958).

(7.) B.R. Richmond, "Carbon black dispersion measurement," paper No. 68 presented at the 143rd Meeting of the Rubber Division, American Chemical Society The American Chemical Society (ACS) is a learned society (professional association) based in the United States that supports scientific inquiry in the field of chemistry. Founded in 1876 at New York University, the ACS currently has over 160,000 members at all degree-levels and in , Anaheim, California “Anaheim” redirects here. For Annaheim, see Annaheim, Saskatchewan.

Anaheim is a city in Orange County, California, located 28 miles southeast of Los Angeles.
, May 6-9 (1993).

(8.) J.J. Jansen and G. Kraus, "New method for estimating dispersibility of carbon black in rubber," Rubber Chem. Technol., Vol 53, pp 48-65. (1980).

(9.) M. Gerspacher and C.P. O'Farrel, "Carbon black, micro-dispersion and treadwear," Rubber and Plastics News, October 25 (1993).

(10.) M. Gerspacher, C.P. O'Farrel and H.H. Yang yang (yang) [Chinese] in Chinese philosophy, the active, positive, masculine principle that is complementary to yin; see yin, under principle. , "Role of carbon black dispersion/distribution on rubber compound properties," paper No. 4B, presented at the International Tire Exposition and Conference, Akron, Ohio Akron is a city in the U.S. state of Ohio and the county seat of Summit County.GR6 The municipality is located in northeastern Ohio on the Cuyahoga River between Cleveland to the north and Canton to the south, approximately 60 miles (96 km) west of  (1996).

(11.) J.L. den Otter and G.A. Gerritse, "Measuring the degree of mixing in rubber compounds," Plastics and Rubber Processing Applications, Vol. 4, p. 63 (1984).

(12.) T.R. Manley and C.W. Evans, "The rubber retraction In the law of Defamation, a formal recanting of the libelous or slanderous material.

Retraction is not a defense to defamation, but under certain circumstances, it is admissible in Mitigation of Damages. Cross-references

Libel and Slander.
 test for the measurement of the dispersion of fillers in rubber," Polymer Communications, Vol. 26, pp. 312-315 (1985).

(13.) L.R. Evans and W.C. Fuhz, "Truck tire 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 with highly-dispersed 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. ," paper no. 15, presented at the 150th Technical Meeting of the Rubber Division, American Chemical Society, Anaheim, California, May 6-9 (1997).

(14.) W.C. Fultz and L.R. Evans, "Tire tread compounds with silica/carbon black blends," paper No. 37, presented at the 150th Technical Meeting of the Rubber Division, American Chemical Society, Anaheim, California, May 6-9 (1997).

(15.) W.H. Waddell, P.A Beauregard and L.R. Evans, "Ultrahigh ul·tra·high  
adj.
Exceedingly high: an ultrahigh vacuum. 
 reinforcing precipitated silica for tire tread applications," Tire Technology International, p. 24 (1995).

(16.) A.Y. Coran and J.B. Domet, "The dispersion of carbon black in rubber - part I. Rapid method for assessing quality of dispersion," Rubber Chem. Technol., Vol. 95, p 973 (1992).

(17.) C.R. Herd, "Microscopical microscopical

pertaining to a microscope or to microscopy.
 view of polymer blends A polymer blend, polymer alloy, or polymer mixture is a member of a class of materials analogous to metal alloys, in which two or more polymers are blended together to create a new material with different physical properties.  and carbon black phase distribution," paper No. 2B, presented at the second International Tire Exhibition and Conference (1996).

(18.) J.L. Leblanc, "From peculiar flow properties to reinforcement in carbon black filled rubber compounds," Plastics, Rubber and Composites Processing and Application, Vol. 25, No. 5. p. 241-248 (1995).

(19.) R. Koopmann and J. Schnetger, "Eine rheologische mischungskontrolle," KGK KGK Kesintisiz Güç Kaynaklari , Vol. 39, No. 2 (1986).

(20.) S. Shiga, Mixing Technology, Int. Sci. and Technol., Vol. 16, No. 11, p. T/44. Reference NG 89/03/123; transl. Serial no. 11145 (1989).

(21.) B.B. Boonstra, "Resistivity resistivity

Electrical resistance of a conductor of unit cross-sectional area and unit length. The resistivity of a conductor depends on its composition and its temperature.
 of unvulcanized compounds of rubber and carbon black," Rubber Chem. Technol., Vol. 50, pp. 194-210, (1977).

(22.) W.M. Hess, "Characterization of dispersions," Rubber Chem. Technol., Vol. 64, p. 386 (1991).

(23.) A.N. Tabenkin, "New machine determines carbon black dispersion," Rubber and Plastics News, April 6 (1987).

(24.) B. Chung, J Menashi, B.E. Mackay and D.J. Curtis, "The influence of carbon black morphology morphology

In biology, the study of the size, shape, and structure of organisms in relation to some principle or generalization. Whereas anatomy describes the structure of organisms, morphology explains the shapes and arrangement of parts of organisms in terms of such
 and pellet pel·let
n.
1. A small pill; a pilule.

2. A small rod-shaped or ovoid mass, as of compressed steroid hormones, intended for subcutaneous implantation in body tissues to provide timed release over an extended period of time.
 properties on macro-dispersion," Rubber World, Vol. No. 6. p. 30-38 (1997).

(25.) C.D. Eisenbach and A. Ribbe, "Investigation of the distribution of fillers in natural rubber by element spectroscopic transmission microscopy microscopy /mi·cros·co·py/ (mi-kros´kah-pe) examination under or observation by means of the microscope.

mi·cros·co·py
n.
1. The study of microscopes.

2.
," KGK, Vol. 47, No. 5 (1994).

(26.) T. Alshut, R. H. Schuster and S. Kummer, "Raster-kraft-microskopie an elastomerwerkstoffen. Tell 1: Charakterisierung yon russmorfologie und russdispersion im `non-contact mode'," KGK, Vol. 47, No. 10, p. 702. (1994).

(27.) P.T.K. Shih and G.C. Goldfinger, "Filler dispersions in elastomers with imaging techniques," paper No. 52, presented at American Chemical Society, Rubber Division Meeting, Dallas, April 19-22 (1988).

(28.) W. Hader and C-J- Lorenzen, "RELMA RELMA Regenstrief LOINC Mapping Assistant (Regenstrief Institute)
RELMA Remote Laser Micro Analysis
RELMA Regional Educational Laboratory Mid-Atlantic (Rutgers) 
, on-line quality controlling the mixing room using laser analysis," Technische Mitteilungen Krupp 2 (1992).

(29.) Y. Li, M.J. Wang, T. Zang and X. Fu, "Study on dispersion morphology of silica in rubber," Rubber Chem. Technol., Vol. 67, pp. 693-699. (1994).

(30.) A.I. Medalia and D.F. Walker, "Evaluating dispersion of rubber," Technical Report RG-124 Revision #2. Cabot Corporation Cabot Corporation is a specialty chemicals and performance materials company. It operates in four segments: the Carbon Black Business, the Metal Oxides Business, the Supermetals Business, and the Specialty Fluids Business. Cabot's headquarters is located in Boston, Massachusetts. , 125 High Street, Boston, MA.

(31.) ASTM D2663-88. Standard test methods for carbon black-dispersion in rubber. American Society for Testing and Materials.

(32.) S.D. Lee, J.L. White, N. Nakajima and R. Brzoskowski, "A comparative study of characterization methods of carbon black dispersion in solution and emulsion emulsion: see colloid.
emulsion

Mixture of two or more liquids in which one is dispersed in the other as microscopic or ultramicroscopic droplets (see colloid). Emulsions are stabilized by agents (emulsifiers) that (e.g.
 SBR SBR - Spectral Band Replication  compounds prepared at various mixing levels," KGK, Vol. 42, pp. 992998 (1989).

(33.) A.Y. Coran and J.B. Donnet, "The dispersion of carbon black," KGK, Vol. 47, No. 5, p. 353 (1994).

(34.) ISO 11345; 1997(E), Rubber - assessment of carbon black dispersion - rapid comparative methods (1997).

(35.) N.A. Stumpe and H.E. Railsback, "Carbon black dispersion - photographic technique and rating system," Rubber World, Vol. 151, No. 3, p. 41 (1964).

(36.) S. Persson, "Determining black dispersion by split-field microscopy," European Rubber Journal, Nov. p. 28 (1978).

(37.) R.M. Haralick, K. Shanmugam and Its'hak Dienstein, "Texture features for image analysis, IEEE (Institute of Electrical and Electronics Engineers, New York, www.ieee.org) A membership organization that includes engineers, scientists and students in electronics and allied fields.  transactions on systems, man and cybernetics cybernetics [Gr.,=steersman], term coined by American mathematician Norbert Wiener to refer to the general analysis of control systems and communication systems in living organisms and machines. ," Vol. SMC-3, No. 6, November, p. 610 (1973).

(38.) R.J. Kadunce, "Carbon black dispersion utilizing the AMEDA AMEDA Arizona Middle Eastern Dance Association  system," BFGoodrich Co., Akron, Ohio 44318. Rubber Chem. Technol., Vol. 47, p. 469 (1974).

(39.) L.O. Andersson, S. Persson and L. Skoog, "Dispersion control for rubber manufacturers," presented at Polymer Testing at RAPRA RAPRA Rubber and Plastics Research Association (UK)  Technology Limited, 7-11th April. Proceedings: 4. Durability of Rubber, Paper 6 (1997).

(40.) A.N. Rasskazov, N.I. Shikhirev, M.I. Novikov and B.S. Grishin, "Effect of the magnification on the degree of dispersion on carbon black," Int. Polym. Sci. and Technol., 14, (4). Reference Kauchuk i Rezina 86/11/25; transl. Serial no. 10243. T/19- T/21. (1987).
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Author:Nilsson, L.
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Date:Mar 1, 1999
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