NMR of Reinforced Elastomers: Part II. The Influence of Carbon Black Dispersion

1982 ◽  
Vol 55 (4) ◽  
pp. 1095-1107 ◽  
Author(s):  
G. E. Wardell ◽  
V. J. McBrierty ◽  
V. Marsland
Keyword(s):  
Carbon Black ◽  
Rubber Compound ◽  
Average Quality ◽  
Degree Of Dispersion ◽  
Multiple Sampling ◽  
Polymer Formation ◽  
Specific Formulation ◽  
Carbon Black Dispersion

Abstract 1. NMR measurements can provide a fast and efficient monitor of the incorporation and dispersion of carbon black in a reinforced rubber compound. Tests can be carried out at all stages of processing, including masterbatch stock. 2. The technique provides a determination of the fraction of polymer which is bonded to the surface of the carbon black particles. Within a specific formulation, there is reasonably good correlation between the percentage of bonded polymer, determined by NMR, and the degree of dispersion of carbon black determined optically. 3. Bonded polymer formation is sensitive to carbon black type and to the nature of the host elastomer. In comparison of different formulations, there is no correlation between the fraction of bonded polymer and the dispersion of the black. However, carbon black-rubber attachments are fundamental to the phenomenon of reinforcement and, in this respect, NMR bonded-polymer measurements can provide a valuable probe for the investigation of reinforcement. 4. Samples taken from large internal mixers (capacity 200 kg) show that compound inhomogeneity on a gross scale necessitates multiple sampling in order to give an assessment of the average quality of the mix, irrespective of the technique used.

Ch.5 Content, third party rights and conditions, s.1: Content, Art.5.1.6

2015 ◽  
Author(s):  
Vogenauer Stefan
Keyword(s):  
Burden Of Proof ◽  
Third Party ◽  
Average Quality ◽  
Minimum Threshold ◽  
General Rules ◽  
A Performance

This commentary focuses on Article 5.1.6 of the UNIDROIT Principles of International Commercial Contracts (PICC) concerning the determination of the quality of performance. Under Art 5.1.6, where the quality of performance is neither fixed by, nor determinable from, the contract, a party is bound to render a performance of a quality that is reasonable and not less than average in the circumstances. The provision is a specific application of one of the general underlying principles of the PICC: the idea of favor contractus. This commentary discusses the priority of the general rules of contractual interpretation, average quality as a minimum threshold, standard of reasonableness, and burden of proof of the party alleging non-performance because of insufficient quality of performance.

Dispersion of Carbon Black in Rubber: Revised Calculation Procedure

1961 ◽  
Vol 34 (4) ◽  
pp. 1134-1140 ◽  
Author(s):  
A. I. Medalia
Keyword(s):  
Carbon Black ◽  
Microscopic Examination ◽  
Quantitative Comparison ◽  
Rubber Compound ◽  
Visual Appearance ◽  
Degree Of Dispersion ◽  
Quantitative Calculation ◽  
Glass Knife ◽  
Qualitative Estimation ◽  
Reinforcing Filler

Abstract Carbon black, the most important reinforcing filler for rubber, must be well dispersed if it is to function effectively. The state of dispersion of the carbon black can be studied effectively by microscopic examination of a thin (2µ) section of the rubber compound, using transmitted light, as described by Tidmus and Parkinson. Under the microscope, agglomerates of undispersed carbon black are visible. These agglomerates, which may range in size up to 100µ or even larger, are sectioned more or less cleanly by the glass knife, and appear as black or dark brown islands in a light brown field. While this method was originally proposed for qualitative estimation of the degree of dispersion, a quantitative calculation was subsequently developed by Leigh-Dugmore, by means of which the percentage of carbon black dispersed below a certain size was calculated. This calculation has been helpful in permitting a quantitative comparison of stocks of widely different visual appearance. As experience has accumulated with the Leigh-Dugmore method, some puzzling observations have been made. Frequently, the modulus level of a stock of a given dispersion was found to be higher than the proportionate modulus of a stock of 100% dispersion. Furthermore, stocks have occasionally been prepared with a measured dispersion rating of less than zero (see below). It thus seemed worthwhile to re-examine the Leigh-Dugmore calculation.

The Dispersion of Carbon Black in Rubber Part III. The Effect of Dispersion Quality on the Dynamic Mechanical Properties of Filled Natural Rubber

1992 ◽  
Vol 65 (5) ◽  
pp. 1016-1041 ◽  
Author(s):  
A. Y. Coran ◽  
J-B. Donnet
Keyword(s):  
Mechanical Properties ◽  
Carbon Black ◽  
Natural Rubber ◽  
Shear Strain ◽  
Dynamic Mechanical Properties ◽  
Dynamic Mechanical ◽  
Short Period ◽  
Dispersion Quality ◽  
Carbon Black Dispersion

Abstract The Part I of this series described a rapid method for determining the quality of carbon-black dispersion. The second paper (Part II) was concerned with the kinetics of the dispersion of carbon black into natural rubber (dispersion quality as a function of mixing time) in an internal mixer. In this paper we consider the effects of changes in dispersion quality on the dynamic mechanical properties of both unvulcanized and vulcanized natural rubber. The effects of changes in the degree of carbon-black dispersion were measured by using a new prototype moving-die rheometer (which is presently being developed at Monsanto Instruments & Equipment Research Laboratory). By using this prototype rheometer, G′ and G″ were measured as functions of shear-strain amplitude, temperature, and frequency. Increases in the degree of carbon-black dispersion in uncured natural rubber (starting from very poor dispersion quality) give decreases in the values of both G′ and G″. The decrease in dynamic moduli with increases in the degree of carbon-black dispersion might be explained on the basis of a network of agglomerates which exists when the quality of dispersion is extremely poor. In the case of uncured samples, values of G′, measured at low strains (e.g. ±1%), become reduced after the imposition of a larger (±50%) sinusoidal shear strain for a short period of time (e.g. 3 s). Then, with the passage of time, the reduced value of G′ partially recovers. The extent of this recovery increases with increases in the dispersion rating DR. Similar results were obtained with respect to the loss modulus G″. In both cases, the extent of recovery is much less when the carbon black is very poorly dispersed. The unrecoverable proportion of G′ or G″ is also considered to be due to a network composed of mutually interactive agglomerates of carbon black.

scholarly journals KETAHANAN USANG BARANG JADI KARET PEGANGAN SETANG SEPEDA MOTOR DARI TEPUNG KULIT KERANG

2016 ◽  
Vol 11 (1) ◽  
pp. 43-50
Author(s):  
Rahmaniar Rahmaniar
Keyword(s):  
Particle Size ◽  
Tensile Strength ◽  
Experimental Design ◽  
Carbon Black ◽  
Visual Test ◽  
Rubber Compound ◽  
Physical Test ◽  
Elongation At Break ◽  
Test Result

Padding used to strengthen and enlarge rubber volume, can improve the quality of rubbery goods’physical characteristics and vulcanization. The objectives of the research were to obtain the formulation ofrubber compound met SNI standardvaried with particle size of flour clamshell and ratio composition of padding(clamshell flour: carbon black). The experimental design of the research was Completely RandomizedFactorial Design. The first factor was concentration of clamshell flour in particle size (A): A1:30 phr, A2:40 phr, A3: 50 phr. The second was ratio composition of padding (clamshell flour: carbon black N330) (B):B1 = 15:55 phr, B2=25:45 phr and B3=35:35 phr. Testing on quality of rubber compound’s characteristicsincludevisual test, modulus, and ageing resistance including hardness, tensile strength, elongation at break.The result showed that visual test for physical compound characteristics value is no defect for all formula, 55– 104% for modulus, while compound physical test after ageing process shows 56 – 64 shore A for hardness,106 – 129 kg/cm2 for tensile strength, 336 – 579% for elongation at break. Test result for all parametersmeets SNI 06-7031-2004 as the standard for motorcycle grip handle.Keywords: rubber compound, Flour Clamshell, carbon black.

Studies in the Dispersion of SRF Carbon Black in Butyl Rubber

1953 ◽  
Vol 26 (1) ◽  
pp. 115-126
Author(s):  
F. P. Ford ◽  
A. Y. Mottlau
Keyword(s):  
Carbon Black ◽  
Light Transmission ◽  
Photometric Analysis ◽  
Simple Method ◽  
Degree Of Dispersion ◽  
Transmission Measurements ◽  
A New Technique ◽  
Control Work ◽  
Selection Of ◽  
Carbon Black Dispersion

Abstract A simple method is described for producing different degrees of carbon black dispersion in elastomers under controlled laboratory conditions. Careful selection of milling conditions has made possible the preparation of stocks possessing variations in degree of dispersion, comparable to the wide differences noted in practice. A new technique is described for studying these carbon black dispersions in rubber by means of the electron microscope. Such studies show large differences in degree of agglomeration of carbon black in compounds made under simple variations of conditions. Representative electron micrographs are shown. Good correlation is obtained between these micrographs and light transmission measurements of dilute solutions of the compounds. Such photometric analysis provides a simple method for the measurement of carbon black dispersion in research or control work. The observed differences in degree of dispersion have an effect on the physical properties of the unvulcanized compounds. This effect was observed by means of the parallel-plate plastometer. The viscosity values obtained with this instrument show a direct correlation with electron micrographic observations. Some of the practical and theoretical implications of this study are discussed with reference to recent work in this field by other investigators.

The Dispersion of Carbon Black in Rubber Part I. Rapid Method for Assessing Quality of Dispersion

1992 ◽  
Vol 65 (5) ◽  
pp. 973-997 ◽  
Author(s):  
A. Y. Coran ◽  
J-B. Donnet
Keyword(s):  
Carbon Black ◽  
Mixing Time ◽  
Poor Performance ◽  
Raw Material ◽  
Rubber Part ◽  
Reproducible Method ◽  
Internal Mixer ◽  
Kinetics Of ◽  
Carbon Black Dispersion

Abstract Carbon black is the most important reinforcing filler for rubbers. The incorporation of carbon black into rubber vulcanizates generally gives improved strength, extensibility, fatigue resistance, abrasion resistance, etc. In order to exert its beneficial influence on the properties of rubber vulcanizates, the carbon black must be sufficiently dispersed therein. Indeed, poor dispersion can, in itself, give rise to detrimental effects (e.g. reduced product life, poor performance in service, poor product appearance, poor processing characteristics, poor product uniformity, raw-material waste, high finished-product rejection rates, and excessive energy usage). These inadequacies are generally the result of the presence of rather large, undispersed agglomerates. The present work was initiated in order to develop an improved understanding of the carbon-black dispersion process including the understanding of factors which affect the kinetics of dispersion. The work described here is focused on methodology for reproducibly mixing carbon black with rubber in the laboratory, and reproducibility, but rapidly and easily estimating the degree of dispersion of the carbon black into the rubber as a function of mixing time. Procedures were developed for introducing rubber, filler, and other ingredients into a small, laboratory internal mixer and for mixing the batches for various periods of time. Also, an improved, simple-to-use, reproducible method for determining the degree of carbon black dispersion in rubber has been adapted. The extent of dispersion was correlated with various measures of tensile strength and with other performance-related properties.

Determination of the Degree of Dispersion of Carbon Black in Rubber Mixes

2009 ◽  
Vol 36 (3) ◽  
pp. 27-28 ◽  
Author(s):  
Yu. F. Shutilin ◽  
E. P. Bogachev ◽  
V. I. Molchanov
Keyword(s):  
Carbon Black ◽  
Degree Of Dispersion

Analysis of Resistivity in a Rubber Compound

1991 ◽  
Vol 64 (4) ◽  
pp. 501-509 ◽  
Author(s):  
D. Roig Fernández ◽  
A. J. Marzocca
Keyword(s):  
Electrical Resistivity ◽  
Carbon Black ◽  
Probability Model ◽  
Rapid Test ◽  
Rubber Matrix ◽  
Rubber Compound ◽  
Internal Factors ◽  
Tire Industry ◽  
Degree Of Dispersion ◽  
Electrical Conduction Mechanisms

Abstract In the tire industry, good dispersion of carbon black in the rubber matrix is very important to obtain optimum mechanical properties of the compound. Usually, this dispersion can be classified in macrodispersion (for particles bigger than 10 μm) and microdispersion (for those smaller than 10 μm). It is known that good microdispersion enables better fatigue resistance and wear. If it is desired to control the degree of dispersion of uncured compounds during the different processes in the factory, it would be necessary to have a simple and rapid test to do it. An appropriate method to detect different degrees of dispersion is based on the measurement of the electrical resistivity of the rubber compound with dc or ac. In recent years, different factors that affect the resistivity of the compounds were studied in several research programs. The internal factors include structure, size, and dispersion of carbon-black particles, the presence of other reinforcement (silica), and the polymer class. Other factors studied are external: mixing level, pressure, temperature, aging, and contact resistance. Boonstra showed that resistivity depends on the degree of dispersion of carbon black. In his paper, resistivity data are compared with the dispersion levels according to the Cabot rating with good correlation. Furthermore, there are several electrical conduction mechanisms that are proposed in the literature to explain experimental data. It is the purpose of this paper to present an improvement of the Boonstra device for the measurement of electrical resistivity of uncured compounds. The influence of temperature, pressure, aging, carbon black level, and time on the mill roll over the electrical resistivity were also studied. Finally, the results were analyzed by a probability model.

scholarly journals Preliminary Results of the Determination of Absolute Proper Motions of Stars Referred to Galaxies

1968 ◽  
Vol 1 ◽  
pp. 297-300
Author(s):  
N.V. Fatčihin
Keyword(s):  
Proper Motion ◽  
Focal Length ◽  
Probable Error ◽  
Proper Motions ◽  
Average Quality ◽  
Preliminary Results ◽  
Measuring Machine

Absolute proper motions have been determined for 14000 stars in the 82 areas indicated in Figure 1. These proper motions result from measures made on 105 plate pairs taken with the Pulkovo normal astrograph which has a focal length of 3·5 m. The plates, which had an average epoch difference of 22·4 years, were measured film-to-film in a Repsold measuring machine. The number of galaxies used for defining zero proper motion was 271, and among the stars measured were 1283 from the AGK3. The probable error of a determination of proper motion from one plate pair wasThe images of the galaxies were estimated as having an average quality of 6 on a scale of 10. (Deutsch et al., 1955).

Tingkat Pemahaman Kompetensi Guru Pada Mahasiswa Pendidikan Geografi Sebagai Calon Guru Geografi

2020 ◽  
Vol 21 (1) ◽  
pp. 102-117
Author(s):  
Novia Zalmita ◽  
Muhajirah Muhajirah ◽  
Abdul Wahab Abdi
Keyword(s):  
Prospective Teachers ◽  
Prospective Teacher ◽  
Quantitative Description ◽  
Population Data ◽  
Geography Education ◽  
Teacher Competence ◽  
Education Department ◽  
Long Time

One that influences human resource indicators is education. The teacher is a profession as a job of academic specialization in a relatively long time in college. Understanding related to teacher competence is very important to have by a prospective teacher because it can affect the quality of performance as a professional teacher. The teacher's competence is known as pedagogic, professional, social and personality competencies. The issue in this study is how the competency of the teacher of the Department of Geography Education FKIP Unsyiah as a prospective teacher of geography? The purpose of this study was to determine the competence of teachers in the Department of Geography Education FKIP Unsyiah as prospective geography teachers. Quantitative description approach is used in this study to find answers to the issue. The population in this study were students of the Department of Geography Education FKIP Unsyiah class of 2015 and 2016 who had been declared to have passed the Micro Teaching and Magang Kependidikan 3 course totaling 50 people. Because the population is small and can be reached, the determination of the sample using total sampling techniques so that the sample in this study is the whole population. Data collection is done by distributing test questions to respondents. The data was analyzed using the descriptive statistics percentage formula. The results of the study indicate that the level of teacher competence of Geography Education Department students as prospective teachers is in the moderate category, namely as many as 22 respondents (44%). A total of 12 respondents (24%) were in the high category, 15 respondents (30%) were in the low category and 1 respondent (2%) were in the very low category.

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