(REFERENCE OBJECT FOR TOPOGRAPHY OF MATERIALS)

Field of the Invention

The technical solution deals with the etalon to evaluate the topography of materials - reference object for topography of materials, which is intended for the calibration of a device evaluating the quality of filler macrodispersion.

Description of the Prior Art

Many methods for the monitoring of quality of fillers incorporation into the rubber matrix are in use across the rubber industry nowadays, since the quality of filler dispersion influences the performance properties of final products such as tires significantly. The quality of filler incorporation is described as the quality of filler macrodispersion standardly, which is the degree of the distribution of a filler in a compound, generally on a scale of less than 100 micrometers but greater than 2 micrometers representing micro range agglomeration. One of the most broadly used methods measuring the quality of macro dispersion of reinforcing fillers such as silica and carbon black, as well as fillers such as chalk, clay and other solids is, because of its rapidity and relative simplicity, an optical microscope in reflection mode evaluating the surface roughness of a freshly cut specimen described in the international standard ASTM D7723-11 "Standard Test Methods for Rubber Property - Macro-dispersion of Fillers in Compounds". This standardized method uses mathematical algorithms to quantify the surface roughness of a freshly cut rubber specimen as measured by a reflected light optical method when the specimen is cut and large agglomerates are pushed to one side or the other leaving a contoured surface where contours are referred as nodges. The sample preparation from an uncured compound is described in the document US 6,795,172 called "Method for preparing a cut surface in uncured rubber samples for measuring filler dispersion". The light microscope is equipped with a CCD (Charged Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor) sensor capturing surface images. The apparatus works in the dark field mode when an aperture is lit at a 30° angle for analysis. The sensor picks up the reflection of bumps on the surface where nodges represent undispersed filler whilst flat areas disperse the light out of a sensor thus in the sensor appear dark. The scan of a surface is digitalized and as a binary image analyzed by an image processing software. The procedure of analysis is described in the international standard ISO 11345/B called "Rubber - Assessment of Carbon Black and Carbon Black/Silica Dispersion - Rapid Comparative Methods". From the binary image, the ratio of the white area, represented by nodges, to the total area of the image can be calculated according to the ASTM D7723-11 providing the quality of filler macro dispersion in percentage.

Testing of rubber compounds has been carried out in order to determine properties and behavior of materials in rubber industry. Obtained characteristics can serve to monitor the manufacturing and processing processes and for the quality control of raw, semi- and final products. Rubber materials are known for their high molecular weight and very complex viscoelastic behavior, e.g. reversible deformation up to 1000 % at low compressibility. Because of their complex behavior, their processing is complicated. The behavior of these materials differs dependent on their composition and the type of each component in a compound. Then, single tests and conditions are necessary to be chosen according to the variability of rubber compounds. The viscoelastic response of materials will differ according to the test temperature, stress, frequency, the magnitude of imposed strain and many other parameters. Very important is the process of a sample preparation, because the precision of a preparation can influence test results significantly. Moreover, sample history, e.g. ageing, storage, are important also. In general, testing should be carried at the very similar (nearly the same) conditions as is the intended application of a product.

Summary of the Invention

Mentioned disadvantages and deficiency of today known techniques considerably solves the reference object for topography of materials intended for the calibration of a device evaluating the quality of filler macrodispersion according to the technical solution. The aim of a technical solution is the reference object made from a two-phase composite based on the incorporation of inert particles of globular shapes having diameters in the range from 0.5 to 500 micrometers and narrow size distribution with a variation coefficient up to 1 into a continuous phase.

Preferred diameter of the inert globular particles is in the range from 0.5 to 25 micrometers and its content is from 1 to 100 phr to 100 phr of the continuous phase.

The continuous phase can be formed by any polymer matrix based on an elastomer, preferably a silicon rubber, any polymer matrix based on a thermoplastic material or a polymer matrix based on a thermoset. Alternatively, as the continuous phase a low-molecular weight organic material as wax, paraffinic oil or glue can be used.

Inert globular particles are preferably glass spheres, but also particles of organic nature, e.g. carbon black, ceramic spheres or metal spheres.

The reference object for topography of materials according to the invention improves the process of evaluation of macrodispersion quality based on the surface roughness of a freshly cut sample. This is due to its ability to calibrate the device measuring macrodispersion of a compound based on the surface topography.

Brief Description of the Drawings

To give a better insight to the technical solution following drawings are attached:

FIG. 1. Schematic drawing of a principle of an optical microscope in dark field illumination.

FIG. 2. The exemplification of carbon black agglomerates size distribution.

FIG. 3. The exemplification of glass-spheres size distribution, which is much narrower than that of carbon black agglomerates.

Description of Preferred Embodiments

To a further clarification of the aim of a technical solution serve the following examples of a particular implementation.

Example 1 (preferred realisation)

The reference object for topography of materials is made from a two-phase composite material where the continuous phase is composed of 100 phr of silicon rubber and 10 phr of cross-linking agent and the discrete phase is composed of 1 phr of inert globular particles - specifically glass spheres having diameter from 0.5 to 25 micrometers and narrow size distribution with a variation coefficient up to 1 (graphically exemplified in FIG. 3).

When the reference object is manufactured, silicon rubber in a liquid phase is measured into a beaker, where is mixed with a cross-linking agent. Subsequently, a specific amount of glass spheres is added. This compound is being stirred by an electrical stirrer for 5 minutes at velocity 300 revolutions per minute at room temperature. The prepared suspension is transformed into a mould having required dimensions, considering the minimal area of the reference object being investigated is, according to ASTM D7723, 5 by 5 millimeters. Subsequently, the suspension is inserted into a vacuum oven for at least half an hour and deaerated (a desiccator can be used alternatively also). After a deaeration the suspension is heated up to 40±5 °C for at least 1.5 hour, up to a cross-linking process is complete.

The produced reference object is intended to use for the calibration of a device evaluating filler macrodispersion - light microscope equipped by CCD or CMOS sensor capturing scans of a surface of a freshly cut specimen. The microscope (FIG. 1) works in a dark field mode, when the sample 1 is lit by the light from the source 4 at 30° angle for the purpose of analysis. The sensor 3 through the objective 2 picks up the reflection of bumps on the surface where nodges represent undispersed filler whilst flat areas disperse the light out of sensor thus in the sensor appear dark. The scan of a surface is digitaliied and as a binary image analyzed by the image processing software.

Example 2

The reference object for topography of materials is made from a two-phase composite material where the continuous phase is 100 phr of polypropylene and the discrete phase is 5 phr of glass spheres having diameter from 25 to 75 micrometers and narrow size distribution.

When the reference object is manufactured, polypropylene granulate is poured into a chamber of an integral mixer heated to 200 °C at the zero time and homogenized for two minutes at speed 20 revolutions per minute. After this time, the specific amount of the glass spheres is added and the number of revolutions is increased to 50 revolutions per minute in a one minute interval at continuous mixing. At this speed, the compound is being mixed for four minutes and the mixing process is finished when the chamber is emptied. It is a one-step mixing process. Subsequently, samples for the test can be prepared.

Example 3

The reference object for topography of materials is made from a two-phase composite material where the continuous phase is a thermoset prepared from 100 phr of Bisfenol A diglycidylether and 6 phr diethylentriamine and the discrete phase is 10 phr of glass spheres having diameter from 75 to 150 micrometers and narrow size distribution.

When the reference object is manufactured, Bisfenol A diglycidylether is measured into a beaker, where is mixed with glass spheres at temperature 80 °C and speed 300 revolutions per minute. When the compound is cooled down, the dietylentriamin is incorporated and the whole mixture is transformed into a mould having required dimensions, considering the minimal area of the reference object being investigated is, according to ASTM D7723, 5 by 5 millimeters. Subsequently, the suspension is inserted into a vacuum oven for at least half an hour and deaerated (a desiccator can be used alternatively also). After a deaeration the suspension is heated up to 80±5 °C for at least 8 hours. After 8 hours the temperature is elevated to 120 °C for 2 hours in order to complete the cross-linking process.

Example 4

The reference object for topography of materials is made from a two-phase composite material where the continuous phase is binary glue composed of 50 phr of polystyrene dissolved in 100 phr of acetone. This is transformed onto the laboratory glass and 15 phr of glass spheres having the diameter from 150 to 300 micrometers and narrow size distribution are dispersed in the mixture manually.

Example 5

The reference object for topography of materials is made from a two-phase composite material where the continuous phase is composed of 100 phr of silicon rubber and 10 phr of cross-linking agent and the discrete phase is composed of 25 phr of inert globular particles - specifically glass spheres having diameter from 300 to 450 micrometers and narrow size distribution with a variation coefficient up to 1 (graphically exemplified in FIG. 3).

When the reference object is manufactured, silicon rubber in a liquid phase is measured into a beaker, where is mixed with a cross-linking agent. Subsequently, a specific amount of glass spheres is added. This compound is being stirred by an electrical stirrer for 5 minutes at velocity 300 revolutions per minute at room temperature. The prepared suspension is transformed into a mould having required dimensions, considering the minimal area of the reference object being investigated is, according to ASTM D7723, 5 by 5 millimeters. Subsequently, the suspension is inserted into a vacuum oven for at least half an hour and deaerated (a desiccator can be used alternatively also). After a deaeration the suspension is heated up to 40±5 °C for at least 1.5 hour, up to a cross-linking process is complete.

Example 6

The reference object for topography of materials is made from a two-phase composite material where the continuous phase is composed of 100 phr of silicon rubber and 10 phr of cross-linking agent and the discrete phase is composed of from 1 to 100 phr carbon black commonly used in rubber industry defined according to the international standard ASTM D1765-10.

Exemplification of carbon black aggregate size distribution is shown in FIG. 2.

When the reference object is manufactured, silicon rubber in a liquid phase is measured into a beaker, where is mixed with a cross-linking agent. Subsequently, a specific amount of carbon black is added. This compound is being stirred by an electrical stirrer for 5 minutes at velocity 300 revolutions per minute at room temperature. The prepared suspension is transformed into a mould having required dimensions, considering the minimal area of the reference object being investigated is, according to ASTM D7723, 5 by 5 millimeters. Subsequently, the suspension is inserted into a vacuum oven for at least half an hour and deaerated (a desiccator can be used alternatively also). After a deaeration the suspension is heated up to 40±5 °C for at least 1.5 hour, up to a cross-linking process is complete.

Example 7

The reference object for topography of materials is made from a two-phase composite material where the continuous phase is composed of 100 phr of silicon rubber and 10 phr of cross-linking agent and the discrete phase is composed of 30 phr of inert globular particles - specifically metal spheres having diameter from 350 to 500 micrometers and narrow size distribution.

When the reference object is manufactured, silicon rubber in a liquid phase is measured into a beaker, where is mixed with a cross-linking agent. Subsequently, a specific amount of metal spheres is added. This compound is being stirred by an electrical stirrer for 5 minutes at velocity 300 revolutions per minute at room temperature. The prepared suspension is transformed into a mould having required dimensions, considering the minimal area of the reference object being investigated is, according to ASTM D7723, 5 by 5 millimeters. Subsequently, the suspension is inserted into a vacuum oven for at least half an hour and deaerated (a desiccator can be used alternatively also). After a deaeration the suspension is heated up to 40±5 °C for at least 1.5 hour, up to a cross-linking process is complete.

Industrial Utilizabilitv

Technical solution is allowed to use for the calibration of a device evaluating filler macrodispersion in a continuous matrix.