Thermal Analysis of Petrochemicals
On Demand Webinar

Thermal Analysis of Petrochemicals

On Demand Webinar

"Thermal Analysis of Petrochemicals" describes methods used to characterize petrochemical materials

Thermal Analysis of Petrochemicals
Thermal Analysis of Petrochemicals

Thermal analysis methods help you to address issues directly related to the quality and processing of oil and oil-based products in the petrochemical industry.
The methods can be used to measure the properties of materials as a function of temperature or time over a wide temperature range, starting at –150 °C in compliance with many international standards.

In this Webinar, we will show how thermal analysis is used to analyze materials in the petrochemical industry and present some typical examples of samples measured by DSC, HP DSC, TGA, TOA, and DP techniques.

40:49 min
English

The Webinar covers the following topics:

  • Introduction
  • Petrochemicals
  • Industries and Applications
  • International Standards
  • Thermal Analysis
  • Effects and Applications for:
    - Differential Scanning Calorimetry (DSC and HP DSC)
    - Thermogravimetric Analysis (TGA)
    - Thermo-optical Analysis (TOA)
    - Dropping and Softening Points (DP)
  • Summary

In the webinar titled "Thermal Analysis of Petrochemicals", we describe a number of examples that illustrate how thermal analysis can be used to investigate the physical properties and behavior of petrochemicals.

Industrial applications of Petrochemicals

Petrochemical compounds are derived from crude oil, making this raw material the starting point and basis for very many products. The products include fuels, different kinds of chemicals and practically everything made of plastics. This is why the analysis of petrochemical compounds is so important.

Crude oil production currently amounts to about 1000 million tons per year and is still growing. Approximately 90% is used as fuel and gasoline, while about 10% is converted to chemicals and plastic materials.

 

Thermal analysis of petrochemicals

The most important effects that can be analyzed by DSC are the glass transition, melting and crystallization behavior, transition and reaction enthalpies, and thermal stability.

TGA is normally used to study compositional analysis, thermal stability and decomposition, evaporation and desorption behavior.

TOA is the method of choice for characterizing optical properties such as changes in morphology and cloud point effects.

The main applications of DP are the dropping and softening points for material characterization.

Thermal Analysis of Petrochemicals

Slide 0: Thermal Analysis of Petrochemicals

Ladies and Gentlemen,

Welcome to the METTLER TOLEDO webinar on the Thermal Analysis of Petrochemicals.

 

As we all know, the oil and energy industry is extremely large, and petroleum is the single largest source of energy used in the world today.

Petrochemical compounds are derived from crude oil, making this raw material the starting point and basis for very many products. The products include fuels, different kinds of chemicals and practically everything made of plastics. This is why the analysis of petrochemical compounds is so important.

 

Thermal analysis is an excellent method for identifying and characterizing petrochemical materials because their properties are strongly temperature dependent.

 

Slide 1: Contents

This slide lists the main topics I want to cover.

 

First, I would like to discuss the most important thermal properties of petrochemicals and describe the thermal analysis techniques that can be used to measure them.

The techniques include:

Differential Scanning Calorimetry, or DSC,

Thermogravimetric Analysis, or TGA,

Thermo-optical Analysis, or TOA,

And finally, instruments for dropping and softening point determination, DP and SP.

 

I will then present a number of examples that illustrate how thermal analysis can be used to investigate the physical properties and behavior of petrochemicals.

 

Finally, I want to summarize the different thermal analysis techniques and their application fields and list a number of useful references for further information and reading.

 

Slide 2: Introduction

 

The steps involved in the petrochemical production chain are summarized at the top of the slide. They include the identification and processing of raw materials and feedstock, the production of primary petrochemicals, transport and storage, and the refining of petroleum products to intermediates and derivatives or to fuel.

 

Thermal analysis techniques and methods can be used to characterize materials and to provide specific information about material quality, crystallization and stability, as well as on the composition of mixtures and the influence of additives.

 

 

Slide 3: Introduction

The word petroleum originates from the Greek word petra, meaning rock, and the Latin word oleum, meaning oil.

Petroleum is a generic term applied to oil and oil products in all forms, such as crude oil, unfinished oils, petroleum products, natural gas, liquids, and hydrocarbon compounds blended into finished products.

 

Crude oil and petroleum products are multicomponent systems of varying chemical composition. They are predominantly mixtures of hydrocarbons, usually accompanied by small quantities of hetero-compounds containing atoms such as sulfur, nitrogen and oxygen in addition to carbon and hydrogen. Final, commercial products are also generally mixtures.

 

Crude oil production currently amounts to about 1000 million tons per year and is still growing. Approximately 90% is used as fuel and gasoline, while about 10% is converted to chemicals and plastic materials.

 

Slide 4: Applications Related to Petrochemicals

The table summarizes the extremely wide application field of thermal analysis for petrochemicals.

 

No matter in which sector you are involved in the petrochemical industry chain, thermal analysis techniques will help you address issues related to the quality and manufacture of oil and oil-based products.

Thermal Analysis can be used for quality control and research in upstream activities related to exploration, production, transport and storage, or downstream, in refinery processes and for the production of petrochemicals and lubricants.

 

Thermal analysis techniques and methods are employed for measuring melting and crystallization behavior, for investigating compositional profiles and thermal and oxidative stability for optimizing processes, and for studying the dropping and softening behavior of materials. We will look at some of these applications in more detail during the course of the presentation.

 

Slide 5: Thermal Analysis Test Methods

Since the techniques are widely used in quality control, most of the analytical methods are defined in international test methods. The field of petroleum analysis is internationally highly standardized.

Most of the tests on oil products in laboratories and refineries are carried out according to test methods described by:

ASTM International (known up until 2001 as the American Society for Testing and Materials)

or the EI (the Energy Institute, set up in 2003 as a result of a merger between the Institute of Petroleum and the Institute of Energy).

 

The table lists some examples of standard test methods for crude oil, distillates, waxes, and greases. The methods describe procedures for the determination of transition temperatures, the oxidation induction time (OIT), the oxidation onset temperature (OOT), evaporation loss, dropping and softening points, and the wax appearance temperature.

 

METTLER TOLEDO instruments allow analyses to be performed in full compliance with the different test methods.

 

I would now like to move on and discuss different aspects of thermal analysis in more detail.

 

Slide 6: Thermal Analysis

What exactly is Thermal Analysis?

The ICTAC definition is:

“A group of techniques in which a physical property of a substance is measured as a function of temperature whilst the substance is subjected to a controlled temperature program”.

The schematic diagram on the right shows a simple linear temperature program in which the temperature of a sample is increased at a constant heating rate.

 

The lower half of the slide illustrates typical events and processes that occur when a sample is heated. These include initial melting in which the sample changes from the solid to the liquid state, followed by oxidation if the sample is exposed to air or oxygen, and finally decomposition.

Thermal analysis techniques are widely used in quality control and in research and development to measure properties such as heat capacity, the change in sample mass, and chemical stability to name just a few.

 

Slide 7: Thermal Analysis Techniques

The slide shows the four most important thermal analysis techniques that are employed to characterize petrochemicals:

 

DSC is probably the most widely used technique. It allows you to determine the energy absorbed or released by a sample as it is heated, cooled or held at constant temperature.

The picture shows a DSC sensor with a crucible containing a sample, and a reference crucible.

TGA measures the mass of a sample as a function of temperature in a defined atmosphere.

The picture shows the unique METTLER TOLEDO ultra-micro balance with its automatic internal ring weights.

TOA monitors optical properties as a function of temperature, either via microscopy or video camera.

Finally, DP determines the dropping or softening properties of a given material.

 

I will explain these techniques in more detail in the following slides and describe some application examples.

 

Slide 8: DSC, HPDSC, Flash DSC

Let’s begin with DSC.

This technique allows us to measure the amount of heat absorbed or released by a sample as it is heated or cooled.

DSC instruments are available in different versions and differ in their temperature range, the type of sensor used, and their heating and cooling rates.

The standard METTLER TOLEDO DSC 1 instrument operates from minus one hundred and fifty degrees Celsius (–150 °C) to plus seven hundred degrees (700 °C) at heating rates of up to three hundred kelvin per minute (300 K/min). Samples are normally measured in small crucibles made of aluminum, alumina or other materials, using sample amounts of two to twenty milligrams.

 

The schematic curve on the left shows a typical DSC measurement curve of a semicrystalline petrochemical compound. Exothermic effects point in the upward direction and endothermic effects downward. The effects are numbered next to the curve and explained in the table. These are:

One, the initial deflection or start-up transient of the DSC;

Two, the baseline where no thermal effects occur;

Three, a glass transition with enthalpy relaxation;

Four, cold crystallization;

Five, melting of the crystalline fraction; and finally

Six, oxidative exothermic decomposition.

 

Special instruments, enable samples to be measured at higher or lower gas pressures (in pressure- or high-pressure DSC equipment), or at ultra-fast heating and cooling rates (the so-called Flash DSC technique).

 

The METTLER TOLEDO HP DSC 1 is an extremely versatile high-pressure DSC instrument. It can analyze samples under inert or reactive gases at pressures of up to ten megapascals (10 MPa). This suppresses undesired vaporization of samples and allows the stability of samples to be studied at increased oxygen pressures.

 

Slide 9: Differential Scanning Calorimetry (DSC)

The table summarizes the main analytical applications of DSC for petrochemicals.

They include the measurement of glass transitions, specific heat capacity curves, the enthalpy of reactions, crystallization processes, reaction kinetics and thermal stability. This information can be used to identify compounds and to define the working range of materials.

DSC methods can be employed in quality control and the analysis of raw materials as well as for studying the effect of additives. The measurement of reactions such as oxidation reactions is also an important application.

The picture on the right shows a view of an open DSC furnace with sample and reference crucibles.

 

Slide 10: Application 1: DSC                              Characterization of composition

The first application demonstrates the use of DSC to characterize different petroleum fractions, for example by their glass transition temperature and melting behavior.

 

The diagram shows the DSC heating curves of crude oil, bitumen and gasoline. The samples were first cooled to below minus 150 degrees Celsius at 10 kelvin per minute. They were then heated at 5 kelvin per minute to 50 to 120 degrees, depending on the sample.

The curves exhibit various effects. The steps indicated by Tg in the curves at low temperature correspond to the individual glass transitions of the samples. The crystallized fractions then melt over a wide temperature range. This gives rise to several broad, overlapping endothermic peaks indicated by the shaded areas between each curve and its baseline. The melting behavior is directly related to the size and weight distribution of crystals and is characteristic for a particular distillate or crude oil.

 

In the case of gasoline shown in the bottom curve, the glass transition is followed by a small exothermic peak. This occurs quite often and is due to the crystallization of iso-alkanes.

 

Slide 11: Application 2: DSC                                                      Oil content in wax

The next application shows how DSC can be employed to characterize oil-wax mixtures.

DSC methods provide a convenient way to determine the content of wax in oils or, as in this example, the content of oil in waxes over a very wide concentration range.

The method consisted of recording the DSC melting profiles of reference samples of wax with known percentages of oil. The curves are displayed on the right of the diagram.

The normalized enthalpy of melting of the wax fraction shown by the shaded area between each curve and its baseline correlates directly with the composition of the oil-wax mixture. The data was used to construct the calibration plot shown on the left side of the diagram.

A sample with unknown oil content can then be measured under the same conditions. The value obtained for the normalized enthalpy of melting is used to calculate the oil content in the wax as indicated by the dotted red lines and arrows in the calibration plot.

 

Slide 12: Application 3: DSC                  Wax appearance temperature by IP 389

Crude oils and their distillates present potential production, transportation and storage problems.

Variation in temperature is the main factor affecting the properties of crude oil distillates. If the temperature falls below the wax appearance temperature, there is a high risk that wax will be deposited on the inside walls of the pipelines, resulting in reduced flow, a pressure drop and, possibly, blockage of the pipeline.

 

The wax appearance temperature can be determined in a DSC cooling experiment. The temperature range and cooling rate depend on the type of distillate, for example with crude and heavy oils, in the temperature range plus 80 to minus 20 degrees Celsius at a cooling rate of 2 kelvin per minute, and with medium heavy fuel oils from plus 25 to minus 30 degrees.

The wax appearance temperature is determined as the onset of the wax crystallization in the DSC cooling curves. The position of the curves indicates the temperature at which the crystallization processes occur. The wax appearance temperature defines the lowest temperature at which the product can be used in certain applications.

The diagram shows cooling DSC curves of three different diesel fuels, labeled A, B, and C. Diesel fuels B and C contained an additive that lowered the wax appearance temperature by about 10 degrees compared with Diesel A, which contained no additive. This indicates that B and C remain liquid at lower temperatures than Diesel A.

 

Slide 13: Application 4: HPDSC                          OIT by ASTM D6186

The determination of the oxidation induction time (or OIT) of oils is an important test in the petrochemical industry. The test is usually performed according to a standard, for example ASTM D6186.

 

The diagram displays the OIT curves of two different types of lubricating oils. The samples were held at one hundred and eighty degrees Celsius (180 °C) at a constant oxygen pressure of three point five megapascals (3.5 MPa) until exothermic oxidation began.

The black curve was obtained from a mineral oil and the red curve from a synthetic oil. The mineral oil oxidized after about 35 minutes and the synthetic oil after about 237 minutes. This indicates that the synthetic oil is much more stable than the mineral oil under the conditions used.

 

In general, synthetic oils are very stable and take a long time to oxidize. High-pressure DSC is therefore ideal for measuring the OIT of lubricating oils because the measurement time at a given isothermal temperature can be shortened by increasing the oxygen pressure. At the same time, higher pressure also suppresses vaporization of the oil.

 

Slide 14: Application 5: DSC                                          Identification of polymers

The slide summarizes DSC measurements of the melting peaks of commonly used polymers derived from petroleum-based products. The peaks clearly differ in their size and position on the temperature axis.

The melting peak and melting range are important properties of plastics. The temperatures at which melting occurs determine the usable temperature range of manufactured parts and are important for defining processing conditions. The melting profile is also used for identification purposes, for example in quality control.

The normalized enthalpy of melting is determined by integrating the shaded area between the peak and the baseline. The degree of crystallinity can then be determined if suitable standards are available.

Here again, we see that DSC melting curves provide a reliable way to identify polymers and check quality in production.

 

Slide 15: Application 6: Flash DSC                                             Crystallization

This application was performed using the Flash DSC 1, a rapid-scanning DSC with ultra-high heating and cooling rates.

In this example, we are talking about cooling rates of ten to 500 kelvin per second or more, compared with rates of 10 kelvin per minute (10 K/min) typically used in conventional DSC instruments.

The use of high heating and cooling rates enables materials to be analyzed without interference from reorganization processes, because there is no time for such processes to occur. This information is extremely valuable for the optimization of technical processes.

 

The Flash DSC 1 is the ideal tool for studying crystallization kinetics. The diagram shows the cooling behavior of isotactic polypropylene (iPP) as a function of the cooling rate. The peak temperature shifts to lower temperatures at higher cooling rates This is indicated by the dotted red line drawn in the range 80 to 110 degrees Celsius.

At rates above fifty kelvin per second (50 K/s) the formation of the mesophase is also observed at about 30 degrees in a second crystallization process, as indicated by the dotted blue line.

At cooling rates above 500 kelvin per second (500 K/s), no crystallization occurs. The material remains amorphous with a glass transition at about minus ten degrees (-10 °C).

 

Slide 16: TGA/DSC

Now let’s turn our attention to thermogravimetric analysis, or TGA.

In this technique, the mass of a sample is continuously measured as it is heated or cooled in a defined atmosphere. We simply put a few milligrams of the sample into a crucible, weigh the sample, heat it and record the weight change. From this, we can obtain information about the composition of the sample such as the main component, for example an oil or a polymer, and an additive, for example a filler.

 

The schematic curve on the left shows the typical TGA measurement curve of a petrochemical compound. Initially, before the heating ramp begins, the TGA measures the mass of the sample. At the end of the measurement, inorganics and ashes remain behind as a residue after heating to high temperatures. The steps due to loss of mass give us valuable information about the composition of materials.

 

The steps are numbered next to the curve and explained in the table. These are:

One, heating begins and volatile components vaporize;

Two, pyrolysis of organic substances and polymers;

Three, at some point, the atmosphere is switched from nitrogen to oxygen to obtain oxidative conditions;

Four, carbon black or soot burns;

Five, inorganics and ashes are left behind as a residue.

 

Slide 17: Thermogravimetric Analysis (TGA)

TGA is used to investigate vaporization or decomposition processes. Evolved gases can be analyzed online using hyphenated techniques such as TGA-MS or TGA-FTIR.

 

The table on the left summarizes the main analytical applications of TGA for petrochemicals. The technique provides information about the composition of samples. Furthermore, it allows us to check the thermal or oxidative stability of products and to analyze the content of moisture or volatiles in formulated products.

 

The picture on the right shows a view of the open furnace, a sample holder with two positions for the sample and reference crucibles in a TGA/DSC instrument. The standard crucibles are made of alumina.

 

Slide 18: Application 1: TGA/DSC                                               Effect of additives

The first TGA application on this slide shows the combustion profile of three samples of biodiesel fuel. The resistance towards oxidation is used to determine the quality and economic value of different types of biodiesel.

 

TGA measurements allow the combustion profiles of biodiesel samples containing different additives to be compared. In this example, the combustion profiles of two samples of biodiesel containing additives designated A and B were compared with the combustion profile of a sample of pure biodiesel.

 

Approximately ten milligrams (10 mg) of sample was heated from room temperature to four hundred degrees Celsius (400 °C) in an air atmosphere. The TGA curves exhibit one broad weight-loss step.

The blue curve is the result for biodiesel containing additive B. The curve shows that the oxidative degradation of this sample is shifted to higher temperatures compared with the degradation of pure biodiesel. In contrast, the additive A does not produce any significant effect.

 

The first derivative or DTG curves of the TGA curve shown in the lower diagram help us to determine the maximum rate of mass loss. The TGA step is now observed as a large DTG peak. The maximum of the DTG peak of biodiesel containing additive B is shifted to higher temperatures compared with the maxima of the other two samples.

 

This type of analysis is used to assess the antioxidant capabilities of different additives. Additive B is more effective, in terms of inhibiting the degradation process and improving the stability of the biofuel.

 

Slide 19: Application 2: TGA/DSC                       Noack volatility by ASTM D6375

The next slide gives describes the Noack test.

This test is a widely used standard test method to assess the volatility or evaporation loss of lubricating oils. The ASTM standard test method D6375 makes use of thermogravimetric analysis.

Noack evaporation loss is determined in comparison with a reference oil sample. Knowledge of the evaporation behavior is crucial because the more the oil vaporizes, the thicker and denser it becomes, leading to increased oil consumption, coking and wear.

 

According to the ASTM procedure, a Noack reference oil is quickly heated to 249 degrees Celsius (249 °C) in a flow of air and is then held isothermally for an appropriate time at this temperature. The blue curve shows the sample temperature profile and the black curve the resulting TGA curve. The Noack evaporation loss is defined as the loss in mass up to the Noack reference time. This is indicated by dashed black arrows.

 

The sample of interest is then measured under the same experimental conditions. This is the red curve. The Noack volatility or evaporation loss of the sample is then read off from the TGA curve at the Noack reference time.

 

The TGA measurement can be automated. The METTLER TOLEDO TGA system with a sample robot and automated evaluation provides high sample throughput and rapid pass/fail assessment of individual oils.

 

Slide 20: Application 3: TGA/DSC                                                           Soot content

The test procedure described in this slide is part of the ASTM D5967 test method for the evaluation of diesel engine oils and is commonly referred to as Mack T-8. This test method covers an engine test procedure for evaluating performance characteristics. In particular, TGA experiments provide information about soot concentrations.

Depending of the soot content, the engine oil may cause sludge formation, wear and filter plugging.

 

METTLER TOLEDO TGA/DSC instruments simultaneously measure the mass loss and the DSC heat flow signal of the same sample. The DSC curve provides additional information that can be used to identify thermal events.

 

The complex temperature program is specified in the test method and involves a series of heating and isothermal segments. At temperatures below 650 degrees Celsius (650 °C) the experiment is run in a nitrogen atmosphere. At 650 degrees, the atmosphere is switched to oxygen. This is automatically performed using a gas controller installed in the TGA/DSC.

The slide summarizes the results obtained from three engine oil samples labeled A, B, and C. The TGA curves are displayed in the upper diagram, and the DSC curves in the lower diagram. The weight loss steps up to 650 degrees are due to the loss of volatile oil components in nitrogen and exhibit only rather small endothermic effects. In contrast, the combustion of soot after switching to oxygen produces a large exothermic effect that is shown as a large DSC peak.

 

The TGA and DSC curves resulting from the combustion of soot above 650 degrees indicates that the soot content of each sample is different. Engine oil C contains almost no soot.

Using TGA, we can easily determine the soot content and distinguish between the samples.

 

Slide 21: Thermo-Optical Analysis (TOA)

Let’s now turn to thermo-optical analysis or TOA for short.

TOA techniques measure optical properties of a sample as it is heated or cooled. The properties can be monitored by DSC, HPDSC or HotStage systems in combination with a microscope or a video camera. The HPDSC instrument can also be  connected to a chemiluminescence accessory. Some TOA systems allow calorimetric effects to be measured simultaneously while making visual observations.

The table lists the most important analytical applications of TOA for petrochemicals, such as changes in morphology, shrinkage, and crystallization behavior. In addition, thermochromism and the oxidative stability of samples can also be measured.

 

The picture shows a hot-stage measuring cell for visual sample observation. A microscope and a video camera connected to the measuring cell allow video images to be captured and overlaid with the real-time temperature.

The next slide illustrates such a measurement.

 

Slide 22: Application 1: TOA                                                       Cloud point

Here we see an example in which microscopy has been combined with DSC. This allows the crystallization process to be observed and recorded visually. Clouding in biodiesel is caused by small particles of wax that precipitate out of the diesel fuel as the temperature of the sample drops. The wax forms large flat crystals that can quickly block fuel lines and fuel filters.

 

The slide displays the DSC cooling curves of three different samples of biodiesel. The cooling curves of all three samples are very similar. The crystallization process occurs at around minus forty-four degrees Celsius (-44 °C). The images captured at minus sixty degrees (-60 °C) indicate that the crystalline morphology of each sample is different. In this case, the visual information helps to interpret processes in addition to the DSC results.

 

Slide 23: Application 2: TOA                               HP DSC-Chemiluminescence

This slide shows the results of a chemiluminescence experiment performed using a thin film of polypropylene.

The measurements were carried out using a HPDSC 1 equipped with the chemiluminescence accessory and a high-sensitivity CCD camera. The aim was to obtain information about the thermal stability of the material.

The specimen was measured isothermally at one hundred and thirty degrees Celsius (130 °C) in an oxygen atmosphere. The diagram shows the chemiluminescence intensity curve and emission images captured at different times. Evaluation of the intensity curve indicates that the onset of oxidation begins at about 230 minutes. The emission image at 205 minutes, however, shows a region at the lower edge of the sample where light emission has already begun. This is the initial oxidation reaction. In the image at 285 minutes, three main regions of reaction are visible. The regions are highlighted by the arrows in the box. With increasing reaction time, the regions spread until finally the entire sample emits light.

The results indicate that the reaction spreads from localized nuclei. The orientation of the nuclei indicates that they originated as a result of the manufacturing process.

 

Slide 24: Dropping (DP) and Softening Points (SP)

The Dropping Point Systems allow you to determine the dropping- and softening-points of pitch, asphalt, polymers, resins, waxes and many other materials in fully automatic operation. Standard-compliant cups and measurement methods guarantee that the results can be meaningfully compared.

 

The dropping point measurement records the temperature at which the first drop of a substance falls from a cup under defined test conditions. The softening point is the temperature at which a sample has flowed a certain distance.

 

The picture on the right shows the Dropping Point System and the innovative sample carrier that allows you to simultaneously measure two samples.

 

The instrument can be operated in two different modes namely to determine the dropping point or the softening point. Visual camera observation and digital image analysis guarantee that the values of results are reliable.

 

Slide 25: Application 1: DP                                                        ASTM D3954

The dropping point test is commonly used for selecting raw materials and for monitoring the quality of petroleum wax-based products.

 

Wax-based emulsions are used in a number of industrial applications, for example the coating of fibrous cellulose products such as paper, food wrappers and boxboard. The emulsions are often used alone or in combination with other ingredients. The blends used may be present in different combinations, including hot-melt wax mixtures and powder mixtures.

 

The ASTM D3954 standard is the official test method used to for determining the dropping point of waxes.

 

The picture on the left shows the moment when the liquid drop is detected.

 

The table on the right summarizes the results of measurements performed on an ethylene-vinyl acetate copolymer (EVA), a polyethylene homopolymer (PE) and an ethylene-propylene copolymer (EP).

The results obtained are listed in the first row and agree well the specified nominal values supplied by the manufacturer given in the second row. The value of the standard deviation in the bottom row shows the repeatability of such measurements for the specified materials.

 

Slide 26: Application 2: SP                                                         ASTM D3104

Asphalt and pitch do not go through a distinct solid-liquid phase transformation when heated, so a precise melting point cannot be assigned. As the temperature increases, the materials gradually change from being brittle or thick pasty solids to softer and less viscous liquids.

Softening-point tests must therefore be performed in precisely defined experiments using an approved standard such as ASTM D3104 in this example. Special sample cups and methods ensure that the results are reproducible and that they can be meaningfully compared. The measurements yield important information and criteria to assist in the selection of mixtures with suitable binders for production and at the same time provide excellent product quality control data.

 

The left part of the slide shows a snapshot taken from the ongoing measurement. A video of the experiment is stored and is available evaluation later on. The visual playback observation helps to identify any artifacts. The right part of the slide displays a diagram of the repeat determination of the softening point. The steeper the slope of the curve, the lower the viscosity. The slope indicates the flow speed.

 

Slide 27: Summary 1

The table lists the main events and properties that can be used to characterize petrochemical materials and the thermal analysis techniques recommended for their analyses. A red box denotes the recommended technique; a blue circle indicates that the technique can also be used as an alternative.

 

The most important effects that can be analyzed by DSC are the glass transition, melting and crystallization behavior, transition and reaction enthalpies, and thermal stability.

TGA is normally used to study compositional analysis, thermal stability and decomposition, evaporation and desorption behavior.

TOA is the method of choice for characterizing optical properties such as changes in morphology and cloud point effects.

The main applications of DP are the dropping and softening points for material characterization.

 

Slide 28: Summary 2

This slide summarizes the temperature ranges of the METTLER TOLEDO DSC, TGA, TOA, and DP instruments.

 

In general, DSC experiments are performed at temperatures between minus one hundred and fifty degrees Celsius (–150 °C) and plus seven hundred degrees (700 °C). If special equipment or accessories are used, the temperature ranges, and heating and cooling rates may be different.

TGA measurements normally begin at room temperature. The maximum possible temperature is about sixteen hundred degrees (1600 °C). A combination of different furnace sizes and sensors is available. In addition to automatic operation, the instrument can be connected to vacuum, sorption, FTIR and mass spectrometer systems.

TOA experiments can be performed between minus sixty degrees (–60 °C) and plus three hundred and seventy five degrees (375 °C). This depends on the particular system used. Several modes of operation are available depending on the information required.

DP samples are measured in the range between minus twenty (–20 °C) to plus four hundred degrees (400 °C).

 

Slide 29: For More Information on Petrochemicals

Finally, I would like to draw your attention to information about the analysis of petrochemicals that you can download from the Internet.

METTLER TOLEDO publishes articles on thermal analysis and applications from different fields twice a year in UserCom, the well-known METTLER TOLEDO biannual technical customer magazine. Back issues can be downloaded from www.mt.com/ta-usercoms.

 

A large collection of applications can be found in the “Thermal Analysis in Practice” and other specific handbooks.

 

Slide 30: For more information on Thermal Analysis

In addition, information about webinars, application handbooks, or of a more general nature can be downloaded from the Internet addresses given on this slide.

 

Slide 31: Thank You

This concludes my presentation on the thermal analysis of petrochemicals. Thank you very much for your interest and attention.

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