Responsible: Rafael A. García Muñoz (General Coordinator). Carlos Dominguez (LATEP Director) Address: Departmental Building I. Labs. 247 and 250. C/Tulipán s/n Móstoles 28933 Department: Chemical and Environmental Technology and Chemical Engineering Contact: Web: www.latep.es |
Quality certificate: ISO 9001: 2015
Scope: Polymeric Materials Characterization Tests.
Certificate number: ES103762-1
Carlos Domínguez Vizcaya (LATEP Director)
Email:
Phone 914 887600
Fax 914 887068
Rafael A. García Muñoz (LATEP General Coordinator)
Email:
Phone 914 887086
Fax 914 887068
Essays/Services offered
LATEP has a wide catalog of characterization tests and analysis of polymeric materials following both national and international regulations. LATEP performs the following analyzes and characterization tests:
Area of thermal properties, rheology and basic properties
Thermal analysis by difference scanning calorimetry (DSC)
Differential Scanning Calorimetry is a thermoanalytical technique that measures the heat flow between a sample and a reference to maintain both at the same temperature when the system is subjected to a controlled temperature program. Through the DSC technique, chemical reactions (thermal degradation, oxidation processes), first-order transitions (melting and crystallization processes) and glass transitions that may occur in the sample under certain analysis conditions can be evaluated. The analysis method is described in the ISO 11357 standard, the main methods carried out being:
Melting and crystallization processes (ISO 11357-3)
Glass transitions (ISO 11357-2)
Oxidation induction time(ISO 11357-6)
Determination of specific heat (ISO 11357-4)
Thermogravimetric analysis of polymers (TGA)
Thermogravimetric analysis through the weight variation curve (TGA) and its first derivative (DTGA) evaluates the weight loss of a sample when it is subjected to a temperature ramp, generally up to its decomposition temperature. Most of the TGA curves present weight loss whose origin is in chemical reactions (decomposition and separation of crystallization water, combustion, reduction of metal oxides) and physical transformations (evaporation, vaporization, sublimation, desorption, drying), although exceptionally weight gains may occur (reaction with gaseous components of the purge gas with formation of non-volatile compounds, adsorption of gaseous products in the samples).
Flexural temperature under load (HDT)
The bending temperature under load (HDT) is defined as the temperature at which a prismatic specimen made of a plastic material, rigid at room temperature, suffers a certain value of deformation under a certain load (0.45, 1.8 or 8.0 MPa) and as a consequence of a programmed rise in temperature (50 or 120 °C/hour). This method is applicable to rigid materials at room temperature. The test procedure is described in ISO 75 and ASTM D648 standards.
vicat softening temperature
The VICAT softening temperature is defined as the temperature at which a flat point needle will penetrate 1 mm inside a flat test piece of rigid plastic material at room temperature under certain load conditions (10 or 50 N) and speed of movement. heating (50 or 120 ºC/hour). The conditions for the analysis are described in ISO 306 and ASTM D1525.
Melt Flow Index Determination
The fluidity index is based on the measurement of the number of grams of polymers that, under certain conditions of stress and temperature, flow through a nozzle with a normalized internal diameter (2.095 mm). The melt index value will be clearly influenced by the physical properties and molecular structure of the polymer (molecular weight, distribution width, branching, etc.). The value of the flow index together with the analysis of possible distortions of the melt at the outlet of the nozzle will determine the method of processing the polymer. The test procedure is described in the ISO 1133 standard.
capillary rheometry
Through capillary rheometry, the rheological behavior of polymeric materials in the molten state can be studied. The material is forced to flow through a capillary of standardized dimensions, determining the functional dependence between the flow rate and the pressure drop due to friction. Through capillary rheometry, the flow curve of the polymeric material under study can be determined. These tests are carried out outside the limit of linear viscoelasticity and are capable of simulating the real conditions that the polymer undergoes during processing. The conditions for the analysis are described in the ISO 11443 standard.
dynamic rheometry
Through dynamic torsional rheometry, the rheological behavior of polymeric materials in the molten state can be studied. Unlike capillary rheometry, in this equipment it is possible to work within the range of linear viscoelasticity. In this case, the material is introduced into the measurement system, where the upper element performs torsional oscillatory movements, exerting a sinusoidally varying shear stress on the sample. Viscoelastic functions are obtained from the phase difference recorded between the deformation that has been induced and the response of the material. The test conditions to determine the dynamomechanical properties are described in the ISO 6721 standard. This equipment also allows flow tests and creep experiments to be carried out.
Fourier transform infrared spectroscopy
Infrared spectroscopy is an important tool for the identification of a polymer through the observation of its vibrational spectrum after its interaction with infrared radiation. The vibration frequency will depend on the chemical nature of the atoms involved in the vibration as well as the type of vibration (tension or bending). The infrared radiation zone covers radiation with wavelengths between 1,0 mm and 714 nm (10-4000 cm-1), although the most used in practice corresponds to the mid-infrared, between 2,5 and 20,5 μm. (4000-400 cm-1).
Density determination
The density of a material is a basic physical characteristic that will be directly related to its physical properties and final application. Among the existing methods to determine density at LATEP is the gradient column method, prepared with ethanol and water solutions and which measures densities between 0.7900 and 1.0000 g/cc. On the other hand, LATEP has a hydrostatic balance to evaluate density following the immersion method, which is based on determining the density of the polymer by first measuring its real weight in air and then its apparent weight submerged in water or ethanol.
Mechanical properties area
tensile properties
The tensile test is probably the most widely used test to mechanically characterize a material. The basis of the test consists of stretching a specimen from its ends until it breaks, continuously recording the applied force and the elongation produced. From these two magnitudes, the characteristic stress-strain curve of the mechanical behavior of each material can be determined. The basic parameters to be determined are the modulus of elasticity, stress and strain at the yield point (if any) and the strength and elongation at break.
Flexural properties
Flexural tests are primarily used as a measure of stiffness. This test is almost as common in hard polymeric materials as the tensile test, and has the advantages of simplifying the machining of the specimens and avoiding the problems associated with the use of clamps. The most important parameter obtained from a bending test is the modulus of elasticity (also called bending modulus).
Impact resistence
In impact resistance tests, a sudden high-speed stress is applied to the specimens. The usefulness of this type of test arises from the fact that impacts are common occurrences in the service life of materials, hence methodologies have been developed to determine the resistance that materials will have under these circumstances. Two different types of pendulum-based impact tests are available at LATEP: the Charpy impact and the Izod impact. In both cases, it is possible to use smooth or notched prismatic geometry test pieces, on which the energy absorbed in the breakage of the test piece is determined.
Dynamomechanical properties in polymers
Dynamomechanical analysis is one of the most widely used tools for studying the viscoelastic properties of polymers by measuring their elastic modulus and their damping after applying a sinusoidal stress on the specimens. The elastic modulus of the material is determined from the relationship between the amplitude of the oscillation and the force, while the damping coefficient of the polymer is determined from the phase difference between force and displacement. The variation of the viscoelastic properties of materials with temperature allows identifying the different transitions that occur in the material.
Determination of hardness
The hardness of a material is characterized by the resistance it opposes to being penetrated by a hard body of defined geometry, its value depending on the modulus of elasticity and the viscoelastic properties of the material. Depending on the type of penetrator, load used and the speed of application of the same, the hardness test receives different names. LATEP performs Rockwell and Shore hardness tests (scales A and D). Rockwell hardness tests employ a diamond pyramid indenter. From the measured depth of the indentation, the hardness of the material is determined directly on a dial. For Shore hardness, the most common in polymeric materials, a frustoconical indenter is used, and a force of 10 N is applied in Shore A and 50 N in Shore D for the harder polymeric grades.
Dissolution properties area
Determination of molecular weights in polymers: Gel permeation chromatography (GPC) method
A constant flow of solvent draws a polymer solution through a series of high-temperature thermostatted columns in which the polymer chains are separated according to their size. Subsequent analysis using a refractive index detector and a viscosity detector allows the amount of polymer present to be quantified as a function of retention time. A previous calibration (universal calibration) relates said retention time to the molecular mass. In this way the distribution of molecular masses is determined, and from it fundamental magnitudes for polymers such as average molecular masses and polydispersity are calculated.
Determination of molecular weights in polymers: Multi-angle light scattering method (GPC-MALS)
The joint use of gel permeation chromatography and light scattering techniques makes it possible to determine absolute molecular weights of polymers (without the need for prior calibration), the mean square radius of gyration, which gives us an idea of the size of the polymer, and the value of the second virial coefficient, which gives us an idea of the conformation of the polymer in solution.
Analytical temperature rising elution fractionation (TREF)
In semi-crystalline polymers, the chemical composition distribution (CCD) together with the molecular weight distribution will determine the microstructure of the polymer. In polyolefins, the presence, content and distribution of side chains will largely determine their properties, and their prior structural characterization is critical. In the TREF technique, a first cooling stage is carried out in solution on an inert support, for the fractionation of the polymer according to its crystallization capacity. In a second stage, elution stage, the temperature will be increased and flow will be passed over the fractionation column so that the polymer fractions elute over time according to their crystallization capacity.
Fractionation by crystallization temperature analysis (CRYSTAF)
The CRYSTAF technique seeks to quickly determine the chemical composition of the polymer (DCC). In the CRYSTAF technique, unlike TREF, the analysis consists of a single stage, in which the continuous crystallization of a polymer chain is carried out from a dilute solution. The analysis is performed by measuring the concentration of the polymer in solution during crystallization as the temperature is lowered. The analysis will be the measurement of the concentration of the polymer that remains dissolved in the solution at each temperature.
Preparative fractionation by composition
The preparative fractionation by composition will allow the physical separation of the different families that determine the chemical composition distribution of the polymer according to its crystallization capacity. This will allow each of these families to be available for subsequent characterization of each of them through different analytical techniques such as GPC, TREF, CRYSTAF, NMR, DSC, TGA, etc.
Environmental fracture resistance area
Environmental Stress Crack Resistance (ESCR)
The ESCR test is a specific test for polyethylenes and consists of evaluating their resistance to cracking when the material is subjected to environmental stress. Polyethylene resins are highly resistant to most chemicals and solvents in the absence of stress. However, many polyethylenes show cracking when exposed to the same chemical environment under polyaxial stresses. The ESCR test is described in the ASTM D1693 standard, where a polyethylene plate to which a notch has previously been introduced and has been bent in order to increase the stress concentration in the region of the notch is subjected to the action of a surface active agent at a temperature of generally 50 °C. The test consists of evaluating the time it takes for a crack to grow in the sample.
PENT test: Resistance to slow crack growth process in polyethylene
The PENT test (Pennsylvania Notch Tensile test) is exclusive to polyethylenes that are going to be used to manufacture pipes for conveying water or gas. The test determines the resistance to slow crack growth of the material. In the test, described in the ASTM F1473 and ISO 16241 standards, a sample in the shape of a rectangular prism, to which three coplanar notches have previously been introduced, is subjected to an axial stress perpendicular to the plane of the notch at a temperature of 80°C After a certain period of time, a crack will originate in the material that will grow inside. The PENT test determines the time at which the final failure of the specimen occurs.
Resistance to ozone cracking
The ozone resistance test evaluates the resistance to ozone cracking in rubber samples. Ozone generally attacks rubber by oxidizing and breaking the double bonds following an oxidative cleavage reaction that leads to polymer degradation. To evaluate the resistance, an ozone chamber is used in which a concentration of generally 50 or 200 ppcm is generated at a temperature of 40 °C. Generally, rubber specimens to which some type of initial deformation has been introduced to favor the action of ozone on the sample are evaluated. By visual inspection, the evolution of the state of the material over time and the possible appearance of cracks are determined.
Climatic chamber by Xenon lamp
Equipment to simulate exposure to the elements under laboratory conditions by means of radiation by Xenon lamp and the adjustment of the desired humidity and temperature. The equipment also allows cycles to be carried out that simulate the real conditions to which the material will be subjected.
Sample preparation area
Homogenization in laboratory rollers
Some materials such as polyethylene, propylene copolymers and some thermoplastic rubbers are often compression molded in order to obtain a plate of standardized thickness that allows the necessary characterization tests to be carried out to determine their properties. For this, a calendering process is previously carried out on laboratory rollers, in which the prior homogenization and compaction of the original material (generally pellets or flakes) is sought, as well as its prior mixing with antioxidants and antidegradants.
compression molding
After the homogenization process, the preform obtained is introduced inside a mold and in a hydraulic press with hot plates, the compression molding process is carried out at a certain pressure and temperature (always above its melting temperature). ). After a certain time at the molding temperature and pressure, a cooling ramp is applied (generally 15 ºC/min) to room temperature. Good control of the cooling ramp will determine the controlled crystallization of the material, which will directly influence its subsequent characterization.
Specimen machining
To obtain standardized specimens for testing a previously molded plate, LATEP uses a robotic milling machine with triaxial control that allows any previously designed specimen to be reproduced on the compression molded plate whose dimensions are in accordance with the corresponding regulations.
Specimen notching
Some tests require the incorporation of controlled imperfections in the material that imply a stress concentration point. These notches must be introduced in a very controlled manner as regards their geometry (angle, radius, etc.) and manner of incorporation (notch speed).
Our Team
- Rafael A. García Muñoz (LATEP General Coordinator)
- Carlos Domínguez Vizcaya (LATEP Director)
- Nuria Robledo Álvaro (Technical Manager)
- Verónica Liébana Baldomero (Head of Quality and Technical Specialist)
- Silvia Melero Hernández (Technical Specialist)
- Cesar Pedroche Rodríguez (Technical Specialist)
- Rafael Juan Rodríguez (Technologist)
- Miguel San Martín González (Technologist)
- María del Pilar González Jiménez (Laboratory Technician)
- Patricia Bartolomé Moreno (Laboratory Technician)
- Jaime Chemrouan Zegaf (Administrative)
Available equipment
Area of thermal properties, rheology and basic properties
- DSC Mettler 822e High Sensitivity Differential Scanning Calorimeter, which can work in a temperature range between -150 and 500 °C.
- Mettler Toledo TGA/DSC1 Thermogravimetric Analyzer that operates from room temperature to 1100 °C.
- HDT / VICAT 6 INSTRON/CEAST stations which operate from room temperature to 300 °C.
- INSTRON/CEAST plastometer for melt index determination that can operate between 23-400 °C.
- Gottfert robotic plastometer for determination of flow rate.
- TA Instruments DHR-2 torsion rheometer with angular velocity control between 0 and 300 rad/s, equipped with a furnace to work between 25 and 600ºC.
- Malvern Instruments capillary rheometer, Rosand RH7. Temperature range: 25 - 400 °C and extrusion speed up to 500 mm/min.
- Varian Excalibur 3100 FT-IR spectrophotometer that can operate in transmission mode or attenuated total reflectance (ATR) mode.
- Gradient column for density determination in polymers.
- Hydrostatic balance for the determination of density in polymers.
Mechanical properties area
- INSTRON 5565 5 kN universal testing machine with temperature chamber for tests from -100 to 360 °C.
- MTS Alliance 5 kN universal testing machine.
- MTS Insight 30 kN universal testing machine.
- INSTRON/CEAST instrumented impact pendulum with equipment to perform tests from -70 to 130 °C.
- DMA Q800 dynamomechanical analyzer (TA Instruments) capable of working in a frequency range from 0.01 to 200 Hz and temperatures from -150 to 600 °C.
- Durometers for Shore hardness.
- Durometer for Rockwell hardness.
Dissolution properties area
- Waters Alliance2000 high temperature GPC.
- GPC High Temperature Polymer Char GPC-IR5.
- DAWN EOS MALS detector (Wyatt Technology).
- TREF-CRYSTAF analytical Polymer Char (model 200+) (2 kits).
- TREF Preparative Polymer Char PREPmc2 for preparative fractionation of polymers by composition or by molecular weight.
Environmental fracture resistance area
- 12-station PENT test equipment (2 equipment).
- Equipment for PENT test and COD curve determination.
- HAMPDEM 2000AM ozone chamber, capable of generating a controlled ozone concentration of up to 200 ppcm.
- Atlas Ci4000 Weather-Ometer climate chamber.
Sample preparation area
- IQAP-LAP laboratory rollers (23 – 400ºC).
- Collin hot plate hydraulic presses (23 - 250ºC) with cold group for cooling ramp control in accordance with international regulations.
- Hydraulic presses with hot plates IQAP-LAP (23 - 250ºC) with cold group to control the cooling ramp in accordance with international regulations.
- INSTRON/CEAST robotic milling machine for specimens.
- INSTRON/CEAST specimen notching machine.
- BATY profile projector for geometric verification of specimens.
Certification/Accreditation of the quality system
LATEP is a certified laboratory according to standard UNE-EN ISO 9001: 2015 for performing polymeric material characterization tests (certificate number ES128405-1). It should be noted that for the certification, LATEP has also followed the criteria required by the UNE-EN ISO 17025 standard for the accreditation of testing laboratories.
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