Mechanical Physical Properties laboratory

Mechanical Physical Properties laboratory

The Laboratory of Physical and Mechanical Properties of Polymer Engineering faculty was established in 1997. This collection was created with the aim of educational and research activities for undergraduate and graduate students and has facilities such as a notching device, MFI device, Vicat & HDT device, impact test device, hood, heater stirrer, vacuum oven, and normal oven. Also, this laboratory with the aforementioned facilities is responsive to all customers from the industry and academic community.

  • Melt Flow Index (MFI) measuring device

 It is a measure of the ease of melt flow of a thermoplastic polymer. Melt flow index (MFI) unit, as the mass of molten polymer passing through a die hole) in grams with a certain diameter, length, and pressure in ten minutes at a certain temperature (polyethylene 190 degrees Celsius and polypropylene 230 degrees Celsius) Definition has been it can be defined as the melt flow index is the polymer mass in grams that comes out in ten minutes (gr/10 min) through a hole (Die) with a constant diameter and length at a constant temperature, Meanwhile, a standard weight is placed on the piston of the thrust chamber, which contains about three grams (up to 8 grams) of polymer.

The melt flow index is somewhat but not exact (inversely proportional to melt viscosity). Therefore, it decreases with the increase of the average molecular weight. A higher melt flow index indicates more fluidity at processing temperatures. This symbol is originally intended to indicate sylvanic properties as a measure of extrudability. In general, with the increase of the melt flow index, the tensile strength, tear resistance, softening temperature, and toughness of the polymer decrease.

To identify the properties of polymers, various tests are conducted in reputable laboratories, and many of these tests are time-consuming and have high costs. But in the industry, due to the need to identify the process properties of polymers faster, MFI: melt flow index is used. This index in a way indicates the density of the polymer molecule and ultimately the fluidity of the polymer melt in laboratory conditions.

The standards used for measurement are MFI ASTM D1238 and ISO 1133. The basis of the work is that the sample is placed in a cylinder under the temperature and force applied by the weight above it. Under these conditions, its melt begins to exit from the hole embedded in its bottom. Its output value is cut by an automatic cutter at certain times, and finally, all the pieces are individually measured by weight and average weight. The MFI value of the object is determined according to a formula. A schematic of this device can be seen in the figure below.

The MFI value of the product is a function of the molecular mass of the polymer. The higher the MFI value of the product, the more fluid the polymer melts and the lower the process temperature.

Note:MFI terms are synonymous with MFR (Melt flow rate).   

  • A decrease in the amount of MFI causes:
  • Increase in difficulty
  • Increased tensile strength
  • Increase in yield point strength
  • Increased creep resistance
  • Increased toughness
  • Increasing the softening temperature
  • Increased resistance to cracking stress
  • Increased chemical resistance
  • Increased molecular weight
  • Reduction of polish and gloss      
  • Decreased permeability

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  •  Softening temperature measuring device

 This device is for measuring the Vicat Softening Point and Heat Deflection Temperature of plastics. The sample is placed in the holding assembly and then the whole assembly is placed in the oil bath. And the oil temperature increases with the specified speed. For the HDT test, the temperature at which the sample bends by 0.25 mm is recorded and reported as the test result. For the VST test, the temperature at which the standard needle penetrates 1 mm into the sample is recorded and reported as the test result.

Technical Specifications:

  • 2-walled tank, inner wall of steel sheet, outer wall of blind color sheet
  • Oil bath with adjustable heating speed
  • Maximum usage temperature: 250 degrees Celsius
  • Modular design with the possibility of testing 1 to 4 samples at the same time
  • Measurement of displacement by a measuring gauge with an accuracy of 0.01 mm
  • The possibility of recording product results
  • Ability to perform 4 HDT or VST tests at the same time
  • The device is equipped with an automatic oil cooling system by circulating water in copper coils.
  • Using 2 thermocouples to measure the oil temperature around each sample
  • The possibility of connecting a nitrogen or carbon dioxide gas capsule to create a neutral environment around the oil to increase the temperature of the oil. Recording all results by computer.
  • Record all the results on a flash disk in Excel file format (Microsoft Excel).
  • HDT-Vicat device is designed according to ASTM D648, ASTM D1525, ISO306 ISO 75 standards.
  •  Impact measuring device   

This device is used to measure the impact strength of materials against sudden loads and also has a very special application in plastic industries. The SIT-20E series pendulum impact device is used to determine the impact resistance of standard brittle plastic samples, and the impact test is a suitable criterion for determining and classifying the tendency of different plastics for brittle behavior. It has also been widely used in various fields such as research and development, quality control, etc., which can be mentioned below.

  • Quality control of raw materials of all kinds of plastic products   
  • Research on composites against impact loads

 Description: According to the standard, in this device, a pendulum with a certain energy (mass, release height, and geometry) is released to hit the sample and cause it to break. After breaking, the pendulum rises to a certain height, and this height difference is the main quantity measured in the impact test, which is the energy absorbed in the break, and its equivalent energy is shown in joules on the device panel. This device has a digital output display and is also equipped with a manual tool to release the pendulum. The use of the device is very simple and the user can easily read and report the impact energy. Sharpie and Izod anvils can be installed on the device to perform the impact test by the mentioned methods. In addition, the design is based on the installation of pendulums with different capacities (such as Sharpie pendulum according to ASTM-D6110 standard with different energies of 1J, 2J, 5J, 7.5 J, 15J, 20J - Izod pendulum according to ASTM-D256 standard with energies of 1J, 2.71J, 5.5 J, 7.5J, 11J, 15J, 21.7J - Sharpie pendulum according to ISO-179 standard with energies of 2J, 5J, 15J - Tensile impact pendulum according to 13802, ISO 8256 standard with energies of 2J, 4J, 7.5 J, 15 J) which allows the user to perform the test with the desired capacities. Pendulums are designed based on the minimum distance between the center of impact of the pendulum and the line of impact. This dynamic feature eliminates all lateral forces in the bearings during the impact and all the energy of the pendulum is transferred to the sample. Using the CALIBRATION SELF option in the panel menu, without placing the sample in the device and after releasing the pendulum and performing 11 half-cycle oscillations, the following characteristics will be determined automatically:

  • The exact angle of release 
  •  Actual collision speed 
  • Frictional losses (based on 1 and 11 half cycles)
  •  Actual pendulum energy (using pendulum energy at 90 degrees 'mg' shown on each pendulum)
  • Polymer notching device 

This device is used to create accurate notches and prepare polymer impact samples, which are used for prototyping in a wide range of polymers in terms of type and size.

  • Vacuum Oven 

  The vacuum in the laboratory of physical and mechanical properties is from the Binder brand in Germany.

benefits:

  • Quick and gentle drying

  • Optimal heat transfer through large heat-conducting plates

  • Safe operation thanks to the proven safety concept

  • Also option of a complete modular system with vacuum pump and pump housing

Important features:

  • Temperature range: +9 degrees Celsius above ambient temperature up to +220 degrees Celsius

  • Controller with digital pressure and temperature display

  • Program-controlled drying monitoring with automatic ventilation at the end of the process

  •  Built-in data logger, measured values can be read in open format via USB

  • 1 aluminum expansion rack, which can be customized inert gas connection

  •  Universal access port DN 16 - for introducing external measuring devices

  • Unbreakable safety glass panel and spring

  • Large viewing window with built-in lighting option

  • Computer interface: Ethernet