Using standard test procedure and conditions to perform MFI test on plastic granules is the best way to determine the physical as well as chemical properties of the material. Presto Stantest understands the need for measuring MFI of polymer granules and offers a high-quality Melt Flow Index Tester. The testing instrument is ergonomically designed keeping in mind the certain national and international standard test methods like ASTM D1238 – 13, ASTM D2839 – 10, IS 2530 (1963), IS 10810- 1984 (Part 23), IS 2267 – 1995, etc. The instrument is assembled using latest technology based sophisticated features such as PID controller that helps to control the temperature inside the chamber with high accuracy, a digital timer to set the test time up to 999 hours, an automatic cutter that cut the melted sample after a period of time automatically and many more.
Using highly standardized testing machine is not the only solution to compute the quality or grade of granules. To ascertain the quality, it is necessary to follow standard operating procedure. Below mentioned are some steps that help to calculate the MFI of plastics in highly appropriate manner.
Standard Operating Procedure
1. First of all turn the machine on by plugging the mains socket of the machine into a 3 pin 15 amp socket.
2. Set the SV value on the PID controller and the test duration timing on the digital timer.
3. Switch on the toggle switches from the control panel for automatic cutting of sample.
4. After setting the temperature and timer, turn the heater on by pressing the heater on the switch.
5. Wait for the reading in the PV display in the PID controller to reach the value of the SV display.
6. After the required temperature for the test has been attained, fill the barrel of the machine with the plastic granules you want to test.
7. Poke the granules with the plunger after they are inserted into the barrel to ensure close packing of the granules and eliminate the air between the granules.
8. When the granules are inserted in the barrel, there will be a slight decrease in the PV value on PID monitor. Wait for this value to again reach the SV value.
9. Once the PV and SV value are the same, place the plunger provided with the machine along with the dead weight on it into the barrel.
10. After placement of plunger, melted plastic comes out of the barrel.
11. When the time cycle on the digital timer completes, the cutter will automatically cut the sample from the barrel.
12. Weigh the melted sample using a digital balance. This weight will be used for calculating the Melt Flow Index of the sample.
The formula to Calculate MFI:
MFI = Weight of sample in grams/ 10 min.
Selection of Test Conditions
Certain test conditions need to be selected in terms of temperature and load to perform a particular type of test for a particular material type. The test condition must be chosen in such a manner that the flow rate of the material falls between 0.15 to 50 grams in 9/10 minutes.
|S. No.||Test Condition||Test Temperature (degree Celsius)||Test Load(Kg)||Recommended for|
|4.||190/0.325||190||0.325||Cellulose esters, Polyethylene|
|5.||190/1.05||190||1.05||Acetyls (copolymer & homopolymer)|
|6.||190/2.16||190||2.16||Acetyls (copolymer & homopolymer), cellulose esters, polyethylene|