Mechanical methods are mainly used to test the stickiness of cotton fibers, including hot plate test method, micro carding machine method, circulating roller method, etc.
1. Hot plate inspection method
The hot plate inspection method was pioneered by researchers from the French International Cotton and Fiber Crop Research Institute (IRCT), and the thermal detector is manufactured and sold by a French company. The detected temperature is controlled at 24°C and the relative humidity is 60%±5%. When testing, comb 2.5g cotton sample into a thin layer of cotton net on the carding machine with bare hands, or use a mechanical opener to organize it into a cotton net. Place the cotton net between two layers of aluminum foil paper, and then put it into the thermal detector. Heating is between two metal plates under pressure. After cooling, the sticky spots on the tin foil paper are clearly visible. Use a counting pen to count the number of sticky spots.
The hot plate sticky cotton tester SCT (Sticky Cotton Thermodtester) produced by Grat Company in Germany also uses this principle for testing. Use a hot plate to heat the cotton to 90°C to release the sticky substances, and cool it on a cold plate to make the sticky fibers adhere to the aluminum foil paper. Count the number of adhesion points to determine the stickiness of the cotton. The SCT test method is very similar to the phenomenon of viscosity release due to the increase in temperature and pressure of the roller during the spinning process of sticky cotton. Both have shortcomings such as small sample inspection volume, time-consuming inspection, and subjective counting of sticky cotton points.
Correlation analysis shows that the square root of the number of sticky points in thermal detection is directly related to the grade detected by the MiniCard test, with a correlation coefficient of 0.75. The International Textile Processing Federation (ITMF) recommends that international laboratories adopt the hot plate test method. The “Cotton Stickiness Test Method” formulated by the Xinjiang Import and Export Commodity Quarantine and Inspection Bureau using the SCT method was listed as a 2002 Xinjiang inspection and quarantine scientific research project and designated as the import and export cotton stickiness test method.
1. Test principle
Take 2.5g cotton sample and comb it into a thin layer of cotton net on the carding board with bare hands, or use a mechanical opener to organize it into a cotton net, and place the cotton net between two layers of aluminum foil paper , put it into the thermal detector, heat and pressurize between the two metal plates. After the hot plate has cooled down, use a counting pen to count the number of sticky points, and determine the viscosity grade of the cotton based on the number of sticky points. The viscosity is divided into 5 levels, namely no stickiness, light stickiness, medium stickiness, and severe stickiness. Sex, polarity and severe viscosity.
2. Instruments and materials
SCT cotton viscosity thermal detector, aluminum foil, mechanical opener or small carding machine.
3. Environmental control
Temperature: 24℃±1℃; relative humidity: 60%±5%.
4. Test steps
(1) Test preparation: Turn on the power of the host and preheat for 30 to 60 minutes until the green light turns on, indicating that the temperature of the heating plate has been preheated evenly. At this time, the temperature should be between 80 and 85°C. Clean the work area and place a piece of aluminum foil on the lower clamping plate, rough side up.
(2) Test method: Place the 5g cotton sample taken previously on a carding board or cotton opener and comb it into a uniform cotton net weighing about 2.5g, and then lay the cotton net flat on the pre-placed thermal inspection Place the aluminum foil on the heating plate of the instrument, and then cover the cotton mesh with a piece of aluminum foil, with the rough side facing down.
Pull out the heating plate and place it on the cotton sample. When you hear a sound after 12 seconds, lift the heating plate and slide it to the back. Use the upper pressure plate to press the cotton sample again until you hear another sound after 2 minutes. Lift the upper platen and move the aluminum foil and cotton sample together to the table. Carefully lift up the top aluminum foil, with the rough side facing down, place it on the table, turn on the counting lighting power, and count the sticky spots. Take out the lower aluminum foil and count in the same way.
5. Result Judgment
Total the sticking points on the two aluminum foils and judge the viscosity classification standard according to Table 5-6.
Two samples are tested in each batch. If the results of the two samples exceed two levels, a third sample is tested and the average of the test results is taken.
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