Judgment method and test method of leather abrasion resistance1

Judgment method There are two methods for judging the leather wear resistance index, namely the end point method and the appearance change method. 1. End point method: The number of rotations required to remove 1 mm of leather is the thickness index of wear resistance, and the number of friction rotations is recorded as the wear resistance index. 2. Appearance change method: After the test sample has been rubbed for a certain number of times, observe its appearance changes, such as color change, degree of wear and other appearance changes as wear resistance indicators. New conventional test methods for leather abrasion resistance: 1. Flat abrasion method (1) Reference standard: 'GB/T 21196-2007 Determination of abrasion resistance of Martindale fabrics'. (2) Test instruments: There are many types of fabric flat grinders. At present, the Martin denier is the most used in the testing industry. Therefore, the flat grind method is often called the MARTINDALE friction tester method. (3) Test principle: The circular sample installed in the sample fixture of the Martindale abrasion tester is subjected to a Lissajous graphic plane motion and abrasive (ie standard fabric) under the specified load. friction, the specimen holder is free to rotate about its axis perpendicular to the horizontal plane. The abrasion resistance of the leather is determined according to the total number of frictions in which the sample is damaged. (4) Test method: During the test, the test sample of a certain size is in contact with the standard abrasive under the specified pressure, and the sample is moved relative to the abrasive in the Lissajous trajectory, so that the test sample is uniformly worn in multiple directions. 2. Taber abrasion resistance method (1) Reference standard: 'GB/T 2726-2005 Determination of Abrasion Resistance of Leather Physical and Mechanical Tests'. (2) Test equipment: TABER abrasion resistance testing machine (3) Test principle: pre-grind for 25 revolutions, place the tested sample on the horizontal platform of the TABER abrasion resistance testing machine and rotate, and the two grinding wheels are given a specific pressure It is optional to press on the test piece, the axis of the grinding wheel is parallel to the horizontal plane, one grinding wheel is facing outward, the other is facing inward, and all changes of the test piece are recorded within a certain period of time. (4) Test method: A sample with an outer diameter of 108 mm and an inner diameter of 8 mm was cut with a cutter. Then stick a hard sticker of the same size on the back of the sample. Place the center hole of the sample on the rubber pad of the screw, cover the gasket, and fix the sample with a compression nut. Then put the fixing ring on, and tighten the fixing ring screw with a wrench. Install two H18 grinding wheels on the support arm, each grinding wheel applies 250 to the test sample±10g force, make sure the side with the label is facing outward, make the load of the grinding wheel 500g, connect the vacuum cleaner, connect the vacuum cleaner's suction tube to the connector on the left side of the machine, and start the vacuum cleaner. Set the number of tests according to the standard, and set the rotation speed to 72 rpm. Then start the start button, start the rotation speed to 60±5 times/min of the instrument, rotate horizontally, and perform the test according to the required number of times. During the test, use a brush to remove the attachments on the surface of the sample, observe the wear condition of the test, grind the leather to the specified end point, and record the final number of revolutions. 3. STROLL abrasion method: According to ASTM D 3886-1999 'Standard test method for abrasion resistance of textile fabrics (inflated diaphragm apparatus)', the test principle of STROLL abrasion method is to place the test sample on an inflated rubber diaphragm with constant air pressure. , rub the specimen with sandpaper with the specified surface characteristics. The degree of wear of the specimens was evaluated visually after the specified number of rubs. Operation steps: Place the sample on the rubber film in a flat state, then place the sandpaper on the abrasive plate, and make the contact head connected by the sandpaper flush with the surface of the sandpaper. An air pressure of 28 kPa was then applied below the diaphragm and 454 g above the abrasive plate, ensuring that the air pressure control and the contact between the inflated sample and the loaded sandpaper were stable and balanced. Start the instrument and perform the test according to the number of rotations set by the counter. After the test, remove the sample, check and record the wear of the sample, and use a gray sample card to evaluate the color change in the test area according to GB/T 250-2008 'Textile Color Fastness Test - Gray Sample Card for Assessing Discoloration'. The comparison of test results obtained by testing different materials using the same experimental method is of little significance, but the conclusions drawn from these results are consistent. Therefore, either method can independently quantify the wear resistance of materials. In general, the material of natural leather is softer and therefore less resistant to abrasion. Coated leather has a harder texture and is not easy to wear, so it has better wear resistance.

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