Method for testing the flame retardant properties of yarns

Most of the existing textile flame retardant performance tests are carried out on fabrics, that is, the fibers are first spun into yarns, and then the yarns are woven into fabrics of certain specifications, and then the corresponding flame retardant performance test methods are used to test their flame retardant properties.When using various fibers and blended proportions to design flame-retardant textiles, and when evaluating their flame-retardant properties, they need to be made into fabrics before testing, which is time-consuming and laborious, and increases the cost.

The commonly used flame retardant test methods are vertical combustion method, 45° inclined combustion method, finite oxygen index method, etc.Among them, the vertical combustion method and the 45° inclined combustion method can only test the flame retardant of the fabric, and the finite oxygen index method can test the flame retardant of the fiber and fabric.

Problems with existing flame retardant performance test methods：

1. The vertical combustion method and the inclined combustion method can only use the fabric for flame retardant performance testing, which requires a lot of time to weave the fabric (sample), the process is long, time-consuming and laborious, and the cost is increased at the same time.

2. The finite oxygen index method can be used to characterize the ease with which fibers or fabrics are ignited, but it cannot measure the danger in the event of a fire.Studies have shown that sometimes flame-retardant materials with a high oxygen index burn more violently in a fire than materials with a low oxygen index.In the oxygen index test, the material is ignited from above, and then the flame propagates downwards. This combustion method is different from the combustion method of the material in the actual fire, and the correlation between the test results and other combustion performance test results is relatively poor.

In order to achieve the above purposes, the current technical solution is to provide a test equipment for the flame retardant properties of yarns, including a combustion test chamber. The combustion test chamber is provided with a sample clamp along the angle of 45° from the base plate of the combustion test chamber, and an igniter is provided between the sample clamp and the base plate. It is characterized in that the hollow part of the middle of the sample clamp is provided with two support blocks on the upper side, and the middle of the support block is provided with a yarn holder, and the combustion test chamber is also provided with a tension device connected to the yarn bundle to be tested during the test.Further, the distance between the yarn grippers is 200±30mm.

Specific detection steps：

1. Conduct the test under atmospheric conditions with a temperature of 10°C~30°C and a relative humidity of 15%~80%. Light the igniter and preheat it for l-3min, adjust the flame height so that the distance from the top of the igniter to the top of the flame is 45±Imm.；

Two: Use a yarn holder to clamp the yarn bundle to be tested connected to the tension device, add 2-4 twists to the yarn bundle to be tested in the direction of yarn twist, and place the sample clip of the yarn bundle to be tested in the combustion test chamber, so that the distance between the top of the igniter and the surface of the yarn bundle to be tested is 45±Imm；

Three: Use a timing device to control the ignition of the igniter to ignite the yarn bundle under test. The ignition time is 5~7s. The time from the start of the ignition to the removal of the yarn bundle under test from the combustion test chamber is controlled at 0.5-lmin, the continuous combustion and smoldering time are measured, and the sample clip is removed from the combustion test chamber. The length of the sample is directly measured when the yarn bundle under test is clamped.；

Four: Take the yarn bundle to be tested of the same sample, repeat the last step to the third step 10-12 times, and the test results are averaged.