Research On The Elasticity Of PTT/PET BI-Component Fiber And Fabric

The elastic mechanism of PTT(Polytrimethylene terephthalate)/PET (Polyethlene terephthalate)fiber is different with polyurethane fiber's, the former possess self-crimp elasticity which is caused by different thermal shrinkage between PTT and PET. So elastic stability and durability of PTT/PET bi-component fiber are excellent. In the meanwhile, it can be used as weft or warp directly which can improve productivity, therefore, PTT/PET bi-component fiber and its fabric attract more and more attentions in research areas and markets.There is a long history on its research for our team. The scientific research items that elastic mechanism and prediction, the develop of PTT/PET bi-component fabric have been completed. This paper that is on the base of these researches has done in-depth research on the elasticity of PTT/PET bi-component fiber and its fabric. The conclusions and results include the following four parts.Firstly, two different kinds of composite spinning components which is designed by team are chosen. The experiments of composite spinning are done with school's devices, which adopt two composite methods. One is called parallel compound or inside-plate compound which means that two kinds of polymer fluids integrate inside of plate, the other one called air compound or outside-plate which denotes that two kinds of polymer fluids integrate outside of plate. Finally, six kinds of filaments that called Z series are spun through variation of percentage content of PTT. The other one named Q series which are provided by factory.Secondly, the comparable samples are selected from Z and Q series. Then the longitudinal and crossing section morphology of samples are taken photos by scanning electron microscope and optical microscope. Fibers'morphology is observed and compared especially the unique groove character existing composite interface. The relationship between fibers'morphology and spinning conditions including compound methods, percentage content of PTT, the intrinsic viscosity of PTT and the temperature of hot plate is found out. The final conclusion is that the groove of composite fiber would be obvious and wide when the spinning condition is as follows: 50% PTT content, using air compound, larger intrinsic viscosity of PTT and lower temperature of hot plate.Thirdly, spinning technology of PTT/PET bi-component composite fiber is checked from the aspect of fabric elasticity test. The result of elasticity test does fluctuate greatly for PTT/PET bi-component composite fiber. In the meanwhile its result is not in line with its fabric's. It is necessary to check spinning technology of PTT/PET bi-component composite fiber more accurately from the aspect of fabric elasticity, which can provide guidance to the production. Firstly, two series of testing samples are weaved and tested, the one called Z fabric series, the other one called Q fabric series. Then it would be analyzed that how four main spinning conditions including different compound method, the intrinsic viscosity and percentage content of PTT and temperature of hot plate effect elasticity of fabric. Finally, fabric stretch under a specified tension would be much larger under these conditions including parallel compound, the increasing difference of the viscosity of two polymer and high temperature of hot plate. Besides, PTT content and elastic modulus ratio (m) have cross-impact on the elasticity. If the value of m is in the different range, different PTT contents have different impacts on crimp curve of fiber and elastic of fabric. Analog computation is done with the help of mathematical model of bi-components fiber's curve which is derived by Denten. Only if the value of m is small relatively, bi-component fiber whose PTT percentage content is 50% possesses the best elasticity, which corresponds with the report of some references. However, if the value of m is in the high value range relatively, with the increase of PTT content, crimp curve of fiber would drop which means the elasticity of fabric would reduce. This result makes a good explanation for unintelligible experiment phenomenon.Finally, the elastic fatigue durability between polyurethane fabric and PTT/PET bi-component fabric is made comparison according the demands of company. Three kinds of testing methods are explored out, which contain multiple reciprocating tensile method, ASTM testing method and unite method. The elastic fatigue durability for PTT/PET bi-component fabric is better than polyurethane fabric, however, the latter's fatigue durability can be improved through increasing polyurethane fiber's content. Also, fabrics whose content of wool is high have good fatigue durability. Eight kinds of fabrics in the experiment that have not accumulated lots of plastic deformations still keep good elastic resilience, although they are stretched 1000 times. So we should break the testing condition ruled by standard, such as adding load value or tensile times, in order to obviously show PTT/PET bi-component fabric better fatigue durability.