Laboratory Simulation And Representation Of PTT Filament Yarn Shape Memory Character

PTT fiber is formed from terephthalic acid (PTA) and 1, 3 - propanediol (PDO) by polycondensation. There are three methylene in its basic macromolecules chain section, and this structure will have a"Efect of odd carbon", the molecular chain which has three methylene would be bending easily, rotating the formation of"Z-type". PTT macromolecular chain has the same elastic deformation as spring in virtue of"Efect of odd carbon", and the molecular conformation has not changed,and then return to original shape when external force disappeares, conformational change is completely reversible, as a result, PTT fiber has a good shape memory characteristics.In this paper, PTT fibers are up-to-date on the current international development of new polymer materials, and predicted one of the most important new type of fiber in the 21st century. Through the establishment of ways for PTT filament yarn shape memory characteristics of laboratory simulations, to study the PTT filament yarn shape memory function of the conditions of implementation, and to determine the reasonable process parameters by experiments.Through the varying degrees of torsional deformation on PTT filament yarn, giving a different twist yarn deformation, receiving the changes of length of yarn at the deformation in the process of reversing, with the reverse deformation increased, PTT chief silk yarn twist shrinkage gradually increasing to the high-twist zone, the reverse of PTT filament yarn is more clearly in the hard twist, at the same time due to contraction of the yarn formed braided knot, in order to prevent the "braided knot"in hard twist, PTT filament yarn torsional deformation should be controlled below 2200 twist/m is more appropriate.Through the heat-setting to the torsional deformation of the yarn,researching the effection on the PTT filament yarn shape memory characteristics by the different torsion and heat-setting temperature, founding that with the reverse deformation increased, the elastic recovery rate of acute increased and is tabled in 1800 twist/m, Therefore, to reverse the excessive deformation of the elastic yarn enhance has no practical significance; Heat setting temperature on the acute elastic recovery rate has a significant impact, especially after 160℃hot stereotypes of PTT filament yarn, the elastic recovery rate of acute test results is higher than other samples, and the smallest magnitude of changes, when stereotyping in this temperature, PTT filament yarn in the fiber morphology relatively is stable, and achieving good effects of stereotypes. In this paper: under the experimental conditions of the reverse of 1800twist/m and heat-setting temperature of 155℃, PTT filament yarns obtain a better shape memory effect.Through the heat-setting to the torsional deformation of the yarn, researching the effection on the PTT filament yarn twist effect by the different torsion and heat-setting temperature, with the reverse deformation increased, shrinkage rate of boiling water of PTT filament yarn is gradually increased and the ability of restore its shape is also increased, when the reverse deformation reaches a certain degree, the shrinkage rate of boiling water is maximum; Heat-setting temperature to boiling water shrinkage rate also has a significant impact, with the heat setting temperature increased, boiling water shrinkage rate of PTT filament yarn showed a downward trend.The change of elastic recovery rate of yarn were studied through different temperatures of heat-setting, The result of the experiment have showed that different temperatures of heat setting can improve the elastic recovery rate of PTT fiber, and the rate is higher than non-heat-setting, the elastic recovery rate of PTT fiber after the heat-setting have an upward trend with the higher temperature. Stretching more than 160℃in the heat setting, elastic recovery rate is over 90%,tensile fiber internal heat-setting in higher temperature will help create a greater and complete crystal, so that the internal structure of fibers is better.This perfct structure will limit the relaxation among amorphous districti molecular chain of the fiber, and it can improve ability of flexibility in recovery so that improve its flexibility in recovery. In the contrast,with the low temperature heating treatment, fiber macromolecules segment is not active enough, the internal structure is damaged easily by imposed tension , with the occurrence of irreversible deformation,and the elastic recovery rates of PTT fiber enhance much less. In order to maximize and optimize the maintenance of high elastic fibers can respond to stereotypes fiber tensile conditions of temperature and strictly controlled.Through infrared spectroscopy, X-ray diffraction analysis, DSC analysis,the PTT fiber structure was done in-depth study, The result of the experiment have showed that the fiber molecular group is not changed and a new group is not generated after the treatment in PTT yarn at different temperatures. With the temperature increasing, there is a trend of expansion in the the district of the crystallization, the proportion of area of crystallization is increasing while the glass transition temperature increases, but the melting temperature has a little changed.