Effects Of CO₂Laser-heated Drawing On Structure And Mechanical Properties Of Poly（Ethylene Terephthalate） Filaments

In this study, poly(ethylene terephthalate)(PET) partially oriented yarns was drawnwith CO2laser as heat producer and the structure and mechanical properties of PETfilaments were studied. All of these works were aimed at putting forward a new productionprocess of PET filaments and providing theoretic support for the new production process.PET filaments were prepared by self-made CO2laser-heated drawing apparatus withPET partially oriented yarns(POY) as raw materials. According to the results, themolecular chain of PET filaments oriented better along the fiber axis and the crystallinityof PET filaments increased after heat-drawn by CO2laser-heated drawing apparatus. Themechanical properties of heat-drawn PET filaments also increased. The mechanicalproperties of heat-drawn PET filaments was good with the laser current was4.5mA, thedraw ratio was2.0and the laser current was3.0mA, the draw ratio was2.4.Nano ZnO sol with good grain size distribution was prepared with zinc acetate,sodium hydroxide and methanol as raw materials. After24hours, The average grain size ofZnO sol just increased from±20nm to±30nm. After baking10min under170℃, ZnOpowder was obtained with good crystalline structure.PET partially oriented yarns were treated by self-made ZnO sol. After treated, therewere many graniform particles spreading over the surface of PET partially oriented yarns.According to the study results, ZnO sol could lead to disorientation of PET molecular andforming paracrystal in the PET filaments. As a result, the breaking elongation of PETpartially oriented yarns increased and the breaking strength and initial modulus decreased. PET filaments were obtained by using self-made CO2laser-heated drawing apparatusto heat-drawn ZnO sol treated PET partially oriented yarns. The obtained PET filamentshad good mechanical properties. When the laser current was5.0mA and draw ratio reached2.5, the breaking strength and breaking elongation of treated PET filaments reached3.16cN/dtex and33.5%, respectively.After baking10min under170℃, the content of tie molecules arranged betweenamorphous and crystalline regions in treated PET filaments increased. At the same time,much paracrystal formed in treated PET filaments. For these two reasons, the breakingstrength and initial modulus of PET filaments increased and the breaking elongationdecreased.