Study On The Recycling Processes Of The Post-Consumer Polyester Uniform Fabrics

With the developing of China's textile industry, the output of the polyester textiles is increasing. As the result, the storage of post-consumer PET fabrics such as uniforms and household textiles are increasing. The recycling of post-consumer polyester fabrics are, on one hand, conducive to the reduction of the crude oil consumption, and on the other hand, to the environment protection. In this work, the glycolysis, re-polymerization and spinning of post-consumer PLA uniforms were studied to explore the optimal processes for the recycling of post-consumer polyester fabrics. Therefore, the research on the recycling of the polyester uniform fabrics is of great theoretical and practical significances.Firstly, in this work, the influence of the PET of different macroscopic shape on the glycolysis behavior was studied using ethylene glycol (EG) as degradation agent. The parameters such as catalyst, temperature, reaction time and MPET/MEG ratio were changed and the glycolysis products were tested using DSC, FTIR and 1H NMR.The results showed that the glycolytic degree was increased with the increase of reaction time, temperature and the mass ratio of PET to EG. Their glycolysis speed is in an order of polyester/cotton blend uniform>bottle>polyester uniform>melt extrusion product>virgin PET chips. The glycolysis yield:virgin PET chips> melt extrusion product>bottle>polyester uniform> polyester/cotton blend uniform and the optimal reaction condition was 1hr,190? and MPET/MEG=1:4. The results of DSC,FTIR and 1H NMR showed that the glycolysis product was BHET monomer and the L value (whiteness) of glycolysis products was in an order of:virgin PET chips>bottle> polyester/cotton blend uniform> melt extrusion product> polyester uniform.The recycled PET were prepared with a so-called partial degradation plus re-polymerization process using thermally condensed uniform and EG as raw materials. The effect of MEG/MPET ratio on the intrinsic viscosity, polydispersity index and thermal properties were studied. The relationship between shear rate and shear stress and apparent viscosity were studied using Malvern RH7 capillary rheogeniometer. The activation energy of the viscous flow and non-Newtonian index of different recycled PET were tested. The corresponding fibers were prepared by a lab-scale melt spinning and pilot-spinning machine. The crystallization and mechanical properties were studied.The results showed that partial-degradation (PD) of the post-consumer polyester uniform fabrics was realized by adding EG with an amount less than required for complete degradation. The intrinsic viscosity (?) of the recycled PET obtained using the above PD process followed by a re-polymerization process was found greater than 0.65dl/g which is the standard ? for making polyester fiber. Similar to the virgin PET, the recycled PET melts showed a non-Newtonian fluid behavior. The apparent viscosity of recycled PET melt was greater than that of the virgin PET at same temperature and shear rate. The activation energy of the viscous flow of different recycled PET were different and were all greater than that of the virgin PET which suggested a different process in the fiber spinning stage. The activation energy of the viscous flow could reach 246.1KJ/mol. The recycled PET have good spinnability and the cross-section and longitudinal surface of recycled PET fibers appeared to be smooth, dense and no obvious structural defects. The breaking strength and crystallinity of the recycled PET fibers were 3.58 cN·dtex-1 and 32.5% respectively when the mass ratio of EG:PET was 1:8. The intrinsic viscosity of recycled PET which produced by pilotscale experiment were 0.63dl/g. The mechanical properties of the corresponding fibers were lower than required for making polyester fibers for apparel application.