The Processing, Structure And Properties Of DTY From Recycled PET Bottle

Plastic industry produces waste plastics, which have brought serious environmental andresource issues. In terms of optimizing the ecological environment, PET bottles recycling is anindustry with good prospects. In terms of utility value of recycled PET bottles, the recovery rateof waste PET bottles is up to95%. Currently, recycled PET bottle chips were used in the filedof non-woven and staple fiber, however, they havn’t been widely applied in the filed of filament.Therefore, it is very meaningful to discuss the technology of how to spun filament usingrecycled PET bottle in domestic. It will play a positive role in promoting the development of thetextile.The processing parameters, structure and properties of DTY from recycled bottles werestudied in this thesis. The main contents and conclusions of this subject are as follows：1. XRD, DSC, sound velocimeter and single fiber tensile testers were used to analyze thestructure and properties of recycled bottle flakes POY and ordinary POY.The results showed that there were differences between recycled bottle flakes POY andordinary POY: compared with ordinary POY, the Tg, Tc,Tmand crystallinity were lower; theorientation，the breaking strength, the boiling water shrinkage rate were greater, while thebreaking elongation was lower.2. To discuss the effect of various processing parameters on the structure and properties ofPET bottle chip DTY, the processing parameters of processing speed, draw ratio, texturingtemperature, heat setting temperature, overfeeding ratio and D/Y ratio were adjusted.The results showed that in a certain range, with the processing speed increased, thecrystallinity and orientation decreased, there was no significant effect on breaking strength andelongation, modulus and curly shrinkage rate dropped, and the boiling water shrinkage rate rose.With the draw ratio increased, there was no effect on crystallinity of XRD, the breakingstrength, breaking elongation and curly shrinkage rate dropped, while the orientation, modulus,and boiling water shrinkage rate increased, and the crystallinity of DSC increased after drawratio of1.60. With heat texturing temperature increased, the crystallinity increased and orientation decreased, when the texturing temperature of195℃below, the breaking strengthincreased, while the temperature was higher than195℃, the breaking strength decreased, themodulus and curly shrinkage rate rose, while the breaking elongation and boiling watershrinkage rate dropped. With heat setting temperature increased, the crystallinity andorientation both increased, while when the temperature above195℃, the crystallinity of XRDdecreased slightly, and there was no effect on tensile properties, and the curly shrinkage rate,boiling water shrinkage rate dropped. With overfeeding ratio increased, the crystallinity andorientation decreased, there was no effect on breaking strength, and the breaking elongationrose, while the modulus, curly shrinkage and boiling water shrinkage rate dropped. With D/Yratio increased, there was no significant effect on crystallinity and DTY performances, and theorientation decreased first and then increased.3. Various processing conditions such as the second stretch roll, the false-twist device, thesecond hot-box were discussed. The results showed that different conditions had differenteffects.The DTY formed specific structures of crystallization and orientation, under the stretchingof the second stretch roll, the twisting of the false-twist device and the heating effect oftemperature. Compared with the recycling bottle flakes POY, the breaking strength andmodulus of filament increased, while the strength elongation of filament decreased, the boilingwater shrinkage rate of filament dropped much. As the twisting torque of false twister offsets aportion of tensile strength, twisting prevented the crystallization and orientation of crystallineand amorphous region, which leaded to higher breaking strength and modulus, lower strengthelongation, crimp shrinkage rate and boiling water shrinkage rate of filament of draw-shapingfilaments and drawing filaments. The crystallinity of DTY and draw-shaping filamentsincreased after heat treatment in the second hot-box, while the orientation did not change, butdropped slightly. Compared with high stretch yarns, the breaking strength of DTY was higher,while the strength elongation, crimp shrinkage rate and boiling water shrinkage rate were lower.Compared with the high stretch yarn, the breaking strength of DTY was slightly higher, themodulus, breaking elongation, crimp shrinkage rate and boiling water shrinkage rate were lower,compared with the draw yarn, the breaking strength of draw-shaping filaments was slightlyhigher, the modulus, breaking elongation, crimp shrinkage rate and boiling water shrinkage rate were lower.4. XRD, DSC, sound velocimeter and single fiber tensile testers were used to analyze thestructure and properties of recycling bottle flakes DTY and ordinary DTY.The results showed that the crystallinity of ordinary DTY was higher than recycling bottleflakes DTY, while the orientation factor fsand velocity modulus E of recycling bottle flakesDTY were higher. Compared with ordinary DTY, the breaking strength, strength elongation,crimp shrinkage rate and boiling water shrinkage rate of recycling bottle flakes DTY werehigher, while the modulus was lower.5. The orthogonal test was used in this subject to determin the better process condition ofrecycling bottle flakes DTY. The optimized process conditions showed as follow: theprocessing speed was450m/min, the draw ratio was1.60, the deformation temperature was185℃, the setting temperature was165℃, the over-feed ratio was5%, the D/Y ratio was1.8,and the quality of recycling bottle flakes DTY was greatly improved after optimization.This study provides useful theoretical basis on how to optimize the process parameters ofrecycling bottle flakes DTY, and technical support on how to solve problems during thespinning and application process, and this study makes a contribution to establish and promotethe recycling and application systems of waster PET bottles, and improves the environmentquality.