Study On The Recycling Of Packaging Waste PET Bottles And Its Application In Polyurethane

With the wide use of PET bottles,because of its non-biodegradability,it has caused a lot of environmental pollution.It is of social value to study the recycling of waste PET(rPET).In this paper,two methods of recovery and reuse of rPET and their applications in polyurethane are studied.The two methods are physical blending method and chemical alcoholysis method,respectively.rPET was blended with thermoplastic polyurethane elastomer(TPU)by physical method,and then modified with acidified carbon nanotubes(CNTs)to prepare CNTs/rPET/TPU composites.The effects of CNTs content on the properties of composites were analyzed by Scanning electron microscopy,X-ray diffraction,thermal and mechanical properties,rPET was alcoholized by chemical method,and acidified CNTs were added in the reaction process to prepare waterborne polyurethane(WPU)/CNTs emulsion.Transmission electron microscopy,Fourier transform infrared spectroscopy,X-ray diffraction and ultraviolet visible spectroscopy were used to prepare the emulsion.The effects of CNTs on the properties of WPU/CNTs emulsion and the influence of WPU on the dispersity of CNTs were investigated by thermal and water resistance tests.These two methods can not only recover rPET but also obtain the products with good properties through the modification of CNTs.The results show that,in physical method,the morphologies of CNTs/rPET/TPU composites show a single phase structure.The existence of good compatibility between pure TPU and rPET.The glass transition temperature of rPET/TPU composite is-29.6℃ and that of pure TPU is-36.3℃.Compared with pure TPU,the thermal stability,tensile properties and storage modulus of rPET/TPU composites are worse.With the addition of CNTs,the glass of CNTs/rPET/TPU composites increases with the increase of its content.The transition temperature decreased and the thermal stability,elastic modulus and tensile strength increased.It is concluded that the existence of interfacial adhesion between CNTs and rPET has a counteracting effect on the rigidity of rPET.In the chemical method,WPU was successfully synthesized in the experiment,and the thermal stability of the partially dispersed CNTs in the WPU matrix increased with the increase of CNTs,and then decreased,which was related to the steric resistance of CNTs.The results of water absorption test showed that CNTs could decrease the water absorption of WPU samples.When the content of CNTs was 0.3 wt%,the water absorption of the sample was 27.50%,while that of pure WPU samples was 33.59%.With the increase of CNTs content,its dispersion in WPU becomes worse.