Study On The Degradation Of Waste PET And The Preparation And Performance Of Degradation Products Modified PC

Polycarbonate(PC)is a polymer material with excellent product transparency,dimensional stability,mechanical properties,weather and heat resistance.It has a great application in high-tech fields such as aerospace,electronic and electrical areas,automotive machinery and communication industry.With the development of science and technology,higher requirements are put forward for materials in the new era.Materials are developing in the direction of functionalization and safety,light weight,high performance and low cost.Due to the poor wear resistance of PC,it is easy to cause scratches,the melt viscosity is too sticky to cause processing difficulties.In addition,the internal residual stress after when the fluid is cooled is large.The product has high notch sensitivity and is prone to stress cracking,which seriously affects the service life of the workpiece.Improving the fluidity of PC through polymer blending is currently an important direction to achieve high fluidity of PC.This modification method not only combines the excellent performance of PC in all aspects,but also gives polycarbonate good processing fluidity has become one of the research hotspots in enhancing the fluidity of PC materials in recent years.In this research,waste polyethylene terephthalate(PET)plastic bottles are used as raw materials,ethylene glycol(EG)is used as a solvent to chemically degrade PET,and the degradation products are used as additives to mix with PC to prepare PC /PET degradation product composite materials,the effects of the feed ratio of PET and EG and the content of degradation products in different degradation reactions on the mechanical properties,melt fluidity and thermal stability of the composite materials were studied.Specifically,the main research content of this article includes the following three aspects:(1)Using waste PET plastic bottles as raw materials,EG as the reaction solvent,and zinc acetate as the catalyst,alcoholysis reaction is carried out by heating to near the boiling point of EG.The mass ratio of PET and EG is 1:2,1:3,1:4,respectively.To explore the conversion rate of PET in the case of different mass ratios of PET and EG.The degradation products were characterized by FT-IR,DSC and TG,and the effects of reaction temperature,PET and EG the mass ratio on the conversion rate of PET were studied.The experiment results show that the conversion rate of PET is 92.7%,93.8%,and 96.4% when reacted at 195? for 3 hours and the mass ratio of PET to EG is 1:2,1:3,and 1:4.That is to say,under the same reaction conditions,the more EG added and the higher the conversion rate of PET.(2)PC/PET degradation product composite material system: This experiment aims to improve the fluidity of PC.Using PC as the matrix material and adding degradation products that obtained under different degradation systems to PC.The effect of different content(0-8%)of degradation product on the mechanical properties,thermal stability,melt flow rate and dynamic mechanical properties of PC/PET degradation product composites was studied.Among them,the tensile strength of composite materials is decreasing with the increase of the content of degradation products;the impact strength shows a trend of first increasing and then decreasing.To the composite materials corresponding to the degradation products of the degradation system PET and EG mass ratios of 1:2,1:3,and 1:4,when the content of the degradation product is 4%,the impact strength reaches the maximum.Compared with pure PC,the impact strength increased by 4.02%,6.93%,8.25% and the tensile strength decreased by 4.73%,3.88%,and 11.8%,respectively.Melt mass-flow rate increases with the grow in the content of degradation products.The smaller the mass ratio of PET to EG in the degradation system,the greater the melt mass-flow rate of the composite material obtained from the corresponding degradation products.That is,corresponding to the degradation products obtained from the degradation system with the mass ratio of PET and EG of 1:2,1:3,and 1:4,when the content of the degradation product is 8%,the melt mass-flow rate of the composite material increases by 105.39%,123.4% and 167.13%,respectively.From the perspective of various properties,the composite material has the best comprehensive performance when the content of degradation products is 4%.(3)PC/GMA/PET degradation product composite material system: The addition of a single degradation product can lead to a sharp decline in the mechanical properties of the PC/PET degradation product composite material.Therefore,this experiment uses PC as the matrix material,adding 0-8% degradation products and 4% GMA as chemical additive to effectively improve PC fluidity,but the mechanical properties remain unchanged.Studies have demonstrated that when the degradation products and GMA are added at 4%,the tensile strength of the PC/GMA/PET degradation product composites is increased by 6.07%,5.84%,and 13.37%compared with the composite without GMA.Impact strength increased by 8.32%,7.63%,8.7% respectively.The melt flow rate decreased slightly.However,compared with pure PC,the melt mass-flow rate of the composite material still increased by 113.4%,118.65%,and 137.62%,respectively.It shows that the introduction of GMA can effectively improve the mechanical properties and solution fluidity of composite materials.