Alcoholysis And Polymerization Of The Polyester-cotton Fabric And Its Co-polymerization Modification

Polyester(PET fiber)has been widely used in clothing and home textile areas for its excellent physical and chemical properties,such as high strength,good dimension stability,corrosion resistance and so on.As the largest species of the chemical fiber industry,polyester has a massive usage but with only less than 5 % of them has been recycled and reused,most of the used polyester fabrics were processed by burning or landfill which not only causes pollution to the environment but also takes up a lot of land resources,this is bad for the sustainable development of the social environment.So the recycle and reuse of the polyester textile is of great importance,among the polyester textiles,polyester-cotton fabrics have both the advantages of the polyester and cotton,which makes it the the largest part of the polyester textiles,so the reuse of the polyester-cotton fabric is paramount.The research reports of using ethylene glycol to recycle polyester-cotton fabric aren't new,most of the researchers are focusing on only one specific polyester-cotton ratio fabric,but the polyester-cotton fabrics on the market are not merely only one polyester-cotton ratio,and for the alcoholysis product BHET,seldom did any researchers make a step forward to polymerization.To solve the problemsabove,this thesisstudiedthe alcoholysis technology of two kinds of polyester-cotton fabrics which have different polyester-cotton ratio,the difference between recycled polyester(polymerized by BHET)and ordinary polyester(prepared by PTA and EG)has also been studied,the studies are aiming at offering significant guidanceto the industrialization of the recycling of the polyester-cotton through alcoholysis.What's more,by using BHET,thisthesis prepared and characterized a new type of low melting polyester which offers a new way to reuse BHET.The main research contentsare as follows:(1)Two kinds of PET-cotton fabrics,namely 80/20 and 45/55 PET-cotton ratio,have been studied to determine its optimum EG alcoholysis technology.By changing single factor,such as reaction time,amount of catalyst and solid-to-liquid ratio,the optimum alcoholysis condition of the two fabrics has been determined respectively:(1)80/20 PET-cotton ratio fabric: reaction time is 3h,the amount of catalyst is 0.2% of PET,solid-to-liquid ratio is 1:6;(2)45/55 PET-cotton ratio fabric:reaction time is 3h,the amount of catalyst is 0.2% of PET,solid-to-liquid ratio is 1:4.(2)The PET that repolymerized of alchoholysis product has been compared with ordinary polyester,except a little decrease of melting point and viscosity and mechanical properties,it shows no apparent difference of IR,1H-NMR,TG test results from ordinary PET,besides,the color of it is a little darker than ordinary PET which may to some extent affect its application.(3)Four kinds of low melting polyester have been synthesized by copolymerization of pentamethylene terephthalate(BHPT)and BHET at the molar ratio of 1:4,1:6,1:8 and 1:10,DSC test result shows that the addition of BHPT can indeed lower the melting point of the polyester,the melting point gradually reduce with the increase of its addition amount.One of the low melting polyester that synthesized by BHPT and BHET at the ratio of 1:4 has a melting point of 190.79 °C,shows a sharp decrease of the melting point at 77 °C compared with 267 °C,the melting point of ordinary polyester.(4)The Kc values that obtained from the nonisothermal crystallization kinetics of the four kinds of low melting polyester analyzed by Jeziomy method indicate that at the same sample,Kc value increase with the increase of the cooling rate which also means that crystallization rate increase too.The a and F(T)values of the lines obtained from he nonisothermal crystallization kinetics of the four kinds of low melting polyester analyzed by Mo method indicate that to reach a higher crystallinity,a fast cooling rate is required.ln? and lnt shows a good linear relationship which means that compare with J method,Mo method is better to study the nonisothermal crystallization kinetics of the PET-co-PPT system.(5)The mechanical properties of the fiber spun from the low melting polyester show that,for the same sample,with the increase of the draw ratio,elongation gradually decrease while the breaking strength gradually increase;Different samples at the same draw ratio,with the increase of the amount of the BHPT,the breaking strength gradually decrease.