Study On The Preparation Of EHDPET/NEDDP Sea-island Composite Fibers With Different Composite Ratios And Their Properties

Superfine fiber is one of differential fibers.Because of its much smaller monofilament linear density than that of ordinary fiber,the fabrics weaved with superfine are lightweight,breathable and natural with good feeling.Superfine fiber has a wide arrary of application in the field of textiles,medical treatment and public health,etc.Nowadays,Polyethylene terephthalate,PET,is often used as island component with a hydrolysis degradable polyester,EHDPET,as sea component by melt spinning to prepare composite fibers with a ratio of 70/30.However,the superfine PET component is hard to deeply dye because of its large specific surface area.Meanwhile,high content of sea component will directly increase the production cost and lead to environmental polution.Preparation of sea-island composite fibers with lower sea compoment content and good dyeing properties becomes the focus in this field.Thermal properties,molecular structures and rheological properties of EHDPET and NEDDP used as raw materials in this dissertation were studied through a series of characterization methods.Main results achieved in this paper are listed as following:The melting points of EHDPET and NEDDP are 243°C and 246°C,respectively.The weight loss temperature of NEDDP is higher than that of EHDPET,showing good thermal stability.The intrinsic viscosities of both materials are all higher than 0.7 m L/g,the data of NEDDP is a little higher than that of EHDPET.Comonomers of both EHDPET and NEDDP are terephthalic acid(TPA),ethylene glycol(EG)and polyethylene glycol(PEG).Additional,EHDPET has a fourth comonomer,5-sodium sulfo bis(-hydroxyethyl)isophthalate(SIPE).EHDPET and NEDDP all exhibited a pseudoplastic fluid behavior.Apparent viscosity of them decreased with the decrease of melting point.Their melt indexes of EHDPET and NEDDP increased with increasing temperature,and that of EHDPET is higher.No-newtonian index of them is lower than 1 under all testing temperature and the index increased with increasing temperature.Under the same temperature,non-Newtonian index of EHDPET is higher than that of NEDDP.Viscous activation energy of them all decreased with increasing shear rate.Under the same shear rate,viscous activation energy of EHDPET is higher than that of NEDDP.As composite spinning raw materials,the rheological properties of EHDPET and NEDDP are similar.Several kinds of preoriented yard(POY)and draw texturing yard(DTY)of sea-island fibers were prepared.The morphology,mechanical properties,and dyeing properties after splitting were studied through a series of characterization methods.Main results achieved in this paper are listed as following:1.EHDPET/NEDDP sea-island composite fibers were successfully prepared with ratios as 70/30,72/25,80/20 and 85/15.The independent island component in each fiber is separate,and achieves good mechanical properties.The optimized splitting process of four kinds fibers were obtained.The dyeing rate of four kinds of superfine fibers increases with increasing dyeing temperature or increasing island component content.Four kinds of fibers all could be deeply dyed.2.With a EHDPET/NEDDP ratio of 80/20,the effect of spinning temperatures on sea-island composite fiber were investigated,which contribute to industrialization of sea-island composite fiber with low sea component content.EHDPET/NEDDP sea-island composite fibers show good spinnability under all tested spinning temperatures of island component ranged from 270 °C to 290 °C and that of sea component as 275 ?.Island components in all fibers keep separate.Tensile strength of fibers increases but elongation at break of fibers decreases with increasing temperature of NEDDP.Dying rate of superfine fibers has little change with a variaty of spinning temperatures,which is muchhigher than that of ordinary fibers.NEDDP superfine fibers could be deeply dyedeasier than ordinary fibers.