Study On Copolyester Fibers Modified By BaSO₄Nanoparticles And Its Properties

The great development of our country's warp knitting industry began in the1970s due to therapid development of chemical fiber industry and its application is expanding. Warp knitted fabricsfor sports, as one of the fastest growing areas of warp-knitted products, are more and more populardue to its leisure, comfortable, casual, free and easy cleaning features. In order to make the warpknitted fabrics for sports more functional, more comfortable and more beautiful, the raw materialsused by should have the characteristics of light weight, high strength, quick drying and soft to touch.Polyester fibers, in the primary position of synthetic fibers, have high strength, good dimensionalstability, easy to wash and quick drying. As the main source of warp fibers, polyester has poormoisture management property and less comfort ability compared to natural fibers due to its tightlypacked molecular structure, high crystallinity and lack of hydrophilic groups.Polyethylene glycol (PEG), as hydrophilic monomer was introduced to reform the comfort ofcopolyester fibers in this paper. Meanwhile, in order to increase the workability of the fibers anddecrease the phenomenon of broken wire head in the process of high speed warping, inorganicnano-particles BaSO4was added to prepare modified hydrophilic copolyester fibers in situpolymerization. So the efficiency of the high speed warp knitting would be greatly improved byreducing the friction coefficient between the fibers and godets. The main research contents andconclusions are as follows:(1) In the reaction system of ethanol aqueous, well-dispersed hydrophobic BaSO4nanoparticles were prepared by using the method of in situ surface modification with stearic acid(SA) as surface modifying agent. The prepared BaSO4particles were characterized by means ofnanoparticle size analyzer, fourier transform infra-red spectroscopy (FT-IR), surface contact angle(CA), scanning electron microscopy (SEM) and so on. The results showes that the synthesizedBaSO4particles were a kind of ellipsoid with average size of167nm; The surface of BaSO4particleswas successfully coated by SA, which changed the surface characteristic of BaSO4particles fromhydrophilic to hydrophobic. Futhermore, BaSO4particles with surface treatment could stablysuspend in EG for a long time. (2) Modified hydrophilic copolyesters were prepared by added5wt%content of PEG-4000and0~1.0wt%contents of BaSO4particles in situ polymerization and characterized by means of1H-NMR, SEM, differential scanning calorimetry (DSC), thermal gravity analysis (TGA), CA and soon. The results indicates that most parts of the PEG-4000were embedded in the molecular chain ofpolyester, reduced the contact angle from85.62°to82.10°, so the hydrophilic property of PET-PEGcopolyesters was enhanced; Trace addition of BaSO4particles with surface treatment had noinfluence on the polymerization and could well disperse in copolyester. The crystallization propertywas promoted by those well-dispersed particles as heterogeneous nucleating agents and the gloss ofcomposites was little effected by treated BaSO4particles and its L value was about68.(3) Modified copolyester fibers were prepared by spinning process, then the structure andproperties of fibers were studied by using X-ray diffraction (XRD), sonic velocity orientation test,filament strength tester, friction coefficient tester, moisture regain, and Datacolor methods. Theresults showed that the fineness of prepared fibers was61~64dtex/36f and the breaking strength was3.82~4.20cN/dtex, which could meet the subsequent application of weaving. The crystallinity andorientation degree of fibers were reduced by the addition of PEG, which improved the flexibility andmoisture absorption of the copolyester fibers, and its moisture regain was increased to0.52%; BaSO4particles were in favor of improving the crystallinity and orientation degree of fibers. Themechanical strength of the fibers was improved and the friction coefficient of fibers was reducedwith the increase content of BaSO4particles. The depth value of dyeing fabrics (K/S) was alsodeepened by adding PEG and nano-particles BaSO4. Especially, the comprehensive performance ofthe fibers with5wt%content of PEG and0.5wt%content of BaSO4particles showed the best, thetensile strength of the fibers was4.19cN/dtex, the dynamic friction factor was0.73and the K/S was12.28.