| Polyethylene terephthalate(PET) fibers have many excellent properties such as high breaking strength and elastic modulus, moderate rebound resilience, excellent heat resistance, good wash durability, good corrosion resistance, excellent stability to weak acid and weak base because its macromolecules are linear, closely arranged and symmetrical structure. Also, the degree of crystallinity and orientation of melt-spun PET fibers are high, and its glass transition temperature is about78℃. As the largest use of synthetic fiber, there are two main problems for PET fiber:on the one hand, PET macromolecule lacks hydrophilic groups and its moisture regain is only0.4%under standard atmospheric conditions, resulting in poor water absorption and dyeing, high static electricity and unsatisfactory skin comfort properties for ordinary PET fiber, which limit its application in a certain extent; on the other hand, due to the homogenization of competition, the PET fiber capacity is serious excess and industry benefits declines, so it is necessary to look for new market breakthrough. Therefore, the hydrophilic and functional modifications for PET fibers to improve its moisture absorption and to enrich in fiber varieties, and increase their added value, have important theoretical significance and practical value.The ideal surface modification of PET fibers should possess good durability, good economic benefit and environment-friendly without compromising the original excellent performance. As a commonly used ionizing radiation, electron beam (EB) irradiation process is widely used in the modification of polymeric materials, which has environment-friendly, continuous operation, batch processing, low cost and little damage to the materials. Therefore, EB irradiation as a means for the modification of PET fibers in this paper, the structure and properties of PET fiber and fabric were studied after EB irradiation, and then the grafting modification of antibacterial, hydrophilic and moisturizing skin-close sre investigated, preparing the PET fiber with different functions. The main works are as follow:(1) Structure and properties of PET fibers and fabrics after EB direct irradiation were studied. The structure and properties of irradiated PET fibers and fabrics were characterized by ESR, XRD, FT-IR/ATR, strength and elongation tester, SEM, DSC, TG and so on. The effects of irradiation dose and irradiation atmosphere were also investigated. The results showed that:①The free radicals produced on PET macromolecules by EB irradiation were-CH2-CH-, which was the necessary prerequisite for the subsequent grafting and function modification.②The degradation of PET macromolecules occurred during irradiation at air atmosphere, and the viscosity average molecular weight of PET fibers decrease with the increase of irradiation doses; When the irradiation dose was300kGy, the molecular weight of PET fibers at different irradiation atmosphere were Mη-oxygen>Mη-air>Mη-nitrogen.③The crystal structure of PET fibers was not changed, but the crystallinity increased after EB irradiation.④DSC analysis showed that the melting point of PET fibers increased after irradiation, but decreased with the increase of irradiation dose. When the dose increased to500kGy, the melting peak widened and showed two peaks in DSC curve. TG analysis showed that the decomposition temperature of the fiber increased with the increase of irradiation dose. The decomposition temperature of non-irradiated PET fibers was437.9"C. which increased to441.2℃at the dose of400kGy and439.11℃at500kGy.⑤The surface roughness of PET fiber increased with the increase of irradiation dose. When the irradiation dose was400kGy, there were a lot of "island-like" bulges on the fiber surface, and the etched surface of PET fiber became more serious under500kGy, which showed plenty of gullies and cracks on the "island-like bulges.⑥On the one hand, the breaking strength of PET fibers after EB irradiation decreased, which dropped3.8%when the dose was50kGy, then increased with the increase of irradiation dose. The breaking strength increased to the level of non-irradiated fiber when the dose was200kGy. then began to decline when the irradiation dose exceeded200kGy. On the other hand, the breaking elongation decreased after EB irradiation. When the irradiation dose was lower than200kGy, the breaking elongation was lower than the non-irradiated PET fiber, but the breaking elongation increased with the increase of irradiation dose and higher than the non-irradiated PET fiber after higher than200kGy.⑦When the dose was lower than350kGy, the drip diffusion time of PET fabric after EB irradiation was lower than non-irradiated PET fabric, indicating the hydrophilic properties of PET fabric increased after irradiation, while the drip diffusion time increased above350kGy, so its hydrophilic properties decreased. Similar to the plasma treatment, there was also "immediate effect" for PET fabric under EB irradiation, which indicated that the hydrophilic properties of the fabric would decrease with the extension of storage time.(2) The grafting modification of antibacterial of PET fiber by EB irradiation was studied. Using EB irradiation, dimethylaminoethyl acrylate (DMAEA) was grafted on PET fiber surface and then quatcrnized treatment, preparing the antibacterial properties of modified PET fibers. The influences of irradiation dose, monomer concentration, liquor ratio and solvent on the grafting yield were investigated, and the mechanism and kinetics of the graft copolymcr using EB irradiation was discussed.①Using co-irradiation grafting copolymcrization and toluene as solvent. DMAEA was successfully grafted on PET fiber surface. It found that the grafting yields increased with the increase of EB irradiation dose and monomer concentration, while increased first and then decreased with the increase of liquor ratio. Under the experimental conditions, the optimum reaction conditions were radiation dose of100kGy. monomer concentration of50%and liquor ratio of1:20.②The PET surface grafted PDMAEA was treated using methyl iodide and benzyl chloride, the results showed that the quaternized effect with the former is better than the latter, building antibacterial surface based polycationic modification by the quaternized treatment. The antibacterial test showed that the sterilization rate of grafted samples with methyl iodide quaternized was75%after60minutes, while the sterilization rate was60%with benzyl chloride. The antibacterial performance enhanced with prolonged contact time of modified fibers and bacteria.(3) Using EB irradiation, the grafting modification of hydrophilic of PET fiber was studied. Selected2-acrylamido-2-methylpropane sulfonic acid (AMPS) and acrylic acid (AA) as grafting copolymer monomers were grafted on PET fiber by FB irradiation to improve its hydrophilic properties. The grafting condition of two-component monomers and the influences of irradiation dose, monomer concentration, liquor ratio, the amount of inhibitor and AA/AMPS molar ratio on the grafting yield were investigated.①The grafting yields of AA/AMPS on PET fibers increased with the increase of irradiation dose and monomer concentration, and its grafting yields grew slowly when the dose was above30kGy. There were maximum values for the liquor ratio and the amount of inhibitor on grafting yield. With the AA/AMPS ratio decreased, the grafting yields increased first and then decreased, which also had an optimum value. Under the experimental conditions, the optimal reaction conditions were irradiation dose of30kGy, monomer concentration of50%. liquor ratio of1:35. FcSO4·7H2O of1.75×102mol/L and AA/AMPS molar ratio of9:1.②It is very difficult for AMPS grafted on PET fibers, so the grafting yield was very low The grafting yields of AA/AMPS were higher than AA and AMPS grafted separately, which indicated that AA and AMPS had synergistic effect in grafting copoly merization.③AA/AMPS had been successfully grafted on the PET fiber surface, and the crystalline configuration of grafted fibers had not changed, but the crystallinity increased. The melting point of grafted PET fibers increased slightly, while TG analysis showed that the temperatures of the weight loss of5%,10%,45and maximum weight loss rates decreased and the temperatures of same the weight loss rate were lower when the grafting yields were higher.④With the increase of AA/AMPS grafting yields, the moisture regain of PET fibers increased. When the grafting yield was20%. its moisture regain was up to2.63%. While the grafting yield was12.4%, its wicking height increased from4.6cm ungrafted fabric to11.2cm. which had not almost changed after washing.(4) The moisturizing and skin-friendly modification of PET fiber by EB irradiation was studied. Vinyl acetate (VAc) and glycidyl methacrviate (GMA) were grafted on PET fiber surface by EB irradiation firstly, and then collagen and hy aluronic acid were immobilized on the surface with chemical bond respectively, which provided a new method for preparing PET fiber materials with moisturizing and skin-friendly features.1) The influences of various factors on VAc grafting yields were studied, such as irradiation dose, monomer concentration, liquor ratio and polymerization inhibitor, and hydrolysis with HCl concentration and processing time was investigated, and the immobilized effects for fiber surface under different collagen concentration were investigated. The results showed that:①The grafting yields increased with the increase of irradiation doses, while monomer concentration, liquor ratio and the amount of CuSO4on grafting yield had an optimum value respectively. Under the experimental conditions, the optimal reaction conditions were radiation dose of100kGy, monomer concentration of60%. liquor ratio of1:30and the amount of CuSO4of0.5%(w/w).②The degree of hydrolysis of polyvinyl acetate grafted PET fiber samples increased with HCl concentration and treatment time, and the wicking height of obtained sample decreased from8.6cm to4.63cm of pure PET fabric.③Collagen was then immobilized on fiber surface using glutaraldchyde as a bridge agent, the hydrophilic properties of modified PET were further improved and its wicking height increased to13.2cm. which had still good hygroscopicity with wicking height of11.8cm after washed5times.④By the FT-IR/ATR. XPS and SEM analysis, it confirmed that collagen has been successfully immobilized on the PET fiber surface with covalent bond.⑤When PET fabrics immobilized collagen contacted with skin for three days, it found that the skin felt moister and smoother relatively than pure PET fabric, and there was no irritation or itching feeling for skin.2) The influences of various factors on GMA grafting yields were studied, such as irradiation dose, monomer concentration and liquor ratio. And then PET fiber surface were linked hyaluronic acid with covalent bond by ring-opening reaction, and the influences of different concentration and treatment time on the surface of immobilizing hy aluronic acid were investigated. The results showed that:①The GMA grafting yields increased with the increase of irradiation dose and monomer concentration, while there was a maximum value when the liquor ratio was1:25, which was similar with the laws of vinyl acetate graft.②When the hyaluronic acid concentration was0.3g/100ml, the water absorption and wicking height of the modified PET fabrics were124.3%and14cm, respectively, and the immobilized hyaluronic acid and its water absorption increased with the processing time. After washed5times, the surface density of immobilized hyaluronic acid on PET fabric surface reduced from0.94g/m2to0.62g/m2, while its wicking height decreased from14cm to10.1cm, which still had good hygroscopic property.③With the time for PET fibric immobilized hyaluronic acid contacted on skin, the surface of skin felt more moist and smooth, but the overall feel was worse slightly than the PET fabric immobilized with collagen.In this paper, the structure and properties of PET fiber and fabric after EB irradiation were studied. The generation of free radicals on the surface of PET fiber after EB irradiation was the foundation for surface modification and functionalization. Using EB irradiation, the PET fiber and fabric with antibacterial, hydrophilic and skin-care effect were prepared, which provided a new technology and preparation method for the hydrophilic and skin-care modification of PET fibers. These would be important significance in the functionality of PET fiber. |
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