| In recent years, the rapid development of polymer materials has provided great convenience to human life. Meanwhile, it leaves some problems to environmental pollution. Biodegradable materials is one of the effective ways to solve these problems. Aliphatic- aromatic copolyester is one of the biodegradable materials which combines excellent degradability of aliphatic polyester and good mechanical, thermal properties of aromatic polyester. Poly(butylene adipate-butylene terephthalate)(PBAT) is such a typical aliphatic-aromatic copolyester. However, due to its chemical structure, the mechanical properties couldn't meet the requirements of some special fields. Therefore, we tried to improve the performance of PBAT materials by the method of ultraviolet crosslinking.Based on the characterization of PBAT, the relationship among the spinning process, fiber structure and performance was studied. The structure and properties of PBAT fiber were modified by ultraviolet crosslinking, as well as the properties of dyeing and degradation of ultraviolet crosslinked fiber.It was shown that the decomposition temperature of PBAT is around 382 ?, both in the atmosphere of nitrogen and air. Its melting temperature(Tm) is 119 ?, and the melting peak is relatively wide. The melt index(MI) of PBAT increased gradually with the temperature increasing. When the temperature is 200 ?, the MI is 7.4 g/10 min. Therefore, the range of spinning temperature is determinded from 190? to 220? based on the above data.The PBAT fibers were prepared by melt-spinning, and drawing. The effects of drawing medium, temperature and drawing ratio on structure and properties of fibers were studied. With the spinneret draft ratio increasing, the strength and modulus of as-spun fiber increased gradually, while elongation at break decreased. The PBAT fibers were drawn in the medium of water and air, while the crystal orientation of fiber in the air-draft is higher than it in the water-bath. With the increase of drawing temperature, the fibers' orientation becomes higher. At 75 ?, in the airdraft, the fibers' orientation grows to the maximum value of 0.74. The variation trend of crystallinity is the same as the orientation.Compared with the water-bath condition, the mechanical properties of PBAT fiber by air-draft are better. With the draft ratio increasing, the fibers' strength improved at first. When the drawing temperature is 75? and draft ratio is 5.4, the strength and modulus reached the maximum value, respectively 2.7 cN/dtex and 4.8cN/dtex.PBAT fibers were modified by ultraviolet crosslinking, and the effects of the photoinitiators BP as well as the photo-crosslinker TAIC on structure and properties of PBAT were studied. It was shown that the gel content and the mechanical property are better, when the mass percentage of BP is 0.5%, and TAIC is 1.5%, respectively. Compared with the pure PBAT fiber, the crystallinity(Xc) of crosslinked fibers decreased slightly, while the fiber orientation remained. With the irradiation time changed, it has a little influence on the sonic orientation and thermal properties of crosslinked fibers. When the irradiation time is 45 s, the gel content reaches the maximum value and the mechanical properties is better. It indicates the mechanical properties of fibers can be greatly improved by ultraviolet crosslinking.PBAT fibers of uncrosslinked and crosslinked were dyed with disperse blue and disperse red. The dyeing properties of PBAT fibers was analyzed by the dye-uptake rate, Integ value and level-dyeing property. While the temperature of dye bath increased, the dye-uptake rate is gradually growing to a stable region at 70?. The dye-uptake rate of the crosslinked fiber was slightly lower than that of the uncrosslinked. The higher temperature of dye bath is, the greater the Integ values of the PBAT fibers grow. In addition, for the Integ values, the disperse blue is higher than that of the disperse red. While the time of dye bath increased, the dye-uptake rate of disperse red beacomes balanced in 70 min, and balance time of disperse bule is 90 min. Moreover, as to the the disperse red, the level-dyeing property is better than of the disperse bule, but its penetration ability is poor.Additionally, the degradation property of PBAT fibers before and after crosslinking were carried out in the presence of buffers, a lipase originated from Pseudomonas cepacia and soil environment. As time goes on, the remaining weight loss and strength show a downward trend in the buffers and lipase. Under the soil environment, the degradation rate of uncrosslinked fibers is the most rapid decline, and the mechanical properties is obviously decreased. The surface of uncrosslinked fibers is damaged definitely. After degradation, the crosslinked PBAT fibers still keep a great strength. |
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