• Textile Coloration and Finishing
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• v.34 no.3
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• pp.197-206
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• 2022

The purpose of this study was to confirm the optimal spinning conditions for PLA (Polylactic acid) as a fiber forming polymer. According to the melt spinning test results of PLA, the optimal spinning temperature was 258℃. However, it needs to note that relatively high pack pressure was required for spinning at 258℃. At an elevated temperature, 262℃, mono filament was broken easily due to hydrolysis of PLA at a higher temperature. In case of fiber strength, it was confirmed that the draw ratios of 2.7 to 3.3 were optimal for maximum strength of melt spun PLA. Above the draw ratio, 3.3, the strength of the PLA fibers was lowered. It was presumed that cleavage of the PLA polymer chain over maximum elongation. The heat setting temperature of GR (Godet roller) showed that the maximum strength of the PLA fibers was revealed around 100℃. The degree of crystallinity and the strength of the PLA fibers were decreased above 100℃. The optimal take-up speed (Spinning speed) was around 4,000m/min. Thermal analysis of PLA showed 170℃ and 57℃ as Tm (melting temperature) and Tg (glass transition temperature), respectively.

• Clean Technology
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• v.15 no.4
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• pp.245-252
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• 2009

Profiles development of melt spinning process of poly(lactic acid) (PLA) was simulated via a numerical method and the radial temperature distribution was calculated using finite difference method. The spinning speed ranged from 1 km/min to 5 km/min was analyzed and the effect of spinning conditions on the radial temperature distribution was investigated. At low spinning speed, the difference between PLA and poly(ethylene terephthalate) (PET) was relatively small. As the spinning speed increased, the difference in velocity profile became prominent. PLA showed a slower spinning speed than PET and solidified more slowly. The temperature difference between the core and surface of the PLA filament reached 4.6 K, which was less than that of PET filament with a difference of 10.4 K. The radial temperature difference increased with increasing the cooling-air velocity and the spinning temperature.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.3
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• pp.124-128
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• 2011

Electrospun webs have been widely investigated for applying to drug delivery system (DDS) because of their high specific surface area and high porosity. In this study, the composite webs of PLA (poly(lactic acid)) and $TiO_2$ were fabricated by melt-electro-spinning method for applying to drug delivery system. The morphologies of PLA/$TiO_2$, webs were observed using scanning electron microscope (SEM) and field emission transmission electron microscope (FE-TEM). The crystal structures of PLA/$TiO_2$ composite webs were confirmed by X-ray diffractometer (XRD).

• Polymer(Korea)
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• v.33 no.6
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• pp.581-587
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• 2009

PLA/PEG blend fibers composed of poly (lactic acid) (PLA) and poly (ethylene glycol) (PEG) were prepared via melt blending and spinning for bioabsorbable filament sutures. The blend fibers hydrolyzed with the immersion in a phosphate buffer solution at pH 7.4 and $37\;^{\circ}C$ for 1~8 weeks. The effects of blending time, blend composition, and hydrolysis time on the weight loss and tensile strength of the hydrolyzed blend fibers were investigated. After hydrolysis, the weight loss of the blend fibers increased with increasing PEG content, blending time, and hydrolysis time. The tensile strength and tensile modulus of the blend fibers decreased with increasing PEG content, blending time, and hydrolysis time. Therefore, it can be concluded that the weight loss of the PLA/PEG blend fibers was less than 0.9% even at hydrolysis time of 2 weeks and their strength retentions were over 90%.

• Fibers and Polymers
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• v.6 no.1
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• pp.13-18
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• 2005

PLA/LPCL/HPCL blend fibers composed of poly (lactic acid) (PLA), low molecular weight poly ($\varepsilon$-caprolactone) (LPCL), and high molecular weight poly ($\varepsilon$-caprolactone) (HPCL) were prepared by melt blending and spinning for bioab­sorbable filament sutures. The effects of blending time and blend composition on the X-ray diffraction patterns and tensile properties of PLA/LPCL/HPCL blend fibers were characterized by WAXD and UTM. In addition, the effect of in vitro degra­dation on the weight loss and tensile properties of the blend fibers hydrolyzed during immersion in a phosphate buffer solu­tion at pH 7.4 and 37$^{\circ}C$ for 1-8 weeks was investigated. The peak intensities of PLA/LPCL/HPCL blend fibers in X-ray diffraction patterns decreased with an increase of blending time and LPCL contents in the blend fibers. The weight loss of PLA/LPCL/HPCL blend fibers increased with an increase of blending time, LPCL contents, and hydrolysis time while the tensile strength and modulus of the blend fibers decreased. The tensile strength and modulus of the blend fibers were also found to be increased with an increase of HPCL contents in the blend fibers. The optimum conditions to prepare PLA/LPCL/HPCL blend fibers for bioabsorbable sutures are LPCL contents of $5 wt\%, HPCL contents of $35 wt\%, and blending time of 30 min. The strength retention of the PLA/LPCL/HPCL blend fiber prepared under optimum conditions was about $93.5\% even at hydrolysis time of 2 weeks.

• Journal of the Korean Society of Clothing and Textiles
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• v.30 no.4 s.152
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• pp.607-614
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• 2006

This study was carried out to suggest the optimal spinning process condition which provides a proper range of tenacity and biodegradability as textile fibers. The effects of the melt spinning speed and heat treatment on the mechanical property and biodegradability of polylactic acid fiber were investigated. Polylactic acid(PLA) was spun in a high spinning speed of $2000{\sim}4000m/min$. Each specimen was heat-treated at $100^{\circ}C$ during 30min. Mechanical properties such as breaking stress and the degree of crystallinity were evaluated using WAXS. Biodegradability was estimated from the decrease of breaking stress, weight loss, and the degree of crystallinity after soil burial. Experimental results revealed that heat treated specimens showed higher breaking stress than untreated specimens, but the increase was not so high as was expected from the remarkable change of crystallinity by heat treatment. It was concluded that breaking stress was more influenced by spinning speed than heat treatment. In the soil burial test, however biodegradability calculated from weight loss was more influenced by heat treatment than spinning speed.