• Fibers and Polymers
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• 제7권4호
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• pp.380-388
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• 2006

Fully biodegradable and environment-friendly green composite specimens were made using ramie fibers and soy protein concentrate (SPC) resin. SPC was used as continuous phase resin in green composites. The SPC resin was plasticized with glycerin. Precuring and curing processes for the resin were optimized to obtain required mechanical properties. Unidirectional green composites were prepared by combining 65% (on weight basis) ramie fibers and SPC resin. The tensile strength and Young's modulus of these composites were significantly higher compared to those of pure SPC resin. Tensile and flexural properties of the composite in the longitudinal direction were moderate and found to be significantly higher than those of three common wood varieties. In the transverse direction, however, their properties were comparable with those of wood specimens. Scanning electron microscope (SEM) micrographs of the tensile fracture surfaces of the green composite indicated good interfacial bonding between ramie fibers and SPC resin. Theoretical values for tensile strength and Young's modulus, calculated using simple rule of mixture were higher than the experimentally obtained values. The main reasons for this discrepancy are loss of fiber alignment, voids and fiber compression due to resin shrinking during curing.

• 폴리머
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• 제38권4호
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• pp.477-483
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• 2014

Poly(lactic acid) (PLA) and poly(${\varepsilon}$-caprolactone) (PCL) blends with various components for melt-blown non-wovens were prepared by a twin-screw extruder. Tributyl citrate (TBC) was added in order to improve the miscibility between PLA and PCL. The results showed that small circular particles of PCL were dispersed in PLA matrix uniformly. The addition of PCL had the heterogeneous nucleation effect on the crystallization of PLA and decreased thermal stability of PLA. The flow of pure PLA and blends approached to Newtonian liquid at a low shear rate and expressed more obvious viscoelasticity at a high shear rate.

• 한국염색가공학회지
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• 제31권3호
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• pp.147-154
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• 2019

In this study, poly(ethylene terephthalate)(PET) fibres dyed with Disperse Red 167 using supercritical $CO_2$ technology. The purpose of this study was to investigate relationship between PET fibers and supercritical $CO_2$ during dyeing. The effects of temperature, pressure, dyeing time and mass ratio between the dye and PET in the dyeing chamber were considered. Thermal and mechanical properties of the fibers were investigated. Tensile strength of dyed PET fibers decreased at higher temperature and pressure conditions. DSC and DMA results indicated that the Tg and Tm values decreased significantly when compared to the pure PET fibers. However, uniformly dyed PET fibers were typically observed.

• Journal of Plant Biotechnology
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• 제49권3호
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• pp.257-270
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• 2022

The aim of this work was to prepare a new biodegradable polyhydroxybutyrate (PHB) submicron fiber mat loaded with hypericin-rich Hypericum perforatum raw extract by centrifugal spinning technology, an alternative approach to the traditional method of electrospinning to fabricate nanofibers or microfibers from solutions at high speed and low cost. Hypericins in methanol/acetone extract of H. perforatum were determined by UHPLC-MS/MS and HPLC/PDA. Submicron fiber mats composed of pure PHB or PHB enriched with H. perforatum extract were prepared using a pilot plant demonstrator for the centrifugal spinning technology and characterized by SEM. Singlet oxygen production was quantified by the 1,3-diphenylisobenzofuran (DPIBF) method in hexane. The results proved a significant production of singlet oxygen by the prepared submicron fiber mat. We also found a significant antibacterial activity against the bacterial strain Escherichia coli CCM 5417 by a method in accordance with JIS Z 2801/ISO 22196 standards. The H. perforatum extract-enriched PHB submicron fiber mats showed potential for the development of self-cleaning and antimicrobial air filters.

• Computers and Concrete
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• 제32권2호
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• pp.173-184
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• 2023

In this study, mechanical, flexural post-cracking, and torsional behaviors of recycled steel fiber-reinforced concrete (RSFRC) incorporating steel fibers obtained from recycling of waste tires were investigated. Initially, three concrete mixes with different fiber contents (0, 40, and 80 kg/m³) were designed and tested in fresh and hardened states. Subsequently, the flexural post-cracking behaviors of RSFRCs were assessed by conducting three-point bending tests on notched beams. It was observed that recycled steel fibers improve the post-cracking flexural behavior in terms of energy absorption, ductility, and residual flexural strength. What's more, torsional behaviors of four RSFRC concrete beams with varying reinforcement configurations were investigated. The results indicated that RSFRCs exhibited an improved post-elastic torsional behaviors, both in terms of the torsional capacity and ductility of the beams. Additionally, numerical analyses were performed to capture the behaviors of RSFRCs in flexure and torsion. At first, inverse analyses were carried out on the results of the three-point bending tests to determine the tensile functions of RSFRC specimens. Additionally, the applicability of the obtained RSFRC tensile functions was verified by comparing the results of the conducted experiments to their numerical counterparts. Finally, it is noteworthy that, despite the scatter (i.e., non-uniqueness) in the aspect ratio of recycled steel fiber (as opposed to industrial steel fiber), their inclusion contributed to the improvement of post-cracking flexural and torsional capacities.

• Asian-Australasian Journal of Animal Sciences
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• 제21권2호
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• pp.245-251
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• 2008

The effects of feeding diets containing 20% (L) or 30% (H) neutral detergent fiber (NDF) (DM basis) on performance and carcass traits were studied in three breeds of pig, including pure Mong Cai (MC), crossbred Landrace$\times$Yorkshire (LY) and crossbred MC$\times$Yorkshire (F1). The experiment had a factorial design with two factors, breed and diet. Eighteen piglets of each breed ($60{\pm}3days$) were randomly allocated to three treatments: L-L, low fiber diet in both growing and finishing periods; L-H, low and high fiber diet in the growing and finishing period, respectively; and H-H, high fiber diet in both periods. The diets were iso-energetic and iso-nitrogenous within feeding period. The main fibrous ingredients of the diets were rice bran and cassava residue. There were no effects of fiber level on daily dry matter feed intake (DMI), expressed as g/kg metabolic body weight (BW0.75), in both feeding periods (p>0.05). DMI was highest for MC, followed by F1 and LY (p<0.001). Average daily gain (ADG) in L-L and L-H was higher than in H-H in the growing period (p<0.001) and overall (p<0.05), while feed conversion ratio (FCR) was higher in H-H than in L-L and L-H in the growing period (p<0.05) and overall, but no significant differences between treatments were found in the finishing period. In both periods, Landrace$\times$Yorkshire had the highest ADG and the lowest FCR, followed by F1 and Mong Cai (p<0.001). There were no interactions between breed and diet for performance and carcass traits. Carcass and dressing percentage was lower for L-H and H-H than for L-L (p<0.05). There were no significant differences among treatments in back fat thickness and lean meat percentage, or in crude protein and ether extract contents of lean meat. Carcass, dressing and lean meat percentage was highest for LY, lowest for MC and intermediate for F1 (p<0.001). It can be concluded that feeding a high fiber diet in the growing period reduced pig performance, but there was no effect in the finishing period. Pure Mong Cai pigs are not particularly suitable for meat purposes, although the F1 cross with Large White had reasonably good growth performance and carcass quality.

• Journal of the Korean Wood Science and Technology
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• 제48권6호
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• pp.878-887
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• 2020

A neutral extract (NE), that is soluble in cold water and has excellent antioxidant activity, from Pinus radiata pine bark was prepared by sodium bicarbonate treatment, and its chemical characteristics were investigated. NE was prepared by treating P. radiata bark with 0.8% NaHCO₃ aqueous solution with a 5 : 1 liquor-to-bark ratio at boiling temperature for 1 h, resulting in 44% yield and final pH of 6.66. The yield of NE was 11% higher than that of the hot water extract (HWE) due to the increase in the solubility of polyphenols, the main component in the bark, by NaHCO₃ treatment. NE was characterized through FT-IR, NMR, and MALDI TOF MS analyses. The results indicated that NE is mostly composed of proanthocyanidins (PAs) consisting of procyanidin (PC) units. The acetylated neutral extract (Ac-NE) had weight average molecular weight (${\bar{M}}w$) of 5,300 Da. The Ac-NE had wide molecular weight distribution and its polydispersity (${\bar{M}}w/{\bar{M}}n$) was 6 times higher than that of pure PA. The antioxidant activity of NE was determined by 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay and showed that NE had comparable antioxidant activity with pure PA.

• 한국염색가공학회지
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• 제19권6호
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• pp.28-34
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• 2007

The optical and physical properties of alkyl-substituted anthraquinoid dyes were investigated in terms of dyeing of pure polypropylene fiber. The length of alkyl substituents of the dyes did not affect the molar extinction coefficient and maximum absorption wavelength of them. The use of a double-tailed cationic surfactant, didodecyldimethylammonium bromide(DDDMAB), could make the hydrophobic dyes dispersed in water effectively. As the amount of DDDMAB increased, the average particle size of dye dispersion decreased. Maximum color strength of the fabrics was shown in the case that 1.5 molar ratio of DDDMAB was used. As for the fastness properties, commercially acceptable result was obtained in general.

• 대한수의학회지
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• 제48권4호
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• pp.501-503
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• 2008

An adult one-year-old male Eurasian beaver (Castor fiber) died of a traumatic injury to its right leg from a fall. At necropsy, fibrinopurulent exudates were observed in the thoracic cavity. Histopathologic examination showed that the pericardium, thoracic wall, pulmonary pleura and the lungs were markedly thickened due to mixtures of necrotic cellular debris, neutrophils, fibrin, red blood cells, and bacterial aggregates. Pure culture of Klebsiella (K.) pneumoniae was isolated from the thoracic exudates, pleura and heart tissues. Based on these findings, this is the first report describing pleuritis and pericarditis associated to K. pneumoniae in a beaver.

• 한국염색가공학회지
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• 제18권5호
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• pp.30-34
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• 2006

Polypropylene fiber was dyed with 4 super hydrophobic dyes having different alkyl derivatives on the same chromophore. Double-tailed cationic surfactant, didodecyldimethylammonium bromide(DDAB), was used to make dye-dispersant complex to improve the dispersion of dyes. As the alkyl groups are longer and the hydrophobicity is increased, the dyeability onto polypropylene fiber was improved and deep coloration was obtained. As for the fastness properties, wash fastness was relatively good, while light fastness was bit low.