• Korean Journal of Human Ecology
• /
• v.6 no.1
• /
• pp.27-34
• /
• 2003

We investigated the bacterial and chemical retting conditions of ramie grown in Hansan. Bacterial retting was done in troughs at a temperature of 30${\pm}$2$^{\circ}C$ for 1, 2, 3, 4, 5, 6 and 10 days. Chemical retting(CR) was done at the different conditions using sodium silicate (Na$_2$SiO$_3$), sodium carbonate(Na$_2$CO$_3$) and sodium hydroxide(NaOH) as alkali solutions. The retting solution was boiled during 1. 2, 4 and 6 hours respectively at the different concentration(0.5, 2.0, 4.0, 6.0. 8.0 %) with decorticated ramie stems submerged in it. The treated ramie was then rinsing with running tap water thoroughly, which was further soaker in 0.5% acetic acid (v/v) solution for three minutes and washed thoroughly with distilled water. Finally ramie was dried for 2 hours in vacuum oven at 100 $^{\circ}C$. To know change of ramie fiber characteristics retted at the different conditions, weight loss, fiber bundle strength were tested and color, texture, luster etc. were also sensually evaluated. The results were as follows. $.$ Weight loss of ramie retted in each alkali solutions were about 10%, 20% and 30% in sodium silicate, sodium carbonate and sodium hydroxide, respectively. $.$ Chemical retting was faster than bacterial retting, but the color of chemically retted ramies were worse than that of bacterially retted ramies. $.$ The combination of bacterial and chemical processing showed some merits. A combination of either 2 or 3 days of bacterial and then chemical retting might provide the best quality ramie. $.$ Ramie fiber became cottonized ramie when retted in 8% NaOH solution for 6-8hours.

• Korean Journal of Microbiology
• /
• v.26 no.1
• /
• pp.60-66
• /
• 1988

Dynamics of bacterial communities and its colonization under aerobic gemp retting were observed in air lift fermentor as a closed system, unlike conventional hemp retting as an open system. Dried hemp which was harvested in both 1986 and 1987 was retted at room temperature. Predominant community was facultatively anaerobic Gram-negative rods, and its density was increased from $3.0\times 10^{7}$ cells/ml to $9.0\times 10^{8}$ cells/ml. The density of facultatively nanerobic Gram-positive fods was maintained at the lovel of $5.0\times 10^{6}$ cells/m, and this Gram-positive bacterial community was not participated in retting. In the Gram-negative bacterial community during the retting, five types of colonieswere developed at early stage of pH7.0-8.0, and thereafter, only three types were colonized till later stage, shich were identified as pectolytic strain Erwinia salicis, Erwinia tracheiphila and Enterobacter agglomerans. A community of facultatively Gram-negative rods was mainly proliferated in stems and dispersed into liquor after 6-8 hours. Retting was terminated within 70-80 hours.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.31 no.11
• /
• pp.1565-1573
• /
• 2007

This research was aimed to investigate the effect of $K_2CO_3$ instead of NaOH on retting of the kenaf bast. We examined the relationship between separation of fiber bundle and tensile strength besides observing the color, handle and cross sectional view for the kenaf fiber retted with various concentration(100, 150, 200, 250, 500, 1000mmol) of $K_2CO_3$ and double retted with 0.5% pectinase after $K_2CO_3$ retting. The one retted on low $K_2CO_3$ concentration, $150{\sim}200mmol$, showed the best result on color, handle and luster. The separation of fiber bundle started even at the low $K_2CO_3$ concentration, 100mmol, and as the $K_2CO_3$ concentration was higher, the size of the fiber bundle was smaller. In the case of 1000mmol, the fiber bundle became irregular, but they were breaking up into certain way. Regardless of $K_2CO_3$ concentration, the thinner the diameters of the kenaf fiber bundle, the stronger tensile strength have appeared. This result corresponds with the result of cross sectional view. Retting on $150{\sim}200mmol\;K_2CO_3$ concentration was most effective on fiber bundle#s separation and tensile strength. The one with double retted with 0.5% pectinase after $K_2CO_3$ retting showed very small size of fiber bundle and low tensile strength compare to the one just retted on $K_2CO_3$. This decrease of tensile strength seem to be related to damage of the fiber resulted by excessive fibrillation.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.28 no.7
• /
• pp.873-881
• /
• 2004

This research was aimed to investigate the effect of enzyme and the addition of chelators on rotting of the Kenaf bast. Enzyme rotting was effective only when the chelators were added with the enzyme. EDTA was a more effective chelator than oxalic acid under 1% concentration. There was no difference in the rotting effect under different enzyme concentration levels, and under different treatment time and temperature. Therefore, it was found that enzyme rotting can be carried out with low enzyme concentration(0.125%) at room temperature. Retting time can be shortened when higher enzyme concentration and higher temperature are applied. Cellulose I structure of kenaf fiber did not change after enzyme rotting, and different enzyme concentration did not affect the crytallinity structure. Non-cellulosic matters such as hemicellulose, lignin, and pectin were present in the descending order in the enzyme rotted kenaf fiber, and there were no differences in their amounts due to enzyme concentration levels. There was no difference in the dyeabilities of kenaf fiber rotted with different enzyme concentration levels. Enzyme rotted kenaf fiber showed better cyeability when pectin, lignin, and hemicellulose were removed.

• Journal of the Korean Professional Engineers Association
• /
• v.10 no.3
• /
• pp.17-26
• /
• 1977

In order to obtain the most practical and economically efficient method for refining of kenaf fiber and the production possibility of bag dproucts by using kenaf, Various chemicals and conditions of treatment for refining of kenaf bark were examined. Refining by the retting method was found much beneficial in quality of fiber and in processing cost than the chemical mettled. Bag products by using kenaf bark has good quality , and for practical use, Even if the production cost is slightly more expensive than jute bag, it could be reduced by planned mass production.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.32 no.4
• /
• pp.598-607
• /
• 2008

Bast fibers were applied for various usages from fabrics to household care products long time ago. In this study, we investigated the physical characteristrus of water retted & chemically rotted fibers of Yucca, New Zealand hemp, Corn, Kuzu vine, Indian mallow, and Mulberry paper that have been harvested by domestic cultivation. Water retting is more effective than chemical rotting for six kinds of plant fibers. When all fibers were rotted chemically with 1% sodium hydroxide, only Kuzu vine and Indian mallow were retted. Indian mallow, Yucca, New Zealand hemp, and Com fibers have higher tensile strength than any other fibers. The crystallinity of Kuzu vine, Indian mallow, Yucca, New Zealand hemp, and Corn was as low as 60% but Yucca, New Zealand hemp were flexible. Yucca had fewer lumina whereas New Zealand hemp more lumina in cross sectional shape. Especially com fibers have a structure like sponge, and Indian mallow had a net shape. The longitudinal section of New Zealand hemp showed smooth and long shape. Mulberry paper was proved to be short and thin, which is quite appropriate for making paper. In this study, we found that plant fibers for living material could be used for cloth materials.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.27 no.7
• /
• pp.862-871
• /
• 2003

Kenaf has been estimated as an economic and environmentally compatible crop. This study purposed to enlarge the use of kenaf as textile materials and to develope high value-added textile fibers. Kenaf has been cultivated successfully and grown fast in Jeju. The height of kenaf stalks was about 220cm at 105 DAP and 400cm at 150 DAP, After harvesting at 105 DAP and seperating the basts from harvested kenaf stalks, decorticated kenaf basts were rotted in water at 15~$25^{\circ}C$ for biological rotting and were treated with 1%, 4% and 7% NaOH at 9$0^{\circ}C$ for chemical retting. The properties of extracted fibers were compared: such as fiber diameter. Transversal and longitudinal views, colors, crystallinities, strengths and elongations etc. The diameter of kenaf bast fibers was 15~25 ${\mu}{\textrm}{m}$. Biologically rotted kenaf bast fibers had well developed lumens which were diminished after chemical retting. The degree of crystallinities of biologically rotted kenaf bast fiber was about 92~96% showed higher than those of chemically rotting. The biologically rotted fibers were bright and had creamy color. Yelloweness increased at chemically rotted fibers. Fiber bundle strengths were from maximum 98076.9 (gf/g) to minimum 63749.5 (gf/g). Fiber bundle strengths of biologically rotted kenaf fibers appeared greater than those of chemically rotted fibers. Alkali treatments of chemical rotting could make strength lower and elongation higher. Rotting method might be one of the most importance factors affecting to final fiber properties.

• Korean Journal of Medicinal Crop Science
• /
• v.7 no.1
• /
• pp.27-30
• /
• 1999

This experiment was carried out to determine the adequate machine peeling and retting time of peony roots, which are used as medicinal resources in Korea. When the roots were peeled for $10{\sim}30$ minitues in the peeling machine, the epidermis of root was removed, and higher yield was obtained and paeoniflorin content as compared with roots which were peeled for longer time. The paeoniflorin content of root varied with the different parts of root. The highest content was recorded in the upper part and the lowest in the middle part. The loss of paeoniflorin increased in the roots processed for expanded peeling and retting time. Lightness of peeled root was higher and ${\Delta}\;E$ was lower in the roots which were peeled by machine for longer time.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.9 no.6
• /
• pp.435-439
• /
• 2004

Three Bacillus strains were isolated from soil samples. Morphological and physiologi­cal characterization indicated that the isolated strains were B. mycoides, B. licheniformis and B. brevis. White pepper was produced from black pepper by the fermentative method using the isolates in shake flaks as well as in a large-scale fermenter. Volatile oil and piperine contents of the product were $3.2\%$ (v/w) and $4\%$ (v/w) respectively. The moisture content was $15\%$. The mi­crobial contamination was less than 10 per 100 g. The product also exhibited excellent storage stability.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1998.04a
• /
• pp.55-63
• /
• 1998

The fretting wear characteristics of Zircaloy-4 tube in light water were investigated experimentally. A fretting wear tester was designed to be suitable for this fretting test. This study was focused on the effects due to the combination of normal load, slip amplitude and number of cycles as the main factors of fretting. The results of this study showed that the wear volume increased abruptly at slip amplitude above 100$\mu$m, which is defined as critical slip amplitude of Zircaloy-4 tube in light water, and that under 160$\mu$m the wear volume decreased as load increased at the same slip amplitude.