• Elastomers and Composites
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• 제46권3호
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• pp.186-194
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• 2011

셀룰로오스계 천연섬유인 kenaf를 천연고무와 함께 균일하게 배합한 후 압축성형 방법을 사용하여 천연섬유/천연고무 복합재료를 제조하였으며, 이들의 가황거동, 경도, 인장특성, 인열강도 및 정적, 동적 특성에 미치는 kenaf 섬유함량의 영향을 조사하였다. 복합재료를 구성하는 천연섬유의 함량은 천연고무 및 배합제 대비 0, 5, 10, 15, 20 phr이었다. 실험결과 천연고무의 여러 가지 특성이 kenaf 섬유의 함량에 의존한다는 것을 나타내었다. Kenaf 섬유함량이 증가함에 따라 천연고무의 가황에 요구되는 토크는 높아진 반면 가황시간은 감소되었다. Kenaf/천연고무 복합재료의 경도, 인장탄성률과 인열강도는 섬유함량이 증가할수록 점차적으로 증가한 반면, 인장강도와 파단신장률 은 감소하는 경향을 보여주었다. 또한 kenaf 섬유함량이 증가함에 따라 천연고무의 정적 특성보다는 동적 특성의 변화가 더욱 크게 나타났다. 고무에 가해지는 에너지의 감쇄 또는 흡수와 밀접한 관계가 있는 손실인자도 섬유함량에 비례하여 증가하였다.

• 방사선산업학회지
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• 제8권1호
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• pp.53-57
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• 2014

The kenaf is quickly developing as a renewable resource. Kenaf can be grown under a wide range of weather conditions. Modification of kenaf fiber by graft polymerization provides a significant route to alter the chemical properties, including surface hydrophilicity or hydrophobicity. In this study, kenaf fiber surfaces were grafted with acrylic acid as a hydrophilic group using electron beam irradiation. The grafting rate increased with an increase in grafting time. The FT-IR results confirmed that acrylic acid was successfully grafted onto the kenaf fibers. The wettability of the kenaf fiber was increased, accompanied by acylic acid grafting on the fiber surface. According to the permeability test result, it was found that acrylic acid grafted kenaf fiber reinforced cement composite was more reduced than non-grafted kenaf fiber reinforced cement composite.

• 한국의류학회지
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• 제27권7호
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• pp.862-871
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• 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.

• 한국의류학회지
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• 제30권7호
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• pp.1025-1033
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• 2006

Kenaf bast can be obtained by decortication of Kenaf stem. Kenaf fibers are much more rough than cotton fiber because they include impurities as pectin, lignin and hemicellulose besides cellulose. The purpose of this research is to investigate the distribution of kenaf fiber length and diameter during the processes of removing impurities. To remove pectin, kenaf bast was retted chemically. A half of the retted kenaf fiber bundle were scoured and bleached. The other half one were treated with $NaClO_2$ solution to remove lignin, and were treated with sodium hydroxide solution to remove hemicellulose. Four kinds of specimens that were obtained for investigating physical characteristics. Length and diameter of 100 fibers on each specimen was measured. The tensile strength of 100 fiber bundles were measured. And also the color values of them were measured with spectrocolorimeter. The length of retted kenaf fiber was 16.97cm. Then it decreased to 11.43cm after bleaching. Kenaf fiber bundles could be finer by chemical processes that remove non-cellulosic materials. The thickness of retted fiber was $132{\mu}m$. And after undergoing the chemical processes to remove non-cellulosic materials, the thickness of kenaf fiber became finer as $73{\mu}m$. Tensile strength of the retted kenaf fiber bundles was 11.37Mpa. The retted kenaf fiber lost their strength as 22.6% by bleaching and as 18.3% by treatment for removing lignin. The retted kenaf fiber showed low whiteness as 56.48 of L*value. After bleaching, the kenaf fibers have creamy white color and their whiteness got 90.02 of L*value. After the treatment for removing hemicellulose, the kenaf fibers also have creamy white color and their whiteness got L* value of 79.02.

• Carbon letters
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• 제12권3호
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• pp.131-137
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• 2011

Kenaf fibers, cellulose-based natural fibers, were used as precursor for preparing kenafbased carbon fibers. The effects of carbonization temperature ($700^{\circ}C$ to $1100^{\circ}C$) and chemical pre-treatment (NaOH and $NH_4Cl$) at various concentrations on the thermal change, chemical composition and fiber morphology of kenaf-based carbon fibers were investigated. Remarkable weight loss and longitudinal shrinkage were found to occur during the thermal conversion from kenaf precursor to kenaf-based carbon fiber, depending on the carbonization temperature. It was noted that the alkali pre-treatment of kenaf with NaOH played a role in reducing the weight loss and the longitudinal shrinkage and also in increasing the carbon content of kenaf-based carbon fibers. The number and size of the cells and the fiber diameter were reduced with increasing carbonization temperature. Morphological observations implied that the micrometer-sized cells were combined or fused and then re-organized with the neighboring cells during the carbonization process. By the pre-treatment of kenaf with 10 and 15 wt% NaOH solutions and the subsequent carbonization process, the inner cells completely disappeared through the transverse direction of the kenaf fiber, resulting in the fiber densification. It was noticeable that the alkali pre-treatment of the kenaf fibers prior to carbonization contributed to the forming of kenaf-based carbon fibers.

• 한국의류학회지
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• 제34권11호
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• pp.1889-1899
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• 2010

This study examines the preparation and characterization of Kenaf/Starch bio-composites used as filler and a matrix. Kenaf was cultivated in Chung-ju in Korea, and the Kenaf/Starch bio-composites were prepared under various conditions of kenaf fiber length (1-5 centimeters); the content of Kenaf fiber was 10%, 20%, 30%, and 40%, and the number of composite layers (one-four). Depending on the formation conditions of Kenaf/Starch composites, the physical properties such as tensile strength, elongation, and the young modulus of the Kenaf/Starch composites were measured. In addition, we measured the SEM cross-section images in order to investigate the interfacial adhesion properties of fractured surfaces. As a result, the tensile strength and elongation of the Kenaf/Starch composites were highest in the molding conditions of a hot press at $120^{\circ}C$, 3000PSI of pressure, and for 30 minute periods. The result of measuring the physical properties of the composites manufactured by varying the content of Kenaf fiber when the content of Kenaf fiber was 30% as well the physical properties of the Kenaf/Starch composite was found desirable. It was found that the physical properties improved with more overlapped layers in the composites manufactured by varying the number of overlapped layers. Through the measuring of the SEM cross-section images, we found that the interfacial adhesion state between the filler and matrix of Kenaf/Starch composite greatly affects the physical properties.

• 한국의류학회지
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• 제30권11호
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• pp.1581-1588
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• 2006

The effects of removal of lignin or hemicellulose on the cottonizing and pulping characteristics of kenaf fiber were studied by comparing the conditions of non-cellulosic material contents, fiber lengths and dyeability. And the effects of lignin or hemicellulose on dyeability of the kenaf fiber using CI Direct Green 26 and CI Direct Red 81 were investigated. The results were as follows. The lignin contents decreased and the kenaf fiber became shorter and finer as the reaction time with sodium chlorite increased. The hemicellulose could be removed by treating sodium hydroxide solution to the fiber from which the lignin partly removed. The 80% of hemicellulose could be removed by 5% of sodium hydroxide solution in 5 minutes. But if lignin were not removed at all, hemicellulose could not be removed. The fiber lengths proper for apparel were obtained after treating sodium chlorite for 10-20 minutes and those for pulping were obtained after treating sodium chlorite for 40 minutes. The kenaf fibers from which lignin and hemicellulose partly removed were dyed with CI Direct Green 26 and CI Direct Red 81. Their dyeability increased as the removal rates of lignin increased. The ${\Delta}E$ values of kenaf fiber dyed with CI Direct Green 26 were lower than CI Direct Red 81.

• Journal of the Korean Wood Science and Technology
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• 제37권3호
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• pp.222-230
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• 2009

본 연구에서는 천연 섬유와 matrix간의 결합에 불리하게 작용하는 wax, lignin, hemicellulose 등을 제거하기 위한 방법 중 하나인 NaOH를 이용한 천연섬유의 알칼리 처리가 Kenaf 장섬유/PP 혼합 바이오복합재 제조 시 계적인 물성에 미치는 영향에 대해 알아보았다. Kenaf 장섬유의 적절한 배합비와 알칼리처리를 통한 최적의 바이오복합재를 제조하기 위하여 알칼리 처리 시의 농도와 kenaf fiber의 함유량을 달리하여 각 처리조건에 따른 바이오복합재의 특성을 조사하였다. 알칼리 처리를 통한 계면 결합의 증가를 확인하기 위하여 SEM을 이용하여 복합재의 단면을 확인하였다. 그 결과 알칼리 처리가 3% 농도부터 계면 결합이 증가하고, 5%일 때의 최고의 계면 결합력을 보였다. 하지만 기계적 강도에서는 알칼리 농도 3% 처리한 것이 최적이었으며 kenaf fiber가 30% 함유된 PP/kenaf섬유 바이오복합재가 높은 강도를 나타내었다.

• 한국의류학회지
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• 제28권7호
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• pp.873-881
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• 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.

• 한국의류학회지
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• 제27권9_10호
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• pp.1144-1152
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• 2003

Kenaf has been cultivated in Jeju Island. After being harvested at 105 DAP(day after planting) and separated from kenaf stalks , decorticated kenaf basts were treated with different concentration/temperature/time combinations in order to do chemical rotting. The following fiber properties were compared; rotting effects, colors, crystallinity, molecular structures, dyeabilities, and non-cellulose contents such as pectins, lignins, & hemicellulose. The best results of chemical rotting were obtained from the specimens treated with low concentration/ low temperature/short time. Their colors were bright yellow. The lumens of specimens diminished with the affect of NaOH. The structures of chemically rotted kenaf fibers were cellulose 1. The degree of crystallinity of chemically retted kenaf fibers were very high. Non-cellulose content, especially hemicellulose, was low in the specimens treated with the high NaOH concentration. Dyeabilities of kenaf fibers were higher among the specimens without the non-cellulose content than those with the non-cellulose content.