• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.44 no.4
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• pp.43-50
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• 2012

The crystallinity index is an important characteristic of cellulose. The crystallinity value is different depending on the adopted instrument. In this study, we determined a crystallinity index of cotton and wood celluloses using wide-angle X-ray scattering (WAXS), powder X-ray diffractometer (PXRD), and cross polarization/magic angle spinning solid-state $^{13}C$ nuclear magnetic resonance spectroscopy (CP/MAS solid-state $^{13}C$ NMR). The specimen was prepared in forms of powder, sheet and pallet. With the comparison of the obtained crystallinity indices of the cellulose, the effects of the analysis instrument, the sample preparation and analysis method were investigated. Among three instruments, the crystallinity indices by PXRD and NMR had a good relationship and reproducibility, and WAXS gave the crystallinity index with poor reproducibility. In the case of analysis methods of crystallinity indices, the Segal method showed higher value than that of the Ruland-Vonk method. We expect that this study would be applicable to evaluate the crystallinity index of various cellulose materials with accuracy and reproducibility.

• Journal of the Korean Ceramic Society
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• v.33 no.7
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• pp.809-815
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• 1996

When Li2O.2SiO2 glass was crystallized between the temperature of maximum nucleation and the temperature of maximum crystal growth it was found that the control of heating rate had serious effect on the crystallinity and microstructure and the greatly changed physical properties. Density and elastic modulus tends to increase but thermal expansion coefficient decreased with increased crystallinity. When heating rate between the tempe-rature of maximum nucleation and the temperature of maximum crystal growth was 10~5$0^{\circ}C$/hr. crystallinity was increased to result in the increment of strength. When nuclation was done at 44$0^{\circ}C$ for 5 hours and the temperature of crystal growth was held at 575$^{\circ}C$ strength was increased until crystallinity reached 65% and strength was decreased with higher crystallinity. These phenomena could be explained that even for the same crystallinity different heat rates resulted in different number and size of cracks.

• International Journal of Industrial Entomology and Biomaterials
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• v.38 no.2
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• pp.51-55
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• 2019

The structure and properties of silk polymers (fibroin and sericin) can be satisfactorily controlled by choosing a suitable silkworm variety and, hence, this parameter (i.e., silkworm variety) has attracted increasing attention. A previous study reported that the crystallinity of white colored silkworm cocoons depends on the silkworm variety. In the present study, sixteen yellow colored silkworm variety cocoons were produced and their molecular conformation and crystallinity were investigated. The conformation of the silkworm cocoons varied with the silkworm variety. Most cocoons exhibited ${\beta}$-sheet conformation, although random coil and ${\beta}$-sheet conformations co-existed in some cocoons (e.g., 21 and D90). The crystallinity of the silkworm cocoons varied with the silkworm variety and the measurement position of the cocoon (i.e., outer surface or inner surface). However, the difference in the crystallinity indices of the outer and inner surfaces comprising the cocoons varied with the silkworm variety, but was <2% for all cocoons, except for MAL.

• International Journal of Industrial Entomology and Biomaterials
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• v.42 no.1
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• pp.7-13
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• 2021

In the present study, the effect of heat treatment on the crystallinity of the outside of silkworm cocoon in nine different silkworm varieties was studied using ATR-FTIR spectroscopy. Additionally, the morphological structure and moisture regain of the cocoon were examined. The silkworm cocoon showed different colors and external features depending on the silkworm variety. Moreover, the thickness of the filament (15.3-27.6 ㎛) and moisture regain of the cocoon (9.0%-11.0%) were quite different depending on the silkworm variety. The crystallinity index of the cocoon outside varied from 52.1% to 56.1%, depending on the silkworm variety. J300 and MO42 showed the highest (56.1%) and the lowest (52.1%) crystallinity index, respectively, indicating that the microstructure of sericin of the outside of the cocoon was affected by the silkworm variety. Regardless of silkworm variety, their crystallinity indexes decreased from 52.1%-56.1% to 49.9%-43.6% depending on the silkworm variety by the heat treatment at 250 ℃. Interestingly, the crystallinity degree decrease was somewhat different depending on the silkworm variety, implying that the cocoon sericin microstructure is strongly influenced by the silkworm variety.

• Journal of Biomedical Engineering Research
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• v.18 no.2
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• pp.107-112
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• 1997

The effect of gamma-irradiation sterilization on molecular structural changes in orthopaedic surgical-grade polyethylene was studied. The relative crystallinity ud. percent crosslinking of the substance increased as a result of the gamma irradiation and varied anisotropically as a function of depth. Samples from the articulating surfaces showed 5% Venter relative crystallinity than those from the mid-sections, whereas samples from the mid-sections exhibited 15% greater crosslinking than those from the surfaces. These anisotropic variations are discussed in assDciation with oxidation.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.4
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• pp.255-260
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• 1998

Behavior of solid phase crystallizations (SPC) of RF sputtered and LPCVD amorphous hydrogenated silicon film were investigated. LPCVD films showed the higher degree of crystallinity and larger grain size than sputtered films. The applicable degree of crystallinity was also obtained from sputtered films. The deposition method of amorphous silicon film influenced the behavior of post annealing SPC. Observed degree of crystallinity of sputtered films strongly depended on the partial pressure of hydrogen in deposition. The higher deposition temperature of sputtering provided the better crystallinity after SPC. Due to the high degree of poly-crystallinity, the retardation of larger grain growth was observed on sputtering film.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.5
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• pp.8-13
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• 2000

X-ray diffraction technique was used to quantify change of cellulose crystallinity during refining. XRD data confirmed that fiber wall delamination was caused by the structural conversion of celluloses which occurred in a liquid medium during refining. The quantified crystallinity of celluloses in pulp fibers was closely associated with the change of fiber wall delamination, which was defined by measurement of fiber wall thickness. In particular, it was well recognized that low intensity beating showed a better response in the change of crystallinity than high intensity one. The decrease o cellulose crystallinity during refining considerably enhanced the improvement of interfiber bonding ability of a dried sheet.

• International Journal of Industrial Entomology and Biomaterials
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• v.43 no.1
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• pp.16-21
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• 2021

The silkworm cocoon has recently attracted the attention of researchers because of its usefulness as a biomedical material (e.g., usage in the development of the membrane for guided bone regeneration and usage as a starting material for the fabrication of natural silk nonwoven fabric). The silkworm variety and strain have been reported as one of the important factors affecting the structure and properties of silk materials. This study examines the morphology and the molecular conformation of the silkworm cocoon at different cocoon measurement points, as well as the effect of the silkworm strain and rearing season on the morphology and crystallinity of the silkworm cocoon. The results show that the morphology of the outside of the cocoon does not differ depending on the cocoon measurement points, but that of the inside does. The silkworm cocoon crystallinity is not affected by the cocoon division. Interestingly, the crystallinity of the outside of the Jam101 cocoon differs depending on the rearing season, whereas it does not in other silkworm strains.

• International Journal of Industrial Entomology and Biomaterials
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• v.43 no.1
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• pp.22-28
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• 2021

Natural nonwoven silk fabric has attracted researchers' attention owing to its unique properties as a biomaterial. It is fabricated by reeling, wetting, and hot pressing natural silk filament from silkworm cocoons. In this study, silkworm cocoons were immersed in water at different temperatures for various durations to examine the effects of wet treatment on their crystallinity and morphology. As the treatment temperature and time increased, the cocoon's silk filament separation became more evident, and fibroin strands were observed in it. The crystallinity indexes of the silkworm cocoons increased until a treatment time of 2 h and remained constant thereafter. The increase in the crystallinity index using wet treatment was enhanced by increasing the treatment temperature. Although the weight loss of the silkworm cocoon was insignificant until 40℃, it was appreciable above this temperature, and the degree of weight loss constantly increased with increases in the treatment temperature and time.

• International Journal of Industrial Entomology and Biomaterials
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• v.38 no.1
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• pp.18-23
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• 2019

Bombyx mori silkworm has many silkworm varieties and the structure and properties of silk can be varied depending on the silkworm variety. Therefore, the choice of proper silkworm variety can be an effective way to control and improve the performance of silk materials in biomedical and cosmetic applications. As a preliminary study, in the present study, thirty nine Bombyx mori silkworm cocoons were prepared and their molecular conformation and crystallinity were examined. Molecular conformation and the crystallinity of silkworm cocoons were different depending on the silkworm variety. Interestingly, the crystallinity index of outside of cocoon was different from that of inside of cocoon and the difference between the crystallinities of outside and inside of cocoon was varied depending on the silkworm variety. In this study, the silkworm variety cocoons were classified into three groups (Group 1, Group 2, and Group 3) based on the difference of crystallinities between outside and inside.