International Journal of Industrial Entomology and Biomaterials

Korean Society of Sericultural Science (한국잠사학회)
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Effect of heat treatment on the structural characteristics and properties of silk sericin film

  • Park, Chun Jin (Department of Biofibers and Biomaterials Science, Kyungpook National University) ;
  • Um, In Chul (Department of Biofibers and Biomaterials Science, Kyungpook National University)
  • Received : 2018.11.18
  • Accepted : 2018.11.28
  • Published : 2018.12.31
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Abstract

Recently, silk sericin has attracted attention because of its unique properties as a biomaterial, including its UV resistance, moisturizing effect on skin, and wound-healing effect. Therefore, the preparation of sericin in various forms such as gel, film, fiber, and sponge is studied for cosmetic and biomedical applications, and the effect of the preparation conditions on the structure and properties of sericin forms is examined to maximize its performance. In this study, silk sericin films were prepared under different preparation conditions and heat-treated at high temperatures ($100-250^{\circ}C$) to examine the effect of heat treatment on the film structure. The order of the crystallinity index of the untreated sericin film is as follows: F25 (sericin film cast from formic acid) > WE25 (ethanol treated sericin film cast from water at $250^{\circ}C$) > W25 (sericin film cast from water at $250^{\circ}C$) > W100 (sericin film cast from water at $100^{\circ}C$). As the heat-treatment temperature was increased, the color of the sericin films changed gradually from colorless to yellow, brown, and black depending on the temperature. The crystallinity of the sericin film changed after the heat treatment, depending on the preparation condition. Whereas a sericin film cast from formic acid (F25) started to lose its crystallinity at $200^{\circ}C$, thus undergoing the highest loss of crystallinity among the sericin films studied, the rest (W25, WE25, and W100) showed a decrease in crystallinity at $250^{\circ}C$, owing to the disruption of the ${\beta}$-sheet crystallites due to heat.

Keywords

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Fig. 1. Effect of heat treatment on the FTIR spectrum of sericin film W100

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Fig. 2. Effect of heat treatment on the FTIR spectrum of sericin flm W25

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Fig. 4. Effect of heat treatment on the FTIR spectrum of sericin flm F25

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Fig. 5. Effect of heat treatment on the crystallinity index of sericin films prepared under different conditions.

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Fig. 3. Effect of heat treatment on the FTIR spectrum of sericin film WE25

Table 1. Preparation conditions for obtaining silk flms with different crystallinity index

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Table 2. Effect of treatment temperature on the color and shape of sericin flms prepared under different conditions

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References

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