دانلود رایگان مقاله تقویت کننده خواص پلی استر باکتریایی با نانوبلور سلولز با تغییر پیوند هیدروژنی

Abstract

This work provides a direct evidence to investigate relationship between hydrogen bonding interactions and property enhancement of cellulose nanocrystals (CN) based bionanocomposites. Cellulose nanocrystal citrates (CNsingle bondC) with more hydroxyl (Osingle bondH) and carboxyl groups, CN and cellulose nanocrystal formates (CNsingle bondF) with less Osingle bondH groups were extracted from commercial microcrystalline cellulose using citric/hydrochloric acids, hydrochloric acid and formic/hydrochloric acids, respectively. Then different nanocrystals were incorporated into bacterial polyester poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) for tuning hydrogen bonding interactions and properties of PHBV nanocomposites. As expected, at the same loading contents, CNsingle bondC had stronger reinforcing capability on PHBV matrix than CN and CNsingle bondF. Compared to neat PHBV, tensile strengths of 10% CNsingle bondF/PHBV, 10% CN/PHBV and 10% CNsingle bondC/PHBV were improved by 146%, 166% and 187%, respectively. Especially, the maximum decomposition temperature of 10% CNsingle bondC/PHBV was increased by 48.1 °C, and this nanocomposite showed superior barrier properties with a 64% reduction in water vapour permeability (WVP). Besides, the nanocomposites showed excellent biocompatibility to human MG-63 cells and lower overall migration levels. Such an outstanding reinforcement by CNsingle bondC was ascribed to improved interfacial interaction (more hydrogen bonding interactions or hydrogen bond network), and nanodispersibility in the nanocomposites.

4. Conclusions

CNPs with different surface groups (CNeF, CN and CNeC) were successfully prepared and used as reinforcement materials for PHBV nanocomposites. It confirms that at good dispersion state of nanofillers, CNeC with more OeH groups could form more intermolecular hydrogen bonds with PHBV matrix. As a result, at the same loading level, greater improvements in the mechanical and thermal properties were found compared to other nanocomposites. Compared with neat PHBV, tensile strengths and Tmax of 10% CNeC/ PHBV were improved by 187% and 48.1
C, respectively. The nanocomposites showed a 64% reduction in water vapour permeability (WVP) indicating stronger reinforcing capability on PHBV matrix than CN and CNeF. This could be due to stronger interactions (more hydrogen bonds or hydrogen bond network) and their good nanoparticle dispersion. Moreover, overall migration levels of 10%CNeC/PHBV were well below the migration limits for food contact materials and showed excellent biocompatibility to human MG-63 cells. This study provides a method to modulate hydrogen bonding interaction and properties of PHBV nanocomposites, meanwhile the obtained nanocomposites have charming application in food biopackaging materials.