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Title: Variation of nanostructures, molecular interactions, and anisotropic elastic moduli of lignocellulosic cell walls with moisture

Source: Scientific Reports. 7(1): 1-10.

Author(s)Youssefian, S.; Jakes, J. E.; Rahbar, N.

Publication Year: 2017  View PDF »

Category: Journal Articles
Associated Research Project(s):   FPL-4707-2B

Abstract: A combination of experimental, theoretical and numerical studies is used to investigate the variation of elastic moduli of lignocellulosic (bamboo) fiber cell walls with moisture content (MC). Our Nanoindentation results show that the longitudinal elastic modulus initially increased to a maximum value at about 3% MC and then decreased linearly with increasing MC. In contrast, the transverse moduli decrease linearly with MC. We showed that amorphous materials in cell walls have key roles in the variation of elastic modulus with increasing MC. Elastic modulus of lignin, calculated by molecular dynamics simulations, increases initially with increasing MC, and then decreases. In contrast, elastic modulus of hemicellulose decreases constantly with MC. Below 10% MC, water molecules tend to break hydrogen bonds between polymer chains and form new hydrogen bond bridges between the polymer chains, while above 10% MC, water molecules aggregate together and create nano-droplets inside the materials. During the process of bridging, the fractional free volume of lignin decreases. The free volume reduction along with formation of hydrogen bond bridges causes a growth in elastic modulus of lignin at low MC. The constant increase of hemicellulose free volume, however, causes the aggregation of voids in the system and diminution of elastic properties.

Keywords: Cell wall; atomistic simulations; nanoindentation

Publication Review Process: Formally Refereed

File size: 2,048 kb(s)

Date posted: 10/06/2017

This publication is also viewable on Treesearch:  view
RITS Product ID: 88444
Current FPL Scientist associated with this product
Jakes, Joseph
Research Materials Engineer
  

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