Theoretical Study of Size Effects on Surface Chemical Properties for Nanoscale Diamond Particles

2014 ◽  
Vol 118 (45) ◽  
pp. 26061-26069 ◽  
Author(s):  
Tian Yuan ◽  
Karin Larsson
Keyword(s):  
Size Effects ◽  
Theoretical Study ◽  
Chemical Properties ◽  
Surface Chemical ◽  
Diamond Particles

Effect of High-Temperature Defibration on the Chemical Structure of Hardwood

Holzforschung ◽  
2002 ◽  
Vol 56 (1) ◽  
pp. 51-59 ◽  
Author(s):  
P. Widsten ◽  
J.E. Laine ◽  
P. Qvintus-Leino ◽  
S. Tuominen
Keyword(s):  
High Temperature ◽  
Lignin Content ◽  
Bulk Composition ◽  
Chemical Properties ◽  
Water Extract ◽  
Fiber Surface ◽  
Phenolic Hydroxyl ◽  
Hydroxyl Groups ◽  
Surface Chemical ◽  
Alkyl Aryl

Summary The present paper aims at elucidating the effect of high-temperature defibration at different temperatures on the bulk and surface chemical properties of defibrated birch, aspen and eucalypt. The results indicate that defibration of these hardwoods results in partial depolymerization of fiber lignin via (homolytic) cleavage of interunit alkyl-aryl (β-O-4) ether bonds. This increases the phenolic hydroxyl content and produces relatively stable (phenoxy) radicals. Syringyl-type lignin is more extensively depolymerized than guaiacyl-type lignin. Defibration generates water-extractable material, which is enriched in hemicellulose-derived carbohydrates and has a substantial content of aromatic compounds rich in phenolic hydroxyl groups. The amount of water-extract and the extent of lignin interunit ether bond cleavage increase with an increase in defibration temperature. The differences between various hardwood species in this respect are small. The surface chemical composition of the fibers differs considerably from their bulk composition, but is not significantly influenced by variations in defibration temperature. Lipophilic extractives cover a large portion of the fiber surface, while the lignin content of lipophilic extractives-free fiber surfaces is 2–3 times as high as the bulk lignin content of the fibers.

scholarly journals Vibrational spectra and physico-chemical properties of astrophysical analogs

2017 ◽  
Vol 19 (39) ◽  
pp. 26582-26588 ◽  
Author(s):  
Pedro C. Gómez ◽  
Rafael Escribano
Keyword(s):  
Vibrational Spectra ◽  
Theoretical Study ◽  
Chemical Properties ◽  
Amorphous Solids ◽  
Physico Chemical

We undertake in this paper a theoretical study based on DFT methodology of amorphous solids formed by methane, water and nitrogen in a ratio of 1 : 3 : 3.

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