The chain microstructure and condensed structure of polyethylene resin used for Biaxially stretched film

2020 ◽  
Vol 138 (2) ◽  
pp. 49652 ◽  
Author(s):  
Yu Li ◽  
Binbo Jiang ◽  
Wei Li ◽  
Jingdai Wang ◽  
Yongrong Yang
Keyword(s):  
Condensed Structure

scholarly journals A Comparison of Ethylene-Tar-Derived Isotropic Pitches Prepared by Air Blowing and Nitrogen Distillation Methods and Their Carbon Fibers

Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 305 ◽  
Author(s):  
Kui Shi ◽  
Jianxiao Yang ◽  
Chong Ye ◽  
Hongbo Liu ◽  
Xuanke Li
Keyword(s):  
Tensile Strength ◽  
Carbon Fibers ◽  
Melt Spinning ◽  
Raw Material ◽  
Bridge Structure ◽  
Aromatic Rings ◽  
Aromatic Molecules ◽  
Structures And Properties ◽  
Air Blowing ◽  
Condensed Structure

Two isotropic pitches were prepared by air blowing and nitrogen distillation methods using ethylene tar (ET) as a raw material. The corresponding carbon fibers were obtained through conventional melt spinning, stabilization, and carbonization. The structures and properties of the resultant pitches and fibers were characterized, and their differences were examined. The results showed that the introduction of oxygen by the air blowing method could quickly increase the yield and the softening point of the pitch. Moreover, the air-blown pitch (ABP) was composed of aromatic molecules with linear methylene chains, while the nitrogen-distilled pitch (NDP) mainly contained polycondensed aromatic rings. This is because the oxygen-containing functional groups in the ABP could impede ordered stack of pitch molecules and led to a methylene bridge structure instead of an aromatic condensed structure as in the NDP. Meanwhile, the spinnability of the ABP did not decrease even though it contained 2.31 wt % oxygen. In contrast, the ABP had narrower molecular weight distribution, which contributed to better stabilization properties and higher tensile strength of the carbon fiber. The tensile strength of carbon fibers from the ABP reached 860 MPa with fiber diameter of about 10 μm, which was higher than the tensile strength of 640 MPa for the NDP-derived carbon fibers.

Ozone Oxidation and Structural Features of an Almond Shell Lignin Remaining after Furfural Manufacture

Holzforschung ◽  
2002 ◽  
Vol 56 (1) ◽  
pp. 32-38 ◽  
Author(s):  
J. Quesada ◽  
F. Teffo-Bertaud ◽  
J.P. Croué ◽  
M. Rubio
Keyword(s):  
Aromatic Aldehydes ◽  
Structural Features ◽  
Raw Material ◽  
Added Value ◽  
Industrial Processes ◽  
Ozone Treatment ◽  
Almond Shell ◽  
Condensed Structure ◽  
Ferulic Acids ◽  
G Ratio

Summary Wastes from industrial processes which use lignocellulosic materials as raw material are an interesting source of chemicals since they can be transformed into products of high added value. In the process described here, ozone was used to produce oxyaromatics from a lignin-rich industrial waste resulting from the production of furfural from almond shells. Ozonation, thioacidolysis and mild alkaline hydrolysis were used to determine some structural features of the raw and acid-hydrolyzed almond shell lignins. During ozone treatment of the different lignin solutions the following compounds were identified: glycolic, oxalic, malonic, glyceric (trace), malic, p-hydroxybenzoic and vanillic acids, p-hydroxybenzaldehyde, vanillin, syringaldehyde and hydroquinone. The aromatic aldehydes passed through a production maximum during the first few minutes of the reaction, while glycolic and oxalic acid (the main aliphatic acids) yields increased throughout the treatment. Raw almond shell lignin had a typical hardwood composition [made up of guaiacyl (G) and syringyl (S) phenylpropane units] and few β-O-4 structures. Acid-hydrolyzed almond shell lignins had a more condensed structure than the above. The S/G ratio obtained by ozonation was slightly lower than that obtained by thioacidolysis, with the (S/G)Ozonation/(S/G)Thioacidolysis ratio ranging from 0.52 to 0.70. The almond shell lignin-polysaccharide complex did not contain any cell wall-esterified p-hydroxycinnamic acid (p-coumaric and ferulic acids).

scholarly journals A Comparison of Ethylene Tar-Derived Isotropic Pitches Prepared by Air Blowing and Nitrogen Distillation Method and Their Carbon Fibers

2018 ◽  
Author(s):  
Kui Shi ◽  
Jianxiao Yang ◽  
Chong Ye ◽  
Hongbo Liu ◽  
Xuanke Li
Keyword(s):  
Tensile Strength ◽  
Carbon Fibers ◽  
Melt Spinning ◽  
Raw Material ◽  
Distillation Method ◽  
Aromatic Rings ◽  
Aromatic Molecules ◽  
Structures And Properties ◽  
Air Blowing ◽  
Condensed Structure

Two isotropic pitches were prepared by air blowing and nitrogen distillation method using ethylene tar (ET) as a raw material. And correspondent carbon fibers were obtained through conventional melt spinning, stabilization and carbonization. The structures and properties of resultant pitches and fibers were characterized and their differences were discussed in this work. The results showed that introduction of the oxygen by air blowing method could quickly increase the yield and softening point of pitch. Moreover, the air blown pitch (ABP) composed of linear methylene chains of aromatic molecules while the nitrogen distilled pitch (NDP) mainly contained polycondensed aromatic rings, which was due to the oxygen containing functional groups existed in ABP could impede order stack of pitch molecules and form methylene bridge structure, instead of aromatic condensed structure like NDP. Meanwhile, the spinnability of ABP was not decreased even containing 2.31 wt% oxygen. In contrast, ABP had narrower molecular weight distribution, which contributed to better stabilization properties and higher tensile strength of carbon fiber. The tensile strength of carbon fibers from ABP was reached to 860 MPa with fiber diameter of about 10 μm, which was higher than that of NDP-derived carbon fibers of 640 MPa.

scholarly journals Changing the Overall Shape of Heterodinuclear Helicates via Substitution of Acylhydrazones by Tosylhydrazones

2010 ◽  
Vol 65 (3) ◽  
pp. 311-316 ◽  
Author(s):  
Markus Albrecht ◽  
Irene Latorre ◽  
Yufeng Liu ◽  
Roland Fröhlich
Keyword(s):  
Condensed Structure

Heterodinuclear helicate-type complexes are formed from acyl and tosyl hydrazone-substituted catechol ligands. Due to the different geometry of the carboxylate compared to the sulfonate unit, different overall structures are observed for the complexes. The acylate results in the formation of a cylindrical triple-stranded system, while in the tosylate the pendant substituents fold back and form a more condensed structure.

Condensed structure of J = T = 0 α-like clusters in even-even nuclei with N = Z

1995 ◽  
Vol 592 (1) ◽  
pp. 45-58 ◽  
Author(s):  
M. Hasegawa ◽  
S. Tazaki ◽  
R. Okamoto
Keyword(s):  
Condensed Structure

scholarly journals SIR proteins create compact heterochromatin fibers

2018 ◽  
Vol 115 (49) ◽  
pp. 12447-12452 ◽  
Author(s):  
Sarah G. Swygert ◽  
Subhadip Senapati ◽  
Mehmet F. Bolukbasi ◽  
Scot A. Wolfe ◽  
Stuart Lindsay ◽  
...  
Keyword(s):  
Genomic Stability ◽  
Histone H4 ◽  
Complicated Structure ◽  
Force Microscopy ◽  
Structure And Dynamics ◽  
Sir Proteins ◽  
Atomic Force ◽  
Condensed Structure ◽  
Chromatin Fibers ◽  
Heterochromatin Assembly

Heterochromatin is a silenced chromatin region essential for maintaining genomic stability and driving developmental processes. The complicated structure and dynamics of heterochromatin have rendered it difficult to characterize. In budding yeast, heterochromatin assembly requires the SIR proteins—Sir3, believed to be the primary structural component of SIR heterochromatin, and the Sir2–4 complex, responsible for the targeted recruitment of SIR proteins and the deacetylation of lysine 16 of histone H4. Previously, we found that Sir3 binds but does not compact nucleosomal arrays. Here we reconstitute chromatin fibers with the complete complement of SIR proteins and use sedimentation velocity, molecular modeling, and atomic force microscopy to characterize the stoichiometry and conformation of SIR chromatin fibers. In contrast to fibers with Sir3 alone, our results demonstrate that SIR arrays are highly compact. Strikingly, the condensed structure of SIR heterochromatin fibers requires both the integrity of H4K16 and an interaction between Sir3 and Sir4. We propose a model in which a dimer of Sir3 bridges and stabilizes two adjacent nucleosomes, while a Sir2–4 heterotetramer interacts with Sir3 associated with a nucleosomal trimer, driving fiber compaction.

Sign in / Sign up

Export Citation Format

Share Document