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Interaction and the structures of coal.

Opaprakasit, Pakorn.

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Interaction and the structures of coal.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Interaction and the structures of coal./
作者:	Opaprakasit, Pakorn.
面頁冊數:	199 p.
附註:	Source: Dissertation Abstracts International, Volume: 64-07, Section: B, page: 3474.
Contained By:	Dissertation Abstracts International64-07B.
標題:	Engineering, Materials Science. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3098239

Interaction and the structures of coal.
Opaprakasit, Pakorn.

Interaction and the structures of coal. - 199 p.

Source: Dissertation Abstracts International, Volume: 64-07, Section: B, page: 3474.

Thesis (Ph.D.)--The Pennsylvania State University, 2003.

The origin of a decrease in the amount of soluble material from coal upon a reflux treatment has been investigated in an attempt to obtain insight into the nature of the interaction in the macromolecular network structure of coal. This decrease in the extractable material is a result of an increase in the amount of physical cross-links associated with secondary interactions. The alternate possibility of covalent cross-link formation by ether linkage was found to be unlikely because the coal hydroxyl content remains unchanged upon heat treatment. The functional groups responsible for forming these physical cross-links and their contents vary from coal to coal with coal rank. Carboxylate/cation complexes, similar to those found in ionomers, dominate in low rank coal. In high rank coal, the clusters involving pi-cation interactions were observed. Both mechanisms seem to play a role in mid rank coals. These physical cross-links are responsible for a lowering of the extraction yield of coal, but are disrupted by a treatment with acid solution, resulting in an increase in the extraction yield. As a consequence, the cross-links in coal structure should be classified into two types; a "permanent" covalent cross-link, which break under extreme conditions such as chemical reaction and pyrolysis, and "reversible" cross-links, largely associated with ionomer-like structure and pi-cation interactions.Subjects--Topical Terms:

1017759
Engineering, Materials Science.

Interaction and the structures of coal.
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245 1 0 $a Interaction and the structures of coal.
300 $a 199 p.
500 $a Source: Dissertation Abstracts International, Volume: 64-07, Section: B, page: 3474.
500 $a Adviser: Paul C. Painter.
502 $a Thesis (Ph.D.)--The Pennsylvania State University, 2003.
520 $a The origin of a decrease in the amount of soluble material from coal upon a reflux treatment has been investigated in an attempt to obtain insight into the nature of the interaction in the macromolecular network structure of coal. This decrease in the extractable material is a result of an increase in the amount of physical cross-links associated with secondary interactions. The alternate possibility of covalent cross-link formation by ether linkage was found to be unlikely because the coal hydroxyl content remains unchanged upon heat treatment. The functional groups responsible for forming these physical cross-links and their contents vary from coal to coal with coal rank. Carboxylate/cation complexes, similar to those found in ionomers, dominate in low rank coal. In high rank coal, the clusters involving pi-cation interactions were observed. Both mechanisms seem to play a role in mid rank coals. These physical cross-links are responsible for a lowering of the extraction yield of coal, but are disrupted by a treatment with acid solution, resulting in an increase in the extraction yield. As a consequence, the cross-links in coal structure should be classified into two types; a "permanent" covalent cross-link, which break under extreme conditions such as chemical reaction and pyrolysis, and "reversible" cross-links, largely associated with ionomer-like structure and pi-cation interactions.
520 $a The interaction between a "magic" solvent of N-methylpyrollidone and carbon disulfide (NMP/CS2) and its role in the unusual extractability enhancement of Upper Freeport coal has also been investigated. The results strongly suggest that NMP/CS2 mixed solvents form complexes with cations. These mixed solvents are capable of forming a solid complex with cations from NaOH and some simple salts, such as NaCl and LiCl. Given that Upper Freeport coal contains a large amount of mineral matter, it is not surprising that these types of complexes could be formed in the present of the mixed solvents, which in turn enhances the coal extraction yield.
520 $a Finally, the evidence for the presence of a glass transition temperature in coal was examined. The results from Differential Scanning Calorimetry showed that no transition similar to the Tg can be observed in bulk coal or its low-molecular weight fraction, pyridine soluble extracted material, at a temperature near 110°C. In contrast, an irreversible transition that is due to water evaporation has been found. Thermomechanical measurements, which are very sensitive to the presence of a Tg in synthetic polymers, also provided no evidence for a Tg below temperatures where chemical reactions occur. Additionally, the results from Thermomechanical Analysis showed an expansion in size when the coal was heated to 300°C, which is associated with a "caking" process.{09}The degree of expansion during this "caking" process is about five times greater in the direction perpendicular to the bedding plane than the parallel, indicating an accommodation of anisotropic strain relaxation, which was generated in the direction perpendicular to the bedding plane during the coalification process.
590 $a School code: 0176.
650 4 $a Engineering, Materials Science. $3 1017759
650 4 $a Chemistry, Polymer. $3 1018428
650 4 $a Geochemistry. $3 539092
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791 $a Ph.D.
792 $a 2003
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