長鏈二羧酸 的英文怎麼說
中文拼音 [zhǎngliànèrsuōsuān]
長鏈二羧酸
英文
long chain dicarboxylic acid-
Abstract : methanesulfonic acid method was used to prepare five acylated chitins. except heptanoyl chitin, four of them, i. e. acetyl chitin, propionyl chitin, butyryl chitin and hexanoyl chitin, had high degree of substitution ( from 1. 5 to 2. 0 ) and exhibited lyotropic liquid crystalline behavior and cholesteric phase. as the length of the side chain increased the critical concentration ( w / w ) somewhat increased from 0. 21 to 0. 26 because the chain rigidity dropped. the critical concentration values of all the four derivatives were much higher than that of chitin ( 0. 12 ) due to the decrease of intramolecular hydrogen bonds. the four acylated chitin can form typical banded texture after being sheared. there minimum concentrations to form banded texture of them were evidently different, varied from 0. 25 ( for acetyl chitin ) to 0. 37 ( for hexanoyl chitin ). these results further indicated that liquid crystallinity decreased while the length of flexible side substituents increased
文摘:四種羧酰化甲殼素即乙酰化、丙酰化、丁酰化和己酰化甲殼素在二氯乙酸溶液中均呈現膽甾型溶致液晶相.臨界濃度隨側基長度增加而略有增加,衍生物的臨界濃度明顯都比原甲殼素高許多,這些規律都可以用鏈剛性的變化來解釋.四種羧酰化甲殼素在剪切時均能形成條帶織構,而且能形成條帶織構的最低濃度有明顯差別,隨側基長度增加而提高,進一步表明側基較長,液晶性減少Phenyl group introducing to cholesteryl ester molecules can enhance the phase transition temperatures of the liquid crystals and their stability. an increase in the chain length for cholesteryl dicarboxylate samples reduced stability of liquid crystal phases. while coattail - like structures on the ester group of the molecules have an adverse effect to form cholesteryl liquid crystal phase
化學結構對液晶性的影響表現為:分子中引入苯環剛性結構可以提高液晶的相變溫度和穩定性;脂族二羧酸膽甾醇酯中脂肪鏈的長度增加會降低液晶的穩定性;而末端含有燕尾結構則對液晶態的形成產生不利影響。
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