critical chain length 中文意思是什麼
critical chain length
解釋
臨界鏈長-
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 -
The urea - formaldehyde ( uf ) polymer / sio2 composite microspheres were prepared by polymerization - induced colloid aggregation ( pica ) method. the formation mechanism of composite microspheres is attributed to the fact that that urea and formaldehyde firstly undergo acid - catalyzed polymerization to form oligomers, and then the sol particles are adsorbed on the chain of oligomers by wan der walls force and hydrogen bonding. when the oligomers reach the critical chain length, they separate from solution due to phase separation
對復合微球形成機理的研究表明，尿素和甲醛在酸性條件下自身聚合可以形成高分子微球，在sio _ 2酸性溶膠中發生聚和反應時，隨著反應的進行，齊聚物不斷生成， sio _ 2膠體顆粒逐漸吸附在齊聚物分子鏈上，當聚合物鏈達到沉澱臨界鏈長時，由於相分離作用，從前驅物溶液中析出，同時sio _ 2膠體顆粒均勻的分佈在脲醛聚合物網路中，隨之沉澱出來，形成脲醛sio _ 2復合微球。
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