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首页> 外文期刊>Journal of Applied Polymer Science >The effect of reaction time and temperature during heterogenous alkali deacetylation on degree of deacetylation and molecular weight of resulting chitosan
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The effect of reaction time and temperature during heterogenous alkali deacetylation on degree of deacetylation and molecular weight of resulting chitosan

机译：异碱脱乙酰反应时间和温度对脱乙酰度和壳聚糖分子量的影响

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摘要

The objective of the study is to elucidate the effect of reaction time and temperature during heterogenous alkali reaction on degree of deacetylation (DD) and molecular weight (MW) of the resulting chitosans, and to establish the reaction conditions to obtain desired DD and MW chitosan products. Chitin was extracted from red shrimp process waste. DDs and MWs were determined by infrared spectroscopy (IR) and static light scattering, respectively. The results are as follow: The DD and MW of chitin obtained were 31.9% and 5637 kDa, respectively. The DD of the resulting chitosan increased along with reaction time and/or reaction temperature. The DDs of the resulting chitosan that were obtained from 140degreesC were higher than those reacted at 99degreesC. The highest DD of the resulting chitosans after alkali deacetylation at 99 and 140degreesC were 92.2 and 95.1%, respectively. The DDs of chitosans increased fast at the beginning of reaction process then slowed over time. The reaction rate and rate constant of the deacetylation reaction decreased with increasing DD of the reactant. The MWs of chitosans decreased along with the deacetylation time. MW of those chitosans reacted at 140degreesC are smaller than those at 99degreesC. The rate of chitosan degradation was above 43.6%/h in the initial stage, then decreased to about 20%/h. The degradation rate constants raised substantially in the late stage. (C) 2003 Wiley Periodicals, Inc. [References: 51]
机译：该研究的目的是阐明异质碱反应过程中反应时间和温度对所得壳聚糖脱乙酰化度（DD）和分子量（MW）的影响，并建立反应条件以获得所需的DD和MW壳聚糖产品。甲壳素是从红虾加工废料中提取的。 DDs和MWs分别通过红外光谱（IR）和静态光散射确定。结果如下：获得的几丁质的DD和MW分别为31.9％和5637kDa。所得壳聚糖的DD随着反应时间和/或反应温度而增加。从140℃获得的壳聚糖的DDs高于在99℃反应的那些。在99和140℃进行碱脱乙酰后，所得壳聚糖的最高DD分别为92.2％和95.1％。壳聚糖的DDs在反应过程开始时快速增加，然后随着时间的过去而减慢。脱乙酰基反应的反应速率和速率常数随着反应物DD的增加而降低。壳聚糖的分子量随脱乙酰时间的延长而降低。 140℃下反应的那些壳聚糖的MW小于99℃下的那些。在初始阶段，壳聚糖的降解速率高于43.6％/ h，然后降至约20％/ h。降解速率常数在后期显着提高。 （C）2003 Wiley Periodicals，Inc. [参考：51]

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