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首页> 外文期刊>Journal of Applied Polymer Science >Effect of degree of deacetylation of chitosan on the kinetics of ultrasonic degradation of chitosan
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Effect of degree of deacetylation of chitosan on the kinetics of ultrasonic degradation of chitosan

机译：壳聚糖脱乙酰度对超声降解壳聚糖动力学的影响

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The objective of the study was to explore the effect of the degree of deacetylation (DD) of the chitosan used on the degradation rate and rate constant during ultrasonic degradation. Chitin was extracted from red shrimp process waste. Four different DD chitosans were prepared from chitin by alkali deacetylation. Those chitosans were degraded by ultrasonic radiation to different molecular weights. Changes of the molecular weight were determined by light scattering, and data of molecular weight changes were used to calculate the degradation rate and rate constant. The results were as follows: The molecular weight of chitosans decreased with an increasing ultrasonication time. The curves of the molecular weight versus the ultrasonication time were broken at 1-h treatment. The degradation rate and rate constant of sonolysis decreased with an increasing ultrasonication time. This may be because the chances of being attacked by the cavitation energy increased with an increasing molecular weight species and may be because smaller molecular weight species have shorter relaxation times and, thus, can alleviate the sonication stress easier. However, the degradation rate and rate constant of sonolysis increased with an increasing DD of the chitosan used. This may be because the flexibilitier molecules of higher DD chitosans are more susceptible to the shear force of elongation flow generated by the cavitation field or due to the bond energy difference of acetamido and beta-1,4-glucoside linkage or hydrogen bonds. Breakage of the beta-1,4-glucoside linkage will result in lower molecular weight and an increasing reaction rate and rate constant. (C) 2003 Wiley Periodicals, Inc. [References: 30]
机译：该研究的目的是探讨壳聚糖脱乙酰化程度（DD）对超声降解过程中降解速率和速率常数的影响。甲壳素是从红虾加工废料中提取的。由几丁质通过碱脱乙酰作用制备了四种不同的DD壳聚糖。这些壳聚糖通过超声辐射降解为不同的分子量。通过光散射确定分子量的变化，并且使用分子量变化的数据计算降解速率和速率常数。结果如下：壳聚糖的分子量随着超声时间的增加而降低。在1小时的处理中分子量与超声时间的关系曲线被破坏。随着超声时间的增加，声分解的降解速率和速率常数降低。这可能是因为随着分子量种类的增加，被空化能量攻击的机会增加，并且可能是因为较小的分子量种类具有较短的弛豫时间，因此可以更容易地减轻超声应力。然而，随着所用壳聚糖DD的增加，声分解的降解速率和速率常数也随之增加。这可能是因为较高DD壳聚糖的柔韧性分子更容易受到空化场产生的伸长流的剪切力的影响，或者是由于乙酰胺基和β-1,4-葡萄糖苷键或氢键的键能差。 β-1,4-葡萄糖苷键的断裂将导致分子量降低，反应速率和速率常数增加。 （C）2003 Wiley Periodicals，Inc. [参考：30]

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