Kasaai Mohammad R, Arul Joseph, Charlet Gérard
Faculty of Agricultural Engineering, Mazandaran University, Khazar Abad Road, Km. 9, P.O. Box 578, Sari, Mazandaran, Iran.
Ultrason Sonochem. 2008 Sep;15(6):1001-8. doi: 10.1016/j.ultsonch.2008.04.005. Epub 2008 Apr 25.
Kinetics of chitosan fragmentation by ultrasonic irradiation at frequency of 20 kHz, and the effects of experimental variables (power of ultrasound, chitosan concentration and solution temperature) on fragmentation were investigated. The kinetics studies were followed by measuring solution viscosity of the original and its fragments, and determining average number of chain scission of the fragments. The effects of ultrasonic power, chitosan concentration and solution temperature on fragmentation process were followed by viscometry and size exclusion chromatography. The chemical structure of the original chitosan and its fragments were examined by (1)H NMR spectroscopy and elemental analysis. The experimental results showed that the rate of fragmentation increased with an increase in power of ultrasound. Chain scission increased with an increase in power of ultrasound; and solution temperature, but a decrease in chitosan concentration. The chemical structure and polydispersity of the original and the fragments were nearly identical. A model based on experimental data to describe the relationship between chain scission and experimental variables (power of ultrasound; irradiation time; reduced concentration, c[eta]; and solution temperature) was proposed. It was concluded that ultrasonic irradiation is a suitable method to perform partial depolymerization and to obtain moderate macromolecules from large ones.
研究了20kHz频率超声辐照下壳聚糖的碎片化动力学，以及实验变量（超声功率、壳聚糖浓度和溶液温度）对碎片化的影响。动力学研究通过测量原液及其碎片的溶液粘度，并确定碎片的平均断链数来进行。通过粘度测定法和尺寸排阻色谱法研究了超声功率、壳聚糖浓度和溶液温度对碎片化过程的影响。通过¹H NMR光谱和元素分析对原始壳聚糖及其碎片的化学结构进行了检测。实验结果表明，碎片化速率随超声功率的增加而增加。断链随超声功率、溶液温度的增加而增加，但随壳聚糖浓度的降低而增加。原始壳聚糖及其碎片的化学结构和多分散性几乎相同。提出了一个基于实验数据的模型，以描述断链与实验变量（超声功率、辐照时间、比浓粘度c[η]和溶液温度）之间的关系。得出的结论是，超声辐照是一种进行部分解聚并从大分子中获得中等大小分子的合适方法。
