κ-卡拉胶热可逆凝胶化行为研究

用固体小角激光散射方法研究κ 卡拉胶 (KC)的热可逆凝胶化行为 .以散色斑点的突停点温度为体系的凝胶化点Tgel,考察了溶液中加入Na+ ,K+ ,NH+4,Ca2 + ,Cu2 + ,Zn2 + 等抗衡离子对Tgel的影响 .结果是随抗衡离子浓度增大Tgel上升 ;Tgel与Na+ 的浓度呈线性关系 ,与K+ ,NH+4,Ca2 + ,Cu2 + ,Zn2 + 等离子浓度的平方根成线性关系 ;另外 ,还得到 30℃时KC在KCl盐溶液中的溶胶 凝胶相图 ,并对比了KC在NaCl溶液中透析前后Tgel的变化 .

A STUDY OF THERMOREVESIBLE GELATION OF κ-CARRAGEENAN BY SMALL ANGLE LASER LIGHT SCATTERING

The thermoreversible gelation of κ-carrageenan (KC)was studied by small angle laser light scattering(SALLS).The mobility of random fluctuation of scattering speckles is used to detect the sol-gel transition,and the mobility disappears suddenly at a point during the cooling process of KC solutions.The temperature at that point is designed as gelation point (T gel).Effects of several counterions,including Na+,K+,NH+ 4,Ca 2+,Cu 2+ and Zn 2+,on T gel were determined.Although all ions are able to promote the gelation of KC,the promoting ability can be ranged to three regions:K+,NH+ 4 (I),Ca 2+,Cu 2+,Zn 2+(II) and Na+(III),their promoting abilities have the following sequence:I>II>III. T gel is found to be proportional to the square root of concentrations of conterions,except Na+.The influence of KC concentration on T gel in NaCl and KCl aqueous solutions also shows the promoting abilities of both Na+ and K+ ions.Furthermore,the phase diagram of KC-KCl aqueous solutions at 30℃ was obtained.The comparison of T gel values for KC-NaCl solutions before and after dialysis further reveals the promoting function of Na+ ions,and some controversial results in literature concerning the function of Na+ ions are supposed to result from the different methods used for T gel determination.