Gel network structure of methylcellulose in water
Gel network structure of methylcellulose in water
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DOI：
10.1021/la010917r
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发表时间：
2001-12-25
期刊：
影响因子：
3.9
通讯作者：
Lam, YC
中科院分区：
文献类型：
--
作者：
Li, L;Thangamathesvaran, PM;Lam, YC
对甲基纤维素水凝胶溶液的热凝胶化进行了研究，试图阐明凝胶网络结构和结垢规律的有效性。加热时观察到热凝胶，冷却时恢复为液体状态。热可逆性是一个与加热/冷却速率相关的过程。对于等温稳定的样品，42.5℃是区分弱凝胶和强凝胶的临界温度。在42.5℃以下，凝胶弹性的演化遵循温度为G(c)的标度规律，类似于[(T - T-c)/T-c](2.93)，其中G(e)为凝胶的平衡模量，T-c为42.5℃的临界温度。而当温度高于42.5℃时，G(e)没有单一的标度规律。在42.5 ~ 70℃的温度范围内，弹性演化是温度的线性函数，结点间的平均桥长与温度无关。在实验结果的基础上，我们提出了由甲基纤维素形成的凝胶网络结构，该结构由疏水缔合结构域作为结，平均链长为2.75 x 10(4) g/mol作为连接结的桥。
Thermal gelation was studied for aqueous gelling solutions of a methyl cellulose, An attempt was made to elucidate the gel network structure and the validity of scaling laws. Thermal gelation was observed on heating, and it reverted to the liquid state on cooling. The thermoreversibility was a heating/cooling rate dependent process. For isothermally stabilized samples, 42.5 degreesC was found to be the critical temperature differentiating the weak gels from the strong gels. Below 42.5 degreesC, the gel elasticity evolved by following a scaling law with temperature as G(c) similar to [(T - T-c)/T-c](2.93) where G(e), is the equilibrium modulus of the gel and T-c is the critical temperature of 42.5 degreesC. In contrast, no single scaling laws could be found for G(e) when the temperature was above 42.5 degreesC. In the temperature range from 42.5 to 70 degreesC, it was observed that the elasticity evolution was a linear function of temperature and the mean bridge length between junctions was independent of temperature. On the basis of the experimental results, we proposed the gel network structure formed from the methylcellulose, which consists of hydrophobically associating domains as the junctions and the mean chain length of 2.75 x 10(4) g/mol as bridges connecting the junctions.