Gel transition studies on nonideal polymer networks using small amplitude oscillatory rheometry
Gel transition studies on nonideal polymer networks using small amplitude oscillatory rheometry
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DOI：
10.1122/1.550929
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发表时间：
1998-09-01
影响因子：
3.3
通讯作者：
Boger, DV
中科院分区：
文献类型：
--
作者：
Power, DJ;Rodd, AB;Boger, DV
羟丙基瓜尔胶（HPG）在硫酸根离子存在下容易形成物理凝胶。讨论了凝胶的性质，重点讨论了硼酸盐交联HPG在结构转变点的流变性。由Winter和Chambon（1986）开发的凝胶点表征方法可用于确定从液体行为到具有永久交联位点的真正化学网络的确切转变点。该技术已应用于上述HPG体系，其交联位点（或接合区）处于pH活化的动态平衡。通过对溶液转变不同阶段的损耗模量的分析，提出了一种确定硼酸盐交联HPG溶液/凝胶转变的方法。观察到损耗模量的最大值非常接近于使用Winter和Chambon的方法确定的凝胶转变。研究了聚合物和交联剂浓度对稳定凝胶性能的影响。凝胶点松弛指数n在0.14和0.5之间变化，取决于构成凝胶网络的物质的浓度。从这两种流变技术的结果，以及讨论各自的局限性。对于所有流变测量，使用恒定应变Weissenberg流变仪进行小振幅振荡测量。(C)1998年，流变学学会。
Hydroxypropylguar (HPG) readily forms a physical gel in the presence of berate ions. A discussion of gel properties is given, with emphasis on the rheological properties of berate crosslinked HPG at the structural transition point. A gel point characterization method developed by Winter and Chambon (1986) may be used to define the exact point of transition from liquid behavior to that of a true chemical network with permanent crosslink sites. This technique has been applied to the HPG system described above whose crosslink sites (or junction zones) are at a pH activated dynamic equilibrium. Analysis of the loss modulus at different stages of the solution transition presents a method for establishing the solution/gel transition of berate crosslinked HPG. A maximum in the loss modulus is observed to correspond very closely to the gel transition determined using the method of Winter and Chambon. The steady gel properties of the fluid are studied as a function of the concentration of both the polymer and the crosslinking species. The gel point relaxation exponent n varies between 0.14 and 0.5, depending on the concentration of the species which constitute the gel network. Results from both rheological techniques are presented as well as a discussion of their respective limitations. Small amplitude oscillatory measurements are performed using a constant strain Weissenberg rheogoniometer for all rheological measurements. (C) 1998 The Society of Rheology.