Yu D M, Amidon G L, Weiner N D, Goldberg A H
College of Pharmacy, University of Michigan, Ann Arbor 48109-1065.
J Pharm Sci. 1994 Oct;83(10):1443-9. doi: 10.1002/jps.2600831016.
The viscoelastic properties of poly(ethylene oxide) (PEO) solution were investigated using the dynamic oscillatory testing technique. With this technique, the effect of PEO molecular weight (MW), concentration, composition of mixed solvent systems consisting of propylene glycol, glycerol formal, and water, and the effect of NaCl salt on the viscoelastic properties of PEO solution were determined. Dynamic moduli (G1, G2), magnitude of complex viscosity (magnitude of eta*), and loss tangent (tan delta) were examined over a frequency range of 10(-3)-2.5 Hz at 30 degrees C. The results indicated that low MW PEOs show liquidlike behavior while high elasticity is exhibited by high MW PEOs due to entanglement formation. The complex viscosity, magnitude of eta*, exhibits shear thinning (power-law) characteristics under oscillatory measurements. The relationship between steady shear and complex viscosities follows the Cox-Merz rule over the shear rate and frequency region studied. Both the storage (G1) and loss (G2) modulus increase drastically as the proportion of water in the mixed solvent system increases. Similarly, both G1 and G2 are found to increase while the tan delta decreases with increasing concentration of PEOs. The addition of up to 2% w/w NaCl in an aqueous solution of 10% w/w 2 million MW PEO has no observed detrimental effect on the viscoelastic behavior.
采用动态振荡测试技术研究了聚环氧乙烷（PEO）溶液的粘弹性。利用该技术，测定了PEO分子量（MW）、浓度、由丙二醇、甲醛甘油和水组成的混合溶剂体系的组成以及NaCl盐对PEO溶液粘弹性的影响。在30℃下，在10^(-3)-2.5Hz的频率范围内检测了动态模量（G1、G2）、复数粘度大小（η大小）和损耗角正切（tanδ）。结果表明，低分子量PEO表现出类似液体的行为，而高分子量PEO由于缠结的形成表现出高弹性。在振荡测量下，复数粘度η大小表现出剪切变稀（幂律）特性。在所研究的剪切速率和频率区域内，稳态剪切粘度与复数粘度之间的关系遵循Cox-Merz规则。随着混合溶剂体系中水的比例增加，储能模量（G1）和损耗模量（G2）均急剧增加。同样，随着PEO浓度的增加，G1和G2均增加，而tanδ降低。在10%w/w 200万分子量PEO的水溶液中添加高达2%w/w的NaCl对粘弹性行为未观察到有害影响。
