影响高分子质量聚氧化乙烯溶解速度的主要因素

Study of the Dissolution of Polyethylene Oxide with a High Molecular Weight in Water

关键词:  聚氧化乙烯  溶解速度  旋转黏度计  溶解动力学

Key Words:polyethylene oxide  dissolution rate  rotary viscometer  dissolution kinetics

摘要:本研究采用旋转黏度计，研究了聚氧化乙烯（PEO）的粒度、结晶度、溶解温度、溶液浓度、溶液pH值对其在水中溶解速度的影响。结果表明，PEO在水中的分散性和水分在PEO颗粒中的扩散速度是是影响PEO溶解速度的关键因素。大颗粒的PEO堆积密度大，能够快速在水相中分散，但水分子的扩散速度慢，因此大颗粒的PEO溶解速度慢；而在小颗粒PEO上虽然水分子扩散速度快，但因PEO堆积密度小，在水中的分散性较差，因而溶解速度慢。综合而言，40～60目的PEO溶解速度最快。PEO在酸性环境中会发生部分降解，因此在酸性溶液中，PEO的溶解速度快、黏度下降；而在碱性溶液中PEO比较稳定。示差扫描量热法（DSC）表征显示PEO是一种部分结晶性聚合物，研究表明在一定的结晶度范围内，溶解速度无明显变化。在溶解动力学实验中发现，PEO在水中的溶解过程属于零级反应，主要受扩散过程影响，溶解活化能为5.2 kJ/moL，属于易溶聚合物。

Abstract:As a kind of nonionic and water dissoluble polymer, polyethylene oxide (abr. as PEO) with a high molecular weight plays an important role in papermaking. In this paper, a rotary viscometer was employed to investigate the factors which affect the dissolution rate of PEO in water. It was uncovered that the dispersion of PEO in H₂O and the diffusion of H₂O in PEO particles affect the dissolution rate of PEO obviously. However, the crystalline degree of PEO affects slightly. Although PEO particles with a big size can disperse well in water, H₂O molecules cannot permeate easily, as a consequence, it dissolves slowly. In contrast, PEO particles with a small size, H₂O can go into particles and swell PEO easily. Comparatively, PEO with a particle size of 40~60 mesh dissolves fast. PEO solution is stable in a basic environment rather than in acid environment, because H+ promotes degradation of PEO. DSC results display that PEO is a partial crystallized polymer, and the dissolution rate of PEO changes less when the crystallinity at a range of 50%~58%. Moreover, dissolution kinetics of PEO shows the dissolution of PEO is a zero-order process, suggesting the dissolution of PEO in water is crucial, and the apparent dissolution activation energy is calculated as 5.2 kJ/mol．