Simon M A, Kusy R P
Department of Biomedical Engineering, University of North Carolina, Chapel Hill 27599, USA.
J Biomed Mater Res. 1996 Mar;30(3):313-20. doi: 10.1002/jbm.820300302.
Highly plasticized poly(vinyl chloride) (PVC) membranes (200 per hundred resin [phr]) form the basis of one class of ion-selective electrodes (ISEs). In previous work on the mechanical properties of membranes, the optimal ratio of plasticizer level employed to minimal level required for complete plasticization (phr(exp)/phrmin) was found to be 2.0. The current study was designed to determine whether this ratio is necessary or sufficient for proper ISE function. Dynamic mechanical analysis (DMA) was used to examine the effects of five plasticizers on the dynamic mechanical properties of membranes at three frequencies (110, 11.0, and 1.1 Hz) as a function of temperature (-100 degrees C to +100 degrees C); dioctyl sebacate (DOS), epoxidized propylene glycol dioleate (PGDO), ortho-nitrophenyl octyl ether (o-NPOE), epoxidized soybean oil (ESO), and epoxidized linseed oil (ELO). The glass transition temperature of PVC, which was found to be +77.1 degrees C at 11.0 Hz, was depressed by the addition of 200 phr of each plasticizer from a high of -1.4 degrees C (PGDO at 110 Hz) to a low of -70.2 degrees C (DOS at 1.1 Hz). DMA and electromotive-force (EMF) measurements on membranes plasticized with o-NPOE through a range of phr(exp)/phrmin from 0.5 to 9.3 indicated that a "transition window" occurs between phr(exp)/phrmin of 2.0 and 3.3 in which the membranes change from minimally plasticized polymer films to predictable ion-selective membranes, coinciding with the optimal mechanical properties observed previously. Based on dynamic mechanical properties and EMF response data, the optimal phr(exp)/phrmin++ ratios for membranes as a function of plasticizer were proposed: 0.8 for ESO and ELO, 1.3 for PGDO, 1.7 for DOS, and 3.0 for o-NPOE.
高增塑聚氯乙烯（PVC）膜（每百份树脂含200份增塑剂[phr]）构成了一类离子选择电极（ISE）的基础。在先前关于膜力学性能的研究中，发现所用增塑剂水平与完全塑化所需最低水平的最佳比例（phr(exp)/phrmin）为2.0。本研究旨在确定该比例对于ISE的正常功能是否必要或充分。采用动态力学分析（DMA）来研究五种增塑剂在三个频率（110、11.0和1.1 Hz）下作为温度（-100℃至+100℃）的函数对膜动态力学性能的影响；增塑剂分别为癸二酸二辛酯（DOS）、环氧丙二醇二油酸酯（PGDO）、邻硝基苯基辛基醚（o-NPOE）、环氧大豆油（ESO）和环氧亚麻籽油（ELO）。在11.０Hz下测得PVC的玻璃化转变温度为+77.1℃，添加200 phr的每种增塑剂后，玻璃化转变温度降低，从最高的-1.4℃（110 Hz下的PGDO）到最低的-70.2℃（1.1 Hz下的DOS）。对用o-NPOE增塑的膜在phr(exp)/phrmin从0.5到9.3范围内进行DMA和电动势（EMF）测量，结果表明在phr(exp)/phrmin为2.0至3.3之间出现一个“转变窗口”，在此窗口内，膜从最低程度塑化的聚合物薄膜转变为可预测的离子选择膜，这与先前观察到的最佳力学性能相吻合。基于动态力学性能和EMF响应数据，提出了膜作为增塑剂函数的最佳phr(exp)/phrmin++比例：ESO和ELO为0.8，PGDO为1.3，DOS为1.7，o-NPOE为3.0。
