Cas 518 47 8

Solutions with 4 different compositions of HPC (Klucel Pharm HPC, grade LF, Ashland Inc, Covington, Kentucky, USA) with a mean molecular weight of 95 000 Daltons 51 and EC (Ethocel Standard Premium, viscosity 10 cps, Dow Cellulosics, Dow Chemical Company, Midland, Michigan, USA) with a mean molecular weight of 30 000 Daltons 52 were prepared. For the microscopic analysis, 6 wt% of polymer blend was mixed in a solution of 2 mM Na-fluorescein (CAS. 518-47-8, Sigma Aldrich, St. Louis, Missouri, USA) in ethanol (CAS. 64-17-5 AnalR NOR-MAPUR s 96%, VWR Chemical, Radnor, Pennsylvania, USA). The EC/HPC polymer ratios studied were 22, 30, 45 and 60 wt% of HPC in the polymer blend. The compositions were chosen according to previous studies performed on the same system. 45, 47 Fluorescein was chosen as a fluorescent tracer because it exhibits a strong affinity to HPC. 43 For the viscosity measurements, 16 solutions were prepared with the following compositions: 22, 30, 45, and 60 wt% HPC and 4 ratios of solvent: 94, 90, 85 and 80 wt% of ethanol (96%). Ethanol was added to the polymer blend and the solutions were stirred overnight.