Real time optical and mechano-optical studies during drying and uniaxial stretching of Polyetherimide films from solution

• Published in: Polymer (Guilford) 2015-06, Vol.68, p.168-175
• Main Authors: Jiang, Fanhui, Cakmak, Miko
• Format: Article
• Language: English
• Subjects: Birefringence; Drying; Evolution; Monitoring; Polyetherimide; Polyetherimides; Real time; Real-time characterization; Solvent-cast film; Stretching; True stress
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2015.05.011

In order to have a fundamental understanding of the temporal evolution of physical characteristics of Polyetherimide (PEI) film and processing parameters, real time measurements are essential. Because drying and stretching processes of solvent-cast polymer film are complex, off line measurements are unable to reveal the temporally varying detailed information, especially for fast “transient events”. To solve the problem, two measurement systems, one for drying that tracks real time thickness, weight, surface temperature, in-plane and out-of-plane birefringence of solution casting film, and another for uniaxial stretching that tracks real time true stress, true strain and birefringence of stretched film are used. By using these systems, we are able to systematic investigate the development of optical anisotropy through in and out of plane birefringence monitoring drying of solution cast films and their mechano-optical behavior during stretching, and quantify the influence of solvent N-methyl-2-pyrrolidinone (NMP) on these relationships. [Display omitted] •Drying of polyether imide was investigated using instrumented real time measurement system.•During drying isotropic to anisotropic optical transition was observed. Initially randomly oriented polymer chains become oriented in the film plane exhibiting uniaxial optical symmetry.•Effects of remnant solvent concentration on the mechano optical behavior of the films were quantified and mapped.