In situ dielectric characterization of dynamic orientation for polymer molecular chains

Polymer orientation is a fundamental and key issue, exhibiting crucial impacts on physical properties of polymeric parts. Current methods are limited in transparent materials and fail to measure the dynamic orientation in industrial polymer processing in situ . Herein, we reported an innovative strategy that dynamic orientation for polymer molecular chains was successfully characterized in situ by dielectric method. A key dielectric-orientation theoretical model was established, and a facile interdigital electrode capacitor (IDEC) array sensor was designed. The experimental results not only agreed well with the classic elastic dumbbell model and the traditional optical measurement method, but also showed a universal applicability for different polymer solutions and a good application prospect in injection molding process. Investigated results showed that the orientation difference of 1 wt% PVDF/DMF, 1 wt% PVC/DMF and 1 wt% PS/DMF solution was 0.57, 0.97 and 0.75 at shear rate 0–407 1/s, respectively. Additionally, the method was successfully applied in injection molding (Δε, 0.25–0.88 under shear rate 56.6–250 1/s). Our strategy built a new ‘decoding fingerprint’ to the dynamic orientation of polymer.