English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

This paper deals with the contributions of stress and molecular orientation to the birefringence induced in an injection molded polymer strip. It is well known that the birefringence observed in polymeric materials is dominated both by the stress and by the molecular orientation produced in the polymer. This means that, in order to apply the measured birefringence for evaluation of the degree of molecular orientation, which results in anisotropic mechanical, optical and/or thermal properties of the molded strip, the stress-based birefringence and molecular orientation based birefringence must be separated from the total birefringence. In this paper, therefore, the generation of birefringence due to stress and molecular orientation was discussed on the basis of the master curve of the birefringence-strain coefficient.Using the master curve in conjunction with the Boltzmann's superposition principle and time-temperature reducibility, the process of birefringence generation within an injection-molded polymer strip was numerically estimated. The results showed that the birefringence induced by the thermal strain is mainly due to molecular orientation in the core region, while the birefringence in the surface region is also dominated by the thermal stress. On the other hand, it was also shown that polymer melt flow during the filling stage of the injection-molding process results in the birefringence purely due to molecular orientation, and that the birefringence tends to be frozen in the surface region.

Estimation of Birefringence Due to Stress and Molecular Orientation Induced in an Injection-molded Polymer Strip