Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 7-Day Trial for You or Your Team.

Learn More →

High-temperature extensional rheology of linear, branched, and hyper-branched polycarbonates

High-temperature extensional rheology of linear, branched, and hyper-branched polycarbonates The high-temperature extensional viscosity of three commercially available linear, branched and hyper-branched polycarbonates (PCs) were measured using a high-temperature capillary breakup extensional rheometer (CaBER) in both air and nitrogen. The experiments were performed at temperatures ranging from T = 250 to 370 °C to a maximum Hencky strain of ten. At lower end of the temperature range, no significant degradation of the linear and branched PC was observed either in the shear or extensional measurements. Beyond, T > 300 °C degradation of the three different PCs was observed. Changes to the molecular structure of the PC were observed which resulted in a dramatic increase in the extensional viscosity. The rate of growth in the extensional viscosity was found to increase with temperature, time at temperature, and, in the case of the linear and branched PC, the presence of air. For the hyper-branched case, changes to the molecular structure of the PC were found to occur more quickly under nitrogen. At these high temperatures, the increase in extensional viscosity was found to grow large enough to stop the breakup of the fluid filament all together, essentially stopping all capillary drainage. This temperature-induced cross-linking and increase in the extensional viscosity of the PC can improve the anti-dripping properties of the polycarbonate by slowing and even restricting dripping from polymeric components near high heat surges. Through these experiments, we have demonstrated measurement of the extensional viscosity to be several orders of magnitude more sensitive to temperature-induced changes to the molecular structure than measurements of shear rheology. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Rheologica Acta Springer Journals

High-temperature extensional rheology of linear, branched, and hyper-branched polycarbonates

Download PDF
16 pages

Loading next page...
 
/lp/springer-journals/high-temperature-extensional-rheology-of-linear-branched-and-hyper-lLVheFC2bT

References (50)

Publisher
Springer Journals
Copyright
Copyright © 2019 by Springer-Verlag GmbH Germany, part of Springer Nature
Subject
Materials Science; Characterization and Evaluation of Materials; Polymer Sciences; Soft and Granular Matter, Complex Fluids and Microfluidics; Mechanical Engineering; Food Science
ISSN
0035-4511
eISSN
1435-1528
DOI
10.1007/s00397-019-01157-9
Publisher site
See Article on Publisher Site

Abstract

The high-temperature extensional viscosity of three commercially available linear, branched and hyper-branched polycarbonates (PCs) were measured using a high-temperature capillary breakup extensional rheometer (CaBER) in both air and nitrogen. The experiments were performed at temperatures ranging from T = 250 to 370 °C to a maximum Hencky strain of ten. At lower end of the temperature range, no significant degradation of the linear and branched PC was observed either in the shear or extensional measurements. Beyond, T > 300 °C degradation of the three different PCs was observed. Changes to the molecular structure of the PC were observed which resulted in a dramatic increase in the extensional viscosity. The rate of growth in the extensional viscosity was found to increase with temperature, time at temperature, and, in the case of the linear and branched PC, the presence of air. For the hyper-branched case, changes to the molecular structure of the PC were found to occur more quickly under nitrogen. At these high temperatures, the increase in extensional viscosity was found to grow large enough to stop the breakup of the fluid filament all together, essentially stopping all capillary drainage. This temperature-induced cross-linking and increase in the extensional viscosity of the PC can improve the anti-dripping properties of the polycarbonate by slowing and even restricting dripping from polymeric components near high heat surges. Through these experiments, we have demonstrated measurement of the extensional viscosity to be several orders of magnitude more sensitive to temperature-induced changes to the molecular structure than measurements of shear rheology.

Journal

Rheologica Acta – Springer Journals

Published: Jun 21, 2019

There are no references for this article.