Extensional properties of hydroxypropyl ether guar gum solutions

Area of Science:

• Polymer Science
• Rheology
• Materials Science

Background:

• Guar gum derivatives are widely used in various industries.
• Understanding their extensional properties is crucial for applications involving fluid flow.
• Previous studies have focused on shear properties, with limited data on extensional behavior.

Purpose of the Study:

• To investigate the extensional properties of 2-hydroxypropyl ether guar gum solutions.
• To measure characteristic relaxation times and apparent extensional viscosities.
• To compare experimental results with theoretical predictions (Zimm model) and determine polymer solution behavior transitions.

Main Methods:

• Utilized a capillary breakup extensional rheometer (CaBER) to perform extensional measurements.
• Optimized CaBER geometric parameters for accurate data acquisition.
• Prepared a series of dilute to semidilute guar gum solutions at varying concentrations.

Main Results:

• Successfully measured relaxation times (1 ms range) and apparent extensional viscosities.
• Observed two distinct concentration dependencies for both shear and extensional viscosities: linear up to 0.2 wt% and power-law thereafter.
• Found good agreement between measured and predicted relaxation times at low concentrations, suggesting a transition to semidilute behavior around 3 c*.

Conclusions:

• The study provides valuable insights into the extensional rheology of modified guar gum.
• Results indicate weak interchain interactions and absence of entanglements within the explored concentration range (0.17–9 c*).
• The findings contribute to a better understanding of guar gum solution behavior in industrially relevant conditions.