Sensitive spinline-type extensional viscometer for mobile liquids employing very small liquid volumes

A method for determining extensional viscosity of a solution, comprising the steps of:

• (a) calculating tensile stress within the solution;
• (b) calculating the solution's stretch rate;
• and
• (c) calculating extensional viscosity of the solution as a ratio of tensile stress to stretch rate.

An extensional viscometer for measuring tensile stress within a liquid, comprising:

• a liquid reservoir without a pressure measuring device;
• a first capillary through which liquid drains, connected to said liquid reservoir;
• and
• a second capillary positioned beneath said first capillary thereby creating a gap between said first and second capillaries, such that the liquid is stretched as it passes from said first capillary to said second capillary.

A method for determining extensional viscosity of a liquid, comprising the step of:

• (a) inferring fluid stress by measuring change in flow rate of the liquid during passage through a vertical capillary, wherein the change in flow rate is calculated by:
• determining the liquid's gravity-driven flow rate;
• determining the liquid's stretched flow rate;
• and
• subtracting the stretched flow rate from the gravity-driven flow rate.