Temperature effects on dynamic water absorption into paper

Area of Science:

• Materials Science
• Physical Chemistry
• Fluid Dynamics

Background:

• Understanding water absorption in porous materials like paper is crucial for various industrial applications.
• Existing models, such as the Lucas-Washburn equation, often fail to capture complex dynamics under varying conditions.

Purpose of the Study:

• To investigate the mechanisms governing short-time water absorption into paper.
• To analyze the influence of temperature on the water absorption rate in paper.

Main Methods:

• Analysis of previously published data on water absorption into paper.
• Investigating liquid uptake dynamics using a dynamic contact angle model.
• Examining molecular processes at the air-liquid interface and their effect on wetting velocity.

Main Results:

• A dynamic contact angle effect, attributed to contact line friction, successfully explains short-time liquid uptake.
• The rate of water absorption increases with temperature due to molecular adsorption and reduced interfacial tension.
• The classical Lucas-Washburn equation proved insufficient for predicting water absorption at short times and across different temperatures.

Conclusions:

• Short-time water absorption in paper is governed by dynamic contact angle effects.
• Temperature-dependent water absorption is driven by enhanced molecular adsorption and altered interfacial tension.
• The Lucas-Washburn equation requires significant modification or replacement for accurate modeling of paper's water absorption behavior.