Understanding and Prediction of Liquids Retention on Commonly Used Plastics with Symmetrically Arranged Structure

Abstract

Wetting behaviors commonly happen in the daily life and it is essential and beneficial to control solids’ wettability in the industrial process. Polymers in forms of plastics have the most extensive applications in all kinds of products. This research aims to empirically study wettability of commonly used plastics with symmetrically arranged surface structure, and then proposes a methodology for solids’ wettability predictions.

The research starts from studying various liquids’ contact angles on plastic surfaces. It was found that surface structures within certain dimensions, in terms of liquid-solid contact length parameters, have linear relationship with liquids’ contact angles. Results were found explanations by further studied the change of plastics’ surface free energy due to their surface structures. Such results were used to develop empirical models for liquids’ contact angles and solids’ surface free energy estimations, and models were verified by liquid-solid interfacial tensions.

The extending research was investigated based on aforementioned results. Liquids’ contact angle hysteresis and retentions on inclined surfaces were studied. Liquids’ advancing and receding contact angles were found to maintain the same ratio on structured plastic surfaces with various dimensions and inclined angles. The new finding confirms and further extends the statement proposed in the literature. Based on liquid-solid interfacial tension and gravity effect, an empirical formula was proposed to estimate liquids’ critical retention volumes on inclined plastic surfaces. Integrating the formula with predicted advancing contact angles, the prediction of liquids’ critical retention volumes on structured plastic surfaces becomes possible.