Digital imaging of the oil permeation mechanism in an oleophobic textile

Abstract

Resistance of military clothing to oil permeation is important for effective protection against chemical warfare. In this paper, while a military textile is rendered oleophobic (oil contact angle ≈ 120°) through plasma-assisted deposition of perfluorodecyl acrylate (PFAC8), permeation of the textile by silicon oil is observed. Using high-definition digital imaging, we study the oil permeation dynamics, rationalize the permeation with a plausible mechanism and identify the threshold textile pore size for prevention of the permeation. We find that oil permeates defects of PFAC8 textiles. Our data suggests a linear variation for oil permeation volume ΔV with time t and implies a gravity-driving permeation mechanism. The mechanism comprises three stages involving merging and propagation of oil–yarn contact lines. The threshold pore size d_m scales with σ/P, where σ is the oil surface tension and P is the hydrostatic head exerted by the oil drop. The paper indicates the importance of an undamaged textile structure to ‘robust’ oil resistance.