Green Approaches, Potentials, and Applications of Zinc Oxide Nanoparticles in Surface Coatings and Films

Table 4

List of mechanical data for coatings/films embedded with ZnO NPs.

Coating/film materials	Substrate	Mechanical data		Water activity		Ref.
		Coating/film materials only	Coating/film materials with ZnO NPs	Coating/film materials only	Coating/film materials with ZnO NPs
Jatropha oil-based epoxy acrylate (AEJO)	Steel	Adhesion: 45.7 psi; Pencil hardness: HB; Scratch hardness: 1.0°N	Adhesion: 133.0 psi; Pencil hardness: 6 H; Scratch hardness: 2.4 N	WCA: 85.1°	WCA: 99.35°	[8]
Hydroxypropyl cellulose (HPC)	Paper	TS in machine direction: 42.75 N; TS in cross direction: 17.76 N	TS in machine direction: 44.48°N; TS in cross direction: 19.20 N	—		[9]
Monoethanolamine (MEA)	Cotton fabric	ZnO-coated surface test details; UV illumination: 700 minute; Outdoor exposure time: 40 days; Scratch resistance test: 1500-mesh sandpaper with 1 kg load at 1 cm/s speed for 20 cycles.; Conclusion, ZnO coating still gives hydrophobicity property to surface after all these tests.		WCA: 0° (No coating)	WCA: 154°	[35]
Gelatin	Film	ETB: 18.98%; UTS: 6.015 MPa; YM: 142.85 MPa	ETB: 12.70%; UTS: 18.29 MPa; YM: 853.76 MPa	Moisture absorption percentage of bare gelatin is reduced with the addition of ZnO nps to 5.57%		[38]
Starch (st)	Film	ETB: 98.00%; TS: 3.67 MPa YM: 7.80 MPa	ETB: 55.67%; TS: 7.5 MPa YM: 25.44 MPa	%solubility: 32.25%; WVP (10^−7 g/mhPa): 11.46	%solubility: 24.07%; WVP (10^−7 g/mhPa): 8.32	[19]
Chitosan	Film	—		% solubility in water: 78.3%	% solubility in water: 43.2%	[42]

Tensile strength (TS), elongation to break (ETB), ultimate tensile strength (UTS), Young’s modulus (YM), water contact angle (WCA), water vapour permeability (WVP), and percentage of solubility in water (% solubility).