ARTICLE IN PRESS
JID: JOBAB
[m3GeSsc;February 6, 2026;11:5]
Z. Wei, J. Liu, Y. Wang et al.
Journal of Bioresources and Bioproducts xxx (xxxx) xxx
Fig. 4. Structure and mechanical properties of PLS emulsion coated paper (P-PLS). The SEM images of (a) uncoated paper, (b) PLS 0 emulsion coated paper (P-PLS 0 ), and (c) PLS 2 emulsion coated paper (P-PLS 2 ). (d) Schematic diagram illustrating structure of P-PLS 0 , and PLS 0.25, 0.5, 1, 1.5, 2 emulsion coated paper (P-PLS 0.25, 0.5, 1, 1.5, 2 ). (e) Tensile strength of uncoated paper, and P-PLS. (f) Wet tensile strength of uncoated paper, and P-PLS. (g) Photographs showing that a 2 cm-wide P-PLS 2 can easily lift a 4 kg kettlebell after being soaked in water for 20 min.
incorporation of SA into the coating, the WCA of the coated paper gradually increased, demonstrating hydrophobic properties, with all WCAs exceeding 90°, and the maximum WCA of P-PLS 2 reaching (111.2 ± 4.5)° ( Fig. 5 a). The improvement in WCA can be attributed to the incorporation of hydrophobic SA particles into the hydrophilic PVA matrix within the PLS emulsion coating. Therefore, the partially exposed SA particles on the surface provide the coating with enhanced hydrophobic properties. Due to the large number of SA particles adhering to its surface, P-PLS 2 − M also showed a high WCA ( Fig. 5 a). Furthermore, compared to the rapid absorption of water droplets on uncoated paper, the absorption rate on PLS emulsion-coated paper was slower due to the dense coating structure and the hydrophobicity of SA. Specifically, P-PLS 1.5 and P-PLS 2 , which contain higher SA content, showed only a slight decrease in WCA over 180 s, exhibiting resistance to water absorption (Fig. S12). The water-proof performance of the coated paper was further confirmed by the Cobb 60 test, which represents the amount of water absorbed per unit area of paper within 60 s. Due to the poor water-proof performance of uncoated paper, its Cobb 60 value reached as high as (89.59 ± 5.63) g/m 2 . Due to the dense structure of the coating and the hydrophobic properties of the SA particles, the Cobb 60 value of the coated paper was significantly reduced. As the SA content increased, the Cobb 60 value gradually decreased, reaching a minimum of (17.73 ± 0.09) g/m 2 (P-PLS 2 ), representing an 80.2% reduction compared to the uncoated paper ( Fig. 5 b). This further demonstrates the good water-proof properties imparted to
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