Design and Effect of a Resin Infiltration Method to Enhance the Interlayer Adhesion of Additively Manufactured PEEK Parts

. 2025 Oct 23;17(21):2819. doi: 10.3390/polym17212819

Reference volume of dense PEEK specimen (infill percentage 100%), with: $ρ_{P E E K} = 1.31 g / {c m}^{3}$	$V_{P E E K, 100 %} = \frac{m_{P E E K, 100 %}}{ρ_{P E E K}}$ (1)
Volume of PEEK at different infill percentages (x%) with: x% = 70%, 50%, 30%	$V_{P E E K, x %} = \frac{m_{P E E K, x %}}{ρ_{P E E K}}$ (2)
Mass of epoxy resin after infiltration	$m_{r e s i n, x %} = m_{i n f i l t r a t e d, x %} - m_{P E E K, x %}$ (3)
Volume of epoxy resin after infiltration, with: $ρ_{r e s i n} = 1.11 g / {c m}^{3}$	$V_{r e s i n, x %} = \frac{m_{r e s i n, x %}}{ρ_{r e s i n}}$ (4)
Void fraction after printing with specimens at x% infill	${∆ V}_{v o i d}^{p r i n t} (x %) = (1 - \frac{V_{P E E K, x %}}{V_{P E E K, 100 %}}) \times 100$ (5)
Void fraction after infiltration with specimens at x% infill	${∆ V}_{v o i d}^{i n f i l t r a t e d} (x %) = (1 - \frac{V_{P E E K, x %} + V_{r e s i n, x %}}{V_{P E E K, 100 %}}) \times 100$ (6)