Table 4. Summary of the Principal Properties of the NIPU-Based Adhesives Reported in Academia.
| type of adhesive | substrates | curing conditions | speed of test (mm·min–1) | lap-shear strength (MPa) | ref |
|---|---|---|---|---|---|
| solvent-free | wood | 80 °C, 12 h + 150 °C, 30 min | 100 | 15.0 ± 1.5 | (37) |
| aluminum (Al)a | 2.0–3.0 | ||||
| solvent-free | Al | 100 °C, 18 h | 2 | 24.1 ± 1.7 | (38) |
| stainless steel (SS) | 22.1 ± 0.9 | ||||
| beech | 28 ± 1.7 | ||||
| PMMA | 17.9 ± 1.3 | ||||
| HDPE | 4.76 ± 2.5 | ||||
| dissimilar substrates | 6.7–25.0 | ||||
| hot-melt | birch wood | 130 °C, 1.18 MPa, 30 min | 10 | 0.67b | (40) |
| 3.19b | (39) | ||||
| hot-melt | pine | 220 °C, 2.75 MPa, 6 min | 2 | 3.16 ± 0.05 | (41) |
| 3.62 ± 0.02c | |||||
| 3.38 ± 0.04d | |||||
| 2.76 ± 0.09 | |||||
| 1.32 ± 0.08c | |||||
| 1.24 ± 0.04d | |||||
| beech | 230 °C, 12 mine | f | 1.02g | (42) | |
| hot-melt | Al | T not reported, 24 h | 50 | 9h | (43) |
| HDPE | <2h | ||||
| polyimide | >1.5 kg/cmi | ||||
| PHU–epoxy hybrid | Al | rt, 24 h | not reported | 12 | (48) |
| steel | 16.7 | ||||
| PHUE–epoxy hybrid | carbon steel | rt, 7 days | 5 | 10 | (49) |
| Al | 7 | ||||
| PHU–epoxy hybrid | not reported | 22 °C, 7 days | not reported | 15.8 | (50) |
| 22 °C, 7 days + 100 °C, 10 h | 22.8 | ||||
| PHU–epoxy hybrid | Al 2024-T3 | 80 °C, 48 h | ASTM D1002 | 27 | (51) |
| PHU–epoxy hybrid | Al | 30 °C, 18 h | 10 | 22 | (52) |
| + 80 °C, 1 h | |||||
| + 100 °C, 2 h | |||||
| PHU–siloxane hybrid | glass | 60 °C, 24 h | 1 | 3j | (59) |
| PHU–siloxane hybrid | SS | 100 °C, 24 h | 1 | 2.9 ± 0.6k | (60) |
| PHU–siloxane hybrid | SS | 100 °C, 24 h | 1 | 21.6 ± 0.7 | (61) |
| Al | 20.9 ± 0.9 | ||||
| oak wood | 12.8 ± 2.4 | ||||
| polyamide | 2.8 ± 0.7 | ||||
| HDPE | 0.8 ± 0.2 | ||||
| PPMA | 1.8 ± 0.2 | ||||
| composite | Al | 70 °C, 12 h | 2 | 16.3 ± 1.4 | (62) |
| Al, SS | + 100 °C, 3 h | 3.7–11.7 | (63) |
a
Cover of epoxy paint.
b
Cohesive forces investigated trough mechanical testing of the NIPU–wood joints.
c
24 h cold water.
d
2 h boiling water.
e
Three-stage hot pressing cycle (pressure 33 kg/cm2, 4 min; 15 kg/cm2, 5 min; 5 kg/cm2, 3 min).
f
Uniformly load making the specimen damaged within (60 ± 30) s according to China National Standard GB/T 17657-1999.
g
Internal bond strength.
h
No remarkable differences after thermoreversible adhesion at 100 °C of the materials.
i
Peel strength values.
j
Kept adhesive performance above the 50% after 10 days at 160 °C.
k
Kept adhesive performance after 4 days immersed in water.