Table 1. Summary of Microscale Celluloses and Nanocelluloses in PU Synthesis with 2:1 MDI/PTMEG and Chain Extension with 1,4-BD,29−32,34 Except for the One with 20 mol% Excess MDI and No Chain Extender (CE)33,a.
| micro/nanocellulose | cell (wt %) | cell OH content (mmol/g) | preparation | media | dispersing method | prepolymer precursor | modulus (MPa) | strength (MPa) | strain (%) | optimal cell content (wt %) | MDI (wt %) of PU |
|---|---|---|---|---|---|---|---|---|---|---|---|
| MCC29 | 1–10 | NA | none | DMF (0.3 wt % LiCl) | none | PTMEG (1000) | 4.9–21.1 | 8.0–24.0 | 390–970 | 5 | 31.5 |
| 4.3× | 3× | 2.5× | |||||||||
| MFC30 | 0.5–5 | 1.25 | none | DMF | none | PTMEG (1000) | 1.2–27.7 | 5.8–26.3 | 761–1387 | 1 | 31.5 |
| 23× | 4.5× | 1.8× | |||||||||
| CNC31 | 0.5 (0–3 mol% excess MDI) | NA | none | PTMEG (1000) | homogenization (rotor–stator homogenizer) | PTMEG (1000) | 16.6–16.1 | 41.7–58.3 | 1096–1011 | 0.5 | 35.8 |
| 1× | 1.4× | 0.9× | |||||||||
| CNC32 | 0.5–5 | 2.8 | freeze-drying | DMF | sonication* | PTMEG (1000) | 8.2–44.9 | 7.5–61.5 | 751–994 | 1 | 31.5 |
| 5.5× | 8.2× | 1.3× | |||||||||
| CNC33 | 0.5–2 | NA | solvent exchange to acetone | hydroxylated soybean oil (Agrol 3.6) | sonication (IKA T 18 Basic Ultra-Turrax) | hydroxylated soybean oil (Agrol 3.6) | 11.3–45 | 2.5–5.3 | N/A | 1 | 35.0 |
| 4× | 2.1× | ||||||||||
| TEMPO- CNF34 | 0.5–2 | NA | solvent exchange to acetone | DMF | sonication (VCX 500 Ultrasonic Processors, 300 W,1 min) | PTMEG (2000) | 8.7–4.9 | 4.5–39.8 | 419–2344 | 1 | 19.5 |
| 0.6× | 8.8× | 5.6× |
a
Tensile property improvement was indicated by times of increases (×). * Condition not specified.