期刊
ACS APPLIED MATERIALS & INTERFACES
卷 8, 期 2, 页码 1458-1467出版社
AMER CHEMICAL SOC
DOI: 10.1021/acsami.5b10723
关键词
cellulose nanocrystal; nanoparticle modification; isocyanate chemistry; thermal stability; polyurethane; polymer nanocomposite; dispersion; mechanical properties
资金
- USDA Forest Products Laboratory (FPL)
The unequal reactivity of the two isocyanate groups in an isophorone diisocyante (IPDI) monomer was exploited to yield modified cellulose nanocrystals (CNCs) with both urethane and isocyanate functionality. The chemical functionality of the modified CNCs was verified with ATR-FTIR analysis and elemental analysis. The selectivity for the secondary isocyanate group using dibutyl tin dilaurate (DBTDL) as the reaction catalyst was confirmed with C-13 NMR. The modified CNCs showed improvements in the onset of thermal degradation by 35 degrees C compared to the unmodified CNCs. Polyurethane composites based on IPDI and a trifunctional polyether alcohol were synthesized using unmodified (um-CNC) and modified CNCs (m-CNC). The degree of nanoparticle dispersion was qualitatively assessed with polarized optical microscopy. It was found that the modification step facilitated superior nanoparticle dispersion compared to the um-CNCs, which resulted in increases in the tensile strength and work of fracture of over 200% compared to the neat matrix without degradation of elongation at break.
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