To improve the Heat Deflection Temperature of polylactide (PLA), nanocomposites were prepared with
modified cellulose nanocrystals (CNCs) by melt blending. The preparation of acetate and lactate modified
CNCs (AA- and LA-CNCs) was performed by a green one-pot dual acid (organic acid and HCl) method
such that acid hydrolysis and Fischer Esterification occur in tandem. The degree of substitution for AACNCs
and LA-CNCs, determined by FTIR, are 0.12 and 0.13, respectively. Relative to unmodified CNCs,
esterification of CNC surfaces with lactate and acetate moieties resulted in a 40 C increase in thermal
stability. At 5 wt% loading of CNCs, LA-CNCs gave superior reinforcement below and above the glass
temperature of PLA, corresponding to a 31% and 450% increase in PLA's storage modulus compared to
neat PLA. An increase in PLA's heat deflection temperature by 10 C and 20 C was achieved by meltblending
PLA with 5 and 20% LA-CNCs, respectively. The above studies provide indirect evidence that
LA-CNCs were best dispersed (lowest tendency to aggregate) in the PLA matrix. This hypothesis was
confirmed through direct visualization using AFM. Thus, a simple modification strategy for CNCs was
devised that enables the formation of PLA nanocomposites with high extents of nanofiber dispersion
within the matrix. Furthermore, the dispersion of CNCs in PLA matrices is profoundly influenced by
relatively small changes in the modification chemistry, in this case, appending lactate vs. acetate groups
To improve the Heat Deflection Temperature of polylactide (PLA), nanocomposites were prepared withmodified cellulose nanocrystals (CNCs) by melt blending. The preparation of acetate and lactate modifiedCNCs (AA- and LA-CNCs) was performed by a green one-pot dual acid (organic acid and HCl) methodsuch that acid hydrolysis and Fischer Esterification occur in tandem. The degree of substitution for AACNCsand LA-CNCs, determined by FTIR, are 0.12 and 0.13, respectively. Relative to unmodified CNCs,esterification of CNC surfaces with lactate and acetate moieties resulted in a 40 C increase in thermalstability. At 5 wt% loading of CNCs, LA-CNCs gave superior reinforcement below and above the glasstemperature of PLA, corresponding to a 31% and 450% increase in PLA's storage modulus compared toneat PLA. An increase in PLA's heat deflection temperature by 10 C and 20 C was achieved by meltblendingPLA with 5 and 20% LA-CNCs, respectively. The above studies provide indirect evidence thatLA-CNCs were best dispersed (lowest tendency to aggregate) in the PLA matrix. This hypothesis wasconfirmed through direct visualization using AFM. Thus, a simple modification strategy for CNCs wasdevised that enables the formation of PLA nanocomposites with high extents of nanofiber dispersionwithin the matrix. Furthermore, the dispersion of CNCs in PLA matrices is profoundly influenced byrelatively small changes in the modification chemistry, in this case, appending lactate vs. acetate groups
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