The dispersion of reinforcements in polymer matrices can be studied by linear viscoelastic behavior at low frequency, and the additional low frequency contributions in elastic modulus can be because of the relaxations of the large dispersed domains of the minor phase Elastic modulus increased with CNF content at low frequencies. For comparison, at ω = 0.07, the elastic moduli of PLA + 5 wt.% CNF with PHB carrier system and PLA + 10 wt.% CNF itself are up to 67% and 415% higher than that of neat PLA, respectively. It is also evident from Fig. 4 that PLA
composites undergo a transition from liquid-like to solid-like viscoelasticity with the increase of CNF loading in the low frequency region. In contrast, the effect of the nanofibrils on the rheological behavior is relatively weak at high frequencies, as shown in Fig. 4, suggesting that CNF has a substantial influence on large-scale polymer chain relaxations but has little effect on short-range motion of polymer chain