Biopolymer nanocomposites of polyhydroxybutyrate and cellulose nanofibrils: Effects of cellulose nanofibril loading levels

In this paper, the effect of cellulose nanofibrils (CNFs) loading levels on the conventional and dynamic mechanical, morphological, thermal and rheological properties of the polyhydroxybutyrate (PHB) biopolymers were studied. According to the results, adding CNFs from 1% to 20% generally didn't provide any improvement in the flexural, tensile and izod impact strength attributable to void formation and pulling out and agglomeration of nanofibrils in the matrix, which was observed during morphological characterization, however adding CNFs substantially increased both flexural and tensile modulus of elasticity. Thermal analysis showed that adding CNFs generally decreased degradation at high temperatures of the biopolymer nanocomposites (BNCs) The addition of CNFs at 1, 10 and 20% increased the E' and E'' of neat PHB but the other loadings decreased them, and tan delta increased with CNF loadings of 3, 5, 10 and 20%, and finally adding CNFs didn't change the rheological behavior of the composites.