Crystallization and creep of the graphite nanosheets based poly(butylene adipate-co-terephthalate) biocomposites

• Graphite nanosheets have good distribution throughout the PBAT matrix.
• The presence of graphite has large influence on the crystallization of PBAT.
• Nucleation dominates overall crystallization kinetics at experimental conditions.
• The creep strain of system is highly restrained by the presence of graphite.
• The reduced creep level is due to suppressed relaxation of chain coins.

Biodegradable poly(butylene adipate-co-terephthalate) (PBAT) composites containing graphite nanosheets were prepared by melt compounding. The results reveal that the nanosheets have full distribution throughout the PBAT matrix, although they are still dispersed as the multilayered stack. Those well distributed graphite nanosheets act as the heterogeneous nucleating agent to facilitate formation of crystal nucleus and also as the physical hindrance to retard crystal growth. But the nucleation dominates overall crystallization kinetics at experimental graphite loading levels because the composites show higher crystallization rates and lower activation energies than those of the neat PBAT. The results from creep study further confirm the role of physical hindrance played by graphite nanosheets because the creep strain of system is highly restrained by the presence of nanosheets. However, this inhibiting effect is attributed to suppressed relaxation of chain coins, rather than confinement to chain segments.