Structural, thermal and mechanical properties of composites of poly(butylene adipate-co-terephthalate) with wheat straw microcrystalline cellulose

Structural, thermal and mechanical properties of the compostable composites comprising a biodegradable aliphatic–aromatic copolyester (namely, the poly(butylene adipate-co-terephthalate; PBAT), and microcrystalline cellulose (MCC) derived from agricultural waste, the wheat stalk, were investigated. Purely physical interaction between the components was found to be responsible to get the MCC phase quite uniformly embedded in the PBAT matrix, the latter being the dominating component of the composites surface. There were two distinct thermally activated degradation regimes characterized by separate activation processes corresponding to the decomposition of the MCC and the PBAT phases, respectively. The physically bound and rather weak but large PBAT–MCC interfacial areas provoked more rapid thermal degradation of the composites compared to the pure components. While the PBAT acted as a highly ductile material upon tensile loading, the composites maintained high ductility only up to 20% by weight of the MCC. The drastic reduction in the ductility for higher filler loading was attributed to the possible void formation at the interfacial region followed by crack initiation and propagation leading eventually to the premature specimen fracture. The composite materials thus fabricated were hence found to suit for low-load bearing applications.