Biodegradable poly(vinyl alcohol) foams supported by cellulose nanofibrils: processing, structure, and properties.

In order to capture savings in energy and ambitious environmental targets, biodegradable composite foams of poly(vinyl alcohol) (PVA) supported by cellulose nanofibrils (CNF) were prepared through unidirectional freeze-drying technology. Effects of the content of CNF, the solid content of the precursor suspension, and the quenching temperature on the microstructure and properties of the composite foams were investigated by scanning electron microscopy (SEM), compressive testing, X-ray diffraction (XRD) analysis, water uptake, and biodegradation tests. Results show that the incorporation of CNF preferably at a weight ratio of 30 wt % greatly enhanced the mechanical strength and modulus, energy absorption, water resistance, and dimensional stability of the composite foams because of the rigid and semicrystalline nature of CNF as well as regular and compact pore structures. Furthermore, the biodegradation tests performed in a simulated aerobic compost environment suggested that the involvement of CNF significantly accelerated the pace of biodegradation of the composite foams. Hence, we provided some meaningful information on the biomimetic cellular composite foams with controllable morphs and properties by varying the freeze-drying process and composition.