Evaluation and potential application of novel cellulose nanofibril and lignin-based-graphite functionalized flexible polyurethane foam

Recently, cellulose nanofibrils (CNFs) and lignin-based graphite have been explored due to their biodegradability and biocompatibility. In this study, CNFs and lignin-based graphite were used to partially replace petroleum-based polyols and fabricate novel flexible polyurethane foam (Flex-PUF) composite. The impacts of CNFs and graphite on the physical, thermal, and structural properties of Flex-PUF were systematically evaluated. Compared to graphite, the addition of CNFs had less influence on the thermal stability of Flex-PUF. The differential scanning calorimetry results revealed that replacing polyols with CNFs did not significantly change the decomposition temperature of the urea bond. However, adding 40% of graphite increased the decomposition temperature to 310 degrees C, while further adding graphite to 50% decreased the decomposition temperature to 240 degrees C. Nitrogen adsorption isotherm confirmed that the specific surface area of the foam first decreased to 99 m(2)/g and then increased to 175 m(2)/g with the increase of CNFs from 10 to 30%. However, there was an opposite trend with the respect of graphite. The specific surface area of the foam first increased to 262 m(2)/g and then abruptly decreased to 107 m(2)/g with the increase of graphite content. Water contact angle test revealed good hydrophobicity for all foam samples. Finally, promising crude oil/water separation performance was demonstrated by Flex-PUF sample functionalized with both CNFs and graphite, with fresh water passing through the foam sample, while the crude oil being held steady in the foam. Graphic abstract