Nanotechnology and its applications in lignocellulosic composites, a mini review

Nanotechnology has applications across most economic sectors and allows the development of new enabling science. The ability to see materials down to nanoscale dimensions and to control how materials are constructed at the nanoscale is providing the opportunity to develop new materials and products in previously unimagined ways. This review covers the academic and industrial aspects of the preparation, characterization, material properties, crystallization behavior; melt rheology, and processing of polymer/cellulose or cellulose/cellulose nanocomposites. Cellulosic materials have a great potential as nanomaterials because they are abundant, renewable, have a nanofibrillar structure, can be made multifunctional, and self-assemble into well-defined architectures. The fibrillation of pulp fiber to obtain nano-order-unit web-like network structure, called microfibrillated cellulose, is obtained through a mechanical treatment of pulp fibers, consisting of refining and high pressure homogenizing processes. Also, nano-whisker can be used as novel reinforcement in nanocomposites; it can be obtained by acid hydrolysis from various sources such as wood, tunicin, ramie, cotton, wheat straw, bacterial cellulose, and sugar beet. The properties of nanocomposite materials depend not only on the properties of their individual parents, but also on their morphology and interfacial characteristics. Compared with plant cellulose, bacterial cellulose has found many applications in the biomedical field as tissue engineering materials due to their good biocompatibility, mechanical properties similar to those of hard and soft tissue and easy fabrication into a variety of shapes with adjustable interconnected porosity. One of the drawbacks of cellulose whiskers with polar surfaces is poor dispersibility/compatibility with nonpolar solvents or resins. Thus, their incorporation as reinforcing materials for nanocomposites has so far been largely limited to aqueous or polar systems. To overcome this problem and broaden the type of possible polymer matrices, efforts of surface modification have been made. These attempts include surfactant coating or graft copolymerization.