Biodegradability and Compostability of Lignocellulosic Based Composite Materials

Lignocellulosic composites have attracted interest from both academia and industry due to their beneficial environmental and sustainability attributes. The lignocellulosic industry has seen remarkable improvements in the development of composites for high performance applications. Both biodegradable as well as non-biodegradable polymers are used in the design and engineering of lignocellulosic composites. Biodegradability studies of lignocellulosic composites in soil and composting environments help in planning their end-life management. Biodegradability tests are complex and dependent on the environment in which the testing is carried out. Due to this, standards have been developed by international agencies such as the American Society for Testing and Materials (ASTM) and International Organization for Standardization (ISO) to adopt and test plastic materials in both composting and soil environments. The first part of this intended review article deals with the classification of lignocellulosic composites, biodegradation and composting concepts, biodegradability testing standards, and factors affecting biodegradation. A comparative analysis of ASTM and ISO biodegradability standards in terms of testing methodology and results interpretation is provided.. A special focus is given to the biodegradation mechanisms found in polymers and their composites. The second part of this review article is devoted to biodegradation studies of lignocellulosic composites under composting conditions and soil environments. The effect of filler type, environmental conditions, and compatibilization on the biodegradation of lignocellulosic composites is discussed in detail. Also, a special section on the biodegradability of lignin-based materials is given.