How much do you know about lignin based biodegradable materials? Lignin, together with cellulose and hemicellulose, forms the wood structure of plants. It mainly exists in the cell wall and plays a supporting and protective role. Lignin is the only natural polymer containing aromatic rings in nature. There are rich functional groups in its structure. It is the second largest biomass resource in plants, second only to cellulose, with a wide range of sources. The world produces 150 to 180 million tons of industrial lignin annually, of which less than 2% is utilized, and the majority is burned as cheap fuel or discharged arbitrarily. China produces over 20 million tons of industrial wood mills in the paper and bioethanol industries every year, but over 98% of them are directly burned, resulting in low effective utilization of resources.
About Biodegradable Polymer Materials
Biodegradable polymer materials are polymer materials that can be fully decomposed into CO2, water, and environmentally friendly substances under natural conditions, including lignin, cellulose, starch, protein, chitosan, polylactic acid (PLA), polycaprolactone (PCL), and polybutylene succinate (PBS)
Classification of Biodegradable Polymer Materials
According to the source of raw materials for fully biodegradable polymer materials, they can be divided into four types: natural biodegradable polymer materials, microbial synthesized biodegradable polymer materials, chemical synthesized biodegradable polymer materials, and mixed biodegradable polymer materials.
Total biodegradation mainly refers to the splitting or decomposition of plastic substances under the action of enzymes and microorganisms, resulting in the production of new substances or mechanical damage. The complete decomposition of lignin in nature is the result of the joint action of fungi, bacteria, and their microbial communities, involving mainly lignin catalase and enzymes. The research shows that the biodegradation process of lignin mainly includes chemical structure changes, such as side chain oxidation, demethylation/demethylation (demethylation) and aromatic ring cracking.
Advantages of lignin based biodegradable materials
Lignin is a thermoplastic polymer with the advantages of high impact strength, heat resistance, water resistance, low cost, and easy access. What other biodegradable polymer materials lack is their high cost. Using lignin as filler, it is mixed with other biodegradable polymer materials to make bioelectrolytic materials, reducing the cost of bioelectrolytic materials, and improving the properties and processing properties of composite materials such as water resistance, barrier, thermal stability, etc.
Problems in lignin based biodegradable materials
Biodegradable materials based on lignin have already laid the foundation for industrialization, but there are still the following issues that need to be addressed.
In the field of composite materials, the purity, particle size, and monodispersity of filling materials can affect the performance of composite materials. Currently, there is no exploration or understanding of lignin as a filling material.
2. The industrial formulation of lignin based biodegradable polymer materials may be limited, and product development needs to be improved, which requires a lot of application related work.
As a biodegradable material, it is necessary to control the degradation cycle and conditions, and further research is needed on the product application field, usage environment, and corresponding degradation requirements.
4. People's understanding of the structure and processing of lignin