Near Infrared Spectroscopy of Lignin Types

The natural polymer lignin is extracted from biomass, mainly wood by various technologies as described above. It accumulates in masses up to more than 50 x 10 tons at chemical pulp mills every year, worldwide, as a by-product of the pulp and paper industry [48]. When using it for material development, the most abundantly available types of lignin are modified by chemicals on extraction depending on the type of process and these might be used for their identification [53-55]. 

In order to use biomass in an environmentally friendly manner, various chemical-free approaches for lignin extraction have been applied. Pure subcriticai water and supercritical water technologies (Aquasoiv) have recently received increasing attention based on earlier research [41,44 7, 56-65]. Subcriticai water and supercritical water behave very differently 

These conditions lead to interesting extraction yields, but residence times in reactors have to be kept short in order to not degrade the biomass components substantially. In the following, lignin from lignocellulosic biomass was separated by subcritical water ( 220 °C, 5 MPa) and was characterized by various analytical methods. Its efficient utilization as a matrix for thermoplastic materials could be proved. It is important in material manufacturing to have a simple method for quality control of the raw materials. One of them can be Near Infrared Spectroscopy (NIRS), for example [53-55]. 

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