The Lignoboost process [5], which allows the isolation of a lignin fraction from the Kraft process, is one such method but there are many other biomass fractionation technologies such as organosolv, steam explosion, acid hydrolysis, hot water extraction, and ammonia fiber expansion [6]. The different processes will yield different types of lignin, but also the same process with different process parameters [7] could affect the structure and properties of the lignin, therefore it is of great importance to properly characterize technical lignins produced by novel fractionation technologies to optimize their use in different applications, as seen from studies that compared how the chemical structure affects the product, i.e., in carbon fiber [8] and phenol-formaldehyde resin [9]. When studying lignin as a source of fuel or chemicals, the focus has often been to catalytically cleave the alkyl-aryl ether bonds [10; 11], and thus for such an end use, it would be preferable to have an intact lignin with large amounts of \(\beta\)-O-4 linkages and low degree of condensation. There are also applications when lignin is used in its polymeric form, i.e., used as a copolymer, or in polymer blends, or in composites [12; 13; 14; 15] and in these cases condensation does not necessarily affect the properties negatively. To improve the functional properties of polymer blends, and to increase the compatibility of lignin with other polymers, chemical modification or derivatization is often necessary [16; 17; 18; 19]. The compatibility [20] and the thermal stability [21] can be tailored by altering the derivatization agent e.g., in lignin esters by increasing the length of the esters. The innate properties of polymers can also be improved in blends with lignin as seen when poly lactic acid (PLA) was blended with fatty acid esterified lignin [22]. These blends are often thermally treated or processed, e.g., with temperatures around 170 \({}^{\circ}\)C for PLA [23; 24] and temperatures up to 220 \({}^{\circ}\)C for poly(ethylene oxide) blends [25]. The blending temperature can be crucial as it has been shown that lignin enhance the degradation polymers such as PLA at elevated temperatures [26]. In this article we have studied the softwood lignin fraction obtained from a novel pressurized hot water extraction (PHWE) biorefinery process [27; 28]. In the first step of the process the hemicelluloses are isolated by extraction from wood chips with hot water (max 150 \({}^{\circ}\)C) at oxygen-starved conditions [27]. After the separation of the hemicelluloses the chips are cooked with alkali in a second step to isolate the cellulose fraction as described by [PERSON] et al. [28]. The lignin, called BLN lignin, can then be precipitated and purified from the black liquor. The process is currently being up-scaled for commercial applications. In our earlier work we have analyzed the structural changes that the process caused to birch lignin and showed that the process clearly affects the structure [29]. As the process caused condensation and increased the amount of free hydroxyl groups, this lignin may be more suitable for applications where it is used in its polymeric form. The main objective of this study was to investigate the structural and thermal properties of the BLN lignins from the softwoods Norway spruce and Scots pine. The lignins were also chemically modified by acetylation and methylation of the phenolic hydroxyl groups. These modifications were performed as it has  
Figure 1: The lignin monomeric building blocks (**a**) \(p\)-couamaryl alcohol (H); (**b**) coniferyl alcohol (G); and (**c**) sinapyl alcohol (S). been shown that especially free hydroxyl groups are labile to thermal treatments [30]. These types of reactions, or similar types of reactions, are also often used to increase the compatibility with other polymers. The lignin was also fractionated by solvent fractionation, which illustrates that the lignin can be further tailored into more narrow molar mass fractions by simple separation methods.