## 4 Conclusions  
In this study we have determined the structural characteristics and thermal properties of softwood lignins obtained from a novel PHWE process and their acetylated and methylated derivatives. It was found that the lignin from the process, which is optimized for obtaining the carbohydrate fraction from wood, clearly altered the lignin structure when compared to MWL from the same wood chips. The sulphur-free lignin shared many common traits shared among technical lignin [42] such as the reduction of the aliphatic chains and natively occurring lignin linkages. Condensed structures that had formed during the process were detected, mainly at the C\({}_{5}\)-H position of the aromatic ring. The polymeric lignin had larger amounts of carboxylic groups and free phenolic groups comparedto MWL. The lignin from the two different softwood species showed very little differences, both structurally and in thermal properties, and can as such be used as mixtures for potential applications. The thermal properties of the softwood lignins were compared to hardwood birch lignin from the same process and the properties were similar, for both unmodified and modified lignin. It was also shown that the BLN lignin could easily be separated by solvent fractionation to prepare narrower molar mass portions with slightly different functional group compositions. The lignins had high T\({}_{\text{dst\,95\%}}\) values (273-302 \({}^{\circ}\)C) and the free phenolic groups could easily be chemically modified to tailor the chemical properties, which make this lignin and its derivatives promising candidates for the use in polymer blends.  
The following are available online. Figure S1: HSQC of acetylated birch lignin, Figure S2: HSQC of acetylated pine lignin, Figure S3: HSQC of acetylated spruce lignin, Figure S4: HSQC of partially methylated birch lignin, Figure S5: HSQC of partially methylated pine lignin, Figure S6: HSQC of partially methylated spruce lignin, Figure S7: HSQC of fully methylated pine lignin, Figure S8: \({}^{31}\)P-NMR of the BLN softwood lignin and MWL, Figure S9: \({}^{31}\)P-NMR of the partially methylated BLN lignin, Figure S10: \({}^{31}\)P-NMR of the fully methylated BLN pine lignin, Figure S11: \({}^{31}\)P-NMR of the acetylated BLN lignin, Figure S12: \({}^{31}\)P-NMR of the softwood lignin fractions besides the BLN lignin (MTBE insoluble), Figure S13: \({}^{13}\)C-NMR of pine BLN and MWL, Figure S14: \({}^{13}\)C-NMR of spruce BLN and MWL, Figure S15: \({}^{13}\)C-NMR of acetylated spruce and pine BLN lignin, Figure S16: TGA of unmodified pine lignin and acetylated pine lignin.  
Conceptualization, L.L., A.P., S.v.S., L.V., S.W. and P.E.; methodology, L.L., A.P., S.W. and P.E.; validation, L.L.; torsional analysis, L.L., A.P. and I.S.; resources, L.L., A.P., S.v.S., L.V.; data curation, L.L.; writing--original draft preparation, L.L.; writing--review and editing, L.L., A.P., S.W. and P.E.; visualization, L.L.; supervision, S.W. and P.E.; project administration, S.W. and P.E.; funding acquisition, L.L., S.W. and P.E.  
This work was funded by Suomen Luonnonvarain Tuktimussaatio and by Fortum Saatio project 201700061. This work is also part of the activities at the Johan Gadolin Process Chemistry Centre, a Centre of Excellence appointed by Abo Akademi University.  
[PERSON] is acknowledged for supplying the MWL and Institute of Wood Technology and Renewable materials at BOKU is acknowledged for access to the TGA equipment.  
The authors declare no conflict of interest.