SEC analysis of the molar mass of lignin isolated from poplar(Populus deltoides x maximowiczii) and Scots pine (Pinus sylvestris L.) wood

SEC analysis of the molar mass of lignin isolated from poplar (Populus deltoides x maximowiczii) andScots pine (Pinus sylvestris L.) wood. The aim of the study was to analyse the molar mass of lignin, which can bea waste product in bioethanol production technology. A studies of isolated lignin from two species: Populusdeltoides x maximowiczii (hardwood) and Pinus sylvestris L. (softwood) were conducted to determine its molarmass using the SEC technique. Two acidic methods of lignin isolation were used during the studies. The use of72% sulphuric acid yielded higher values of Mn, Mw and PDI and the lignin was better dissolved in 0.5%LiCl/DMAc system, which determined the continued use of this method in further studies. The Klason ligninsamples for both species were subjected to milling at three time configurations: 5, 15 and 30 min, which resultedin an increase in the aforementioned values. The tests carried out and the analysis of the results indicated thatmilling times longer than 5 min caused degradation and repolymerisation of the lignin, as confirmed by themolar mass distributions. Some of the wood samples were pretreated with steam explosion and next isolatedKlason lignin were milled. SEC analysis showed a decrease in Mn values with increasing milling time, while anincrease in Mw and PDI for steam exploded poplar lignin. For analogical obtained steam exploded pine lignin,the values increased directly proportional. For the milling carried out, 5 min was recommended, so that ligninsolubility increased and molar mass was determined more reliable.