To improve the compatibility and processability of alkali lignin, polycaprolactone was grafted on the the backbones of lignin by ring-opening polymerization of ε-caprolactone under anhydrous conditions using n-butyl titanate as catalyst. The effects of ratio of monomer to catalyst, reaction temperature and time on the grafting rate were investigated. The prepared copolymers were characterized by thermogravimetric analysis, DSC analysis, 1H NMR and P spectrum. The results showed that when the molar ratio of ε-caprolactone to lignin was 10 mol/mol, the reaction time was 24 h, the reaction temperature was 130°C, the amount of catalyst was 2% (based on the amount of caprolactone), the grafting rate of lignin can reach up to 135.64%. Due to the modification, lignin-g-polycaprolactone copolymer exhibted higher crystallinity and therefore the thermal stability of copolymer was increased. NMR proton analysis showed ε-caprolactone was grafted onto lignin, while a self-polymerization reaction took place to generate polycaprolactone. 31P NMR results indicated that polycaprolactone was connected to the phenolic hydroxyl group and alcohol hydroxyl group of the alkali lignin, and the former was more active.<br/>

Grafting polycaprolactone onto alkali lignin for improved compatibility and processability

2019 Spring National Meeting

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