Abstract
Pyrolitic lignin was modified through two methods. First, it was grafted with polylactide chains via asolvent-free process by ring-opening polymerization of L-lactide using calcium hydride as a catalyst. Theefficiency of grafting was determined by infra-red, nuclear magnetic resonance and time-of-flight secondaryion mass spectrometry analyses. Then, lignin particles were oxygen plasma-treated andimmersed in L-lactide solution. Infra-red and X-ray photoelectron spectroscopy revealed that chainsbearing ester groups similar to that of lactide were covalently grafted onto the lignin. Composite castfilms based on poly(L-lactide) matrix containing ungrafted lignin (lignin/PLLA), chemically-grafted lignincopolymer (PLA-g-lignin/PLLA) and plasma-treated lignin (plasma-treated lignin/PLLA) were investigated.Differential scanning calorimetry and dynamical mechanical analyses revealed that plasmatreatedlignin preserved the crystalline structure of PLLA matrix and had a significant reinforcing effectcompared with lignin and PLA-g-lignin. Results were compared with literature data.