Study of lignin dispersion in low-density polyethylene

A maximum of 20% (w/w) lignin was used as a filler in low-density polyethylene (LDPE), together with 3–6% maleic anhydride-grafted LDPE as compatibilizer and 3–10% copper(II) sulphate pentahydrate (CuSO 4 ·5H 2 O) as lignin’s dispersing agent. The resulting composites were investigated for both their mechanical properties and their melting point following the ASTM standards as well as their behaviour was compared with neat LDPE. The results reveal that addition of compatibilizer significantly improved the mechanical properties of lignin, yielding closer values to those of neat LDPE. In fact, the addition of 3% maleated polyethylene induced a 37% increase of the Young’s modulus, whilst 3% CuSO 4 ·5H 2 O provides a good lignin dispersion. The above observations are further supported by the scanning electron micrographs of the blend specimens. Finally, the differential scanning calorimetry analysis revealed that the melting temperature and the crystallinity of LDPE slightly increase with the addition of 3% CuSO 4 ·5H 2 O.