(612d) Lignin - Polypropylene Blends: Formulation and Performance

Lignin is a polyol and also polyphenol in plant stem and the second most abundant natural polymer coming only next to cellulose. It is an attractive biomass since it is readily available and relatively inexpensive. Currently lignin is mostly used to be burned for energy or to recover for chemicals.   Significant research interest has been focused on utilizing lignin as a polymer or filler since last century [1, 2]. However the properties of the lignin based composites by adding lignin as particulate filler to a second polymer are far from satisfactory, due to the complex and heterogeneous structure and chemistry of lignin which are highly dependent on the lignin sources and processing conditions.

In this study, lignin was used to replace partial PP by melt-blending of lignin with PP in a presence of different coupling agents using a twin screw extruder. The effects of lignin concentration and lignin type obtained from different sources and extraction processes on the morphology as well as rheology and mechanical and thermal properties of the lignin-PP blends were systematically investigated. The effect of coupling agent type and concentration on the blend performance was also evaluated. The results obtained indicate that with an appropriate formulation and processing conditions lignin can replace efficiently PP otherwise it can destroy badly the PP’s mechanical strength and ductility.