Using Kraft Lignin by Solvent Mixing Technique in Wood Flour- Polypropylene Composites

In this study, the effect of Kraft lignin was investigated on the short term water absorption as well as mechanical properties in wood flour-polypropylene composites. Kraft lignin was extracted from black liquor by acidic method and mixed with the wood flour with ratio of 0, 2, 5 and 10 percent (based on wood flour dry weight) by solvent mixing method. The composites were manufactured by hot press method after mixing of the wood flour, the lignin, the polypropylene as well as the MAPP (0 and 2%) in internal mixer. The physical and mechanical properties of prepared samples were determined according to standard test methods. The results showed that the lignin improved physical and mechanical properties of the composites and it can be used as co-compatibilizer of MAPP in the wood plastic composites. The bending test results showed that in absence of MAPP, the composites with 10% lignin exhibited the highest flexural modulus and flexural strength. However at presence of MAPP, the composites with 5% lignin exhibited the highest flexural modulus and flexural strength. In absence and presence of MAPP, the composites with 10% lignin exhibited the lowest water absorption and the highest impact strength.