Reinforcement of polycaprolactone with microfibrillated lignocellulose

• We produced microfibrillated cellulose (MFLC) with high residual lignin content.
• We compared the reinforcement potential of MFLC with MFC from bleached pulp.
• We show that MFLC shows considerable advantages compared to MFC in the reinforcement of polycaprolactone films.
• We demonstrate that MFLC has some potential to serve as a replacement for chemically modified MFC in certain applications.

Cellulose-reinforced polycaprolactone (PCL) nanocomposite films were produced by casting from organic solvent. Microfibrillated cellulose derived from bleached pulp (MFC) and from pulp with high residual lignin content, termed microfibrillated lignocellulose (MFLC) were used as filler without any kind of chemical surface modification. Visual inspection revealed better dispersion of MFLC in organic solvent compared to MFC, resulting in a more homogeneous distribution of MFLC in PCL natrices compared to MFC. Tensile tests revealed an improvement of nanocomposite mechanical properties at 1% and diminishing performance at higher filler content. Overall, the performance of MFLC filler resulted in more favorable nanocomposite tensile performance than MFC. This was particularly true when MFLC was not continuously processed in solvent, but converted to a powder by drying from non-polar solvent prior to compounding with the polymer solution. Thus a novel dry nanocellulosic filler option for hydrophobic polymers obtained in a simple process is presented.