NATURAL FILLERS | ADDITIVES
Plant-based fillers and fibres
reduce carbon footprint Natural fillers and fibres from agricultural sources or wood- processing residues are sought after as alternative functional fillers. Jennifer Markarian finds out more
Plant-based fillers and fibres have long been used in natural fibre composites (NFC) and wood-plastic composites (WPC), and companies have investi- gated a wide range of materials as alternatives to mineral fillers. The ongoing quest for decarbonisa- tion has led to a renewed push for developing fillers that can help reduce carbon footprint while maintaining properties. Colorado, US-based Lignetics has introduced a
new, highly concentrated, non-dusting wood flour concentrate pellet that readily disperses in plastic compounding. The company has produced wood pellets, such as those used in pellet stoves for heating, for more than 30 years, and it has also supplied loose wood flour for WPC materials that can be used in durable goods such as decking, other building products, and automotive parts. This new pelletised product for plastics, the Lignetics Naturfil Wood Flour Concentrate, is more than 95% wood flour in a polymeric carrier. It is pelletised in a pellet mill rather than an extruder, in a low-cost, energy-efficient, US patent-pending process. Challenges with handling loose wood flour in plastics compounding include poor flowability, the
www.compoundingworld.com
difficulty of feeding a low bulk density filler and the risk of flammability associated with dust, said L.D. Sheftel, Category Director for wood flour at Lignetics. The new pellet form addresses these issues, achieves a higher concentration of wood flour than other available solutions, and is easily dispersed.
“Our pellet mill conditions for this new product
are designed to not exceed the glass transition temperature of lignin. Instead of the lignin binding the flour particles, the polymer carrier serves as the binder, which allows ready dispersion in plastic processing,” explained Frank Kvietok, Senior Director of R&D and Innovation at Lignetics. The pellet form has been used in twin-screw com- pounding extrusion and has been tested success- fully in a dry blend in a single-screw extruder, which indicates that it could be used directly in a mould- ing or part extrusion process.
As a functional filler for polymer composites, wood flour can reduce material cost, enhance stiffness and dimensional stability, and offer a natural appearance. The filler has a lower specific gravity than hemp fibre, glass fibre, or minerals
May 2025 | COMPOUNDING WORLD 13
Main image: FiberX corn stover at (left to right): 1/4” screen, 6 mesh, 40 mesh, 60 mesh and 100 mesh sizes
IMAGE: FIBERX
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56
