Natural Fiber Composites (NFC)
For thousands of years natural fibres were mankind’s primary material. Houses and ships were built of wood, while flax and hemp were used for making ropes and utilitarian fabrics such as sails and corn sacks. During the industrial revolution and in modern times, new applications have been developed with the use of chemical agents for bonding natural fibres into strong components for use in various industries.
Natural fibre composites are made with a thermoplastic or a thermosetting polymer matrix. The thermoplastics can be PE, PP, PS, PVC or PLA, while the thermosetting polymers are mainly acrylate, epoxide and phenol resins. The most important natural fibres used are flax, hemp, jute, kenaf, sisal, abaca and cotton. Other frequently used materials include wood fibre, sawdust and rice husks. In many cases, optimal bonding of the matrix and fibres is ensured by using adhesion promoters.
Indispensable for NFC compounding is perfect dispersive and distributive mixing at low product temperatures, in order to process the additives and typically high content of 30-70% natural fibres according to product specifications without thermally damaging the fibres. Also required are multiple feed points and if necessary the injection of liquid adhesion promoters at predetermined positions.
The Buss Kneader’s specific capabilities really come to the fore in these applications. Due to the operating principle, the enormous number of mixing cycles at moderate and uniform shear rates enables unsurpassed mixing efficiency and product quality at maximum throughput rates. As a side effect of the moderate shear rates, wear and tear is significantly lower than with other kinds of screw extruders. The process chamber is modularly designed by in-house experts according to specific applications.
The Buss Kneader’s two-stage system deliberately separates the compounding and pressure build-up stages so that each stage can be independently optimized. The hinged housing of the Buss Kneader and the retractable casing of the discharge extruder ensure fast and easy access for high system availability. Together with broadly based Buss process expertise, the modular design and therefore adaptable arrangement of the entire compounding line make the Buss Kneader first choice for compounding natural fibre composites.
Buss Kneader technology
Laboratory Kneader MX 30