Short fibers-filled systems

Furthermore, various surface treatments are used in order to achieve the high performance. The methods of surface treatment for long fiber filled systems are the same ones as for short fiber filled systems, however the effect of the surface treatment on the rheological properties of long fiber filled composites is not imderstood enough yet. 

Nearly all micromechanics models for short-fibers filled systems consider the same basic assumptions ... 

A7.2 Halpin-Tsai Equations for Short Fibers Filled Systems Numerical Illustration... 

The notched Izod impact strength of the kenaf system is much lower than that of the glass fiber-filled PP but about the same as all other fillers and mica systems. Short fiber lengths present in the kenaf system due to the compounding system used and molding are probably responsible for the poor impact strengths [30]. 

Whilst finely grinding wood material may considerably hide the fiber aspect of wood particles, WPC exhibit properties which are typical of systems filled with short fibers of natural origin. As WPC is a rich subject in itself, only a few basic aspects will be discussed hereafter. It is obvious that not all thermoplastics can be used to prepare WPC. Indeed the polymer component melts or at least softens at or below the degradation point of the wood component, normally 200-220°C but must be rigid at normal usage temperatures (i.e., up to around 65°C). Practically, this reduces the choice to polypropylene, low-and high-density polyethylenes, polystyrene, and vinylics (essentially PVC). 

Extensive reviews on short fibers-reinforced elastomers have been published by Goettler and Shen, ° and more recently by Rajeev. Table 7.11 is a list of selected published works on natural fiber-filled rubber composites, sorted by rubber type. Only vulcanizable rubbers were considered in preparing the table thermoplastic rubber and rubber-plastics blends were omitted. As can be seen most grades of conventional elastomers have been considered with quite a large variety of natural fibers. Natural Rubber, SBR, and EPDM compounds have received much attention, as expected with respect to their industrial importance. A bonding system is us in most cases, with resin types (i.e. resorcinol-formaldehyde, resorcinol-hexamethylenetetramine, sil-ica-resorcinol-hexamethylenetetramine) the most frequent ones. 

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