Fibers are functional fillers that replace carbon black and provide superior properties through fiber bonding to the rubber matrix. The Formulation Program of Finite Fiber’s Technical Services provides assistance in the modification of existing formulations to accommodate the addition of cut fibers.

We have found that in a generic black SBR formulation that 10 phr of N330(HAF) carbon black can be replaced by 2 – 3 phr of short fibers (2 – 8 mm cotton, polyester, or nylon) to yield a resultant rubber compound of comparable cured hardness. While not all rubber filler materials (clay, silica, whiting, carbon black, etc.) behave equally in all polymers, we have concluded that for conservative loadings of short fibers this replacement relationship
is adequate.

The process begins when a company provides Finite Fiber with a starting point formulation. A formulation review is performed and the formula is modified to accommodate the loading of short fibers to improve the desired physical properties while maintaining other physical property requirements of the original formulation. If a blend of fillers are used, there will be a partial replacement of both fillers, but both fillers will still be in the same ratio to one another. If there are silica coupling agent(s) used with certain silica fillers, the loading of these coupling agents will be changed (lowered) to reflect the new loading of the reactive
silica filler.

In some cases the relationship of the plasticizer to the total filler surface area will be considered and modified proportionally as the total filler loading of the compound is decreased for the addition of short fibers.

As formulations are reviewed, other ingredients or levels of ingredients that are questionable in regards to obsolescence, effectiveness, cost, processability, etc. will be noted and recommendations will be made.

The intent is for Finite Fiber to work with companies to help them fairly evaluate the reinforcement advantages of using cut fibers in their rubber or plastic formulations.

Fibers are functional fillers that replace carbon black and provide superior properties through fiber bonding to the rubber matrix.