Berstorff: Shear-Stretch Mixing Element for Twinscrew Extruders

Berstorff, Germany, has developed a new shear and stretch mixing element for compounding TPEs and continuous mixing of rubber in co-rotating twinscrew extruders. The screw geometry chosen influences the shear and elongation flow so decisively that the dispersion in the compound is improved, whilst at the same time the heating of the compound is less. In addition, it optimises the phase inversion occurring simultaneously in dynamically cross-linked TPE-Vs. In this combination of shear and elongation mixing elements, the compound is led into a flow channel, which is closed on the one side by the screw flights and on the other by a shearing and stretching flight. The compound is forced to flow over this shear-stretch flight. „This ensures that every part of the compound receives virtually the same degree of work, the danger of undispersed components in the form of specks and gels is minimised and the subsequent optimal dispersion of the material is guaranteed,” explained Dr Reinhard Uphus, Head of Development for Rubber & TPE Technology.

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