Modern polymer materials have to fulfill increasing requirements on application specific properties. The reactive blending of polymers is a powerful and efficient tool to prepare multiphase polymer blends with exceptional properties. In state of the art reactive blending, the chemical reaction is induced by temperature sensitive initiators. Thus, it is difficult to precisely control the desired chemical reaction and to manage the changed viscosity of molten polymer blends. At the Leibniz Institut fuer Polymerforschung Dresden e.V. (IPF), electron-induced reactive processing (EIReP) was developed in order to overcome the disadvantages of state of the art reactive blending by its tunable energy inputs from high energy electrons.
Engineering plastics have unique attributes such as excellent tensile strength, modulus, stiffness, high chemical resistance, electrical properties, low friction, dimensional stability and low creep. Consequently, these materials are good candidates for several industrial applications. Unfortunately, these high-performance plastics are facing a number of difficulties to becoming commercially and economically available owing to major issues of processing ability, cost and toughness.
Researchers lead by Dr. Uwe Gohs from IPF, Germany, for the first time, prepared high performance polyamide 6 elastomeric blends. This is stemming from the successful preparation of high performance polyolefin based blends by EIReP. Their work is now published in a peer-reviewed journal, European Polymer Journal.
The authors did tensile tests of pristine polymers and polyamide 6 (PA6)/fluoroelastomer (FKM) blends using dumbbell shaped tests specimens. They analyzed the high temperature properties of pristine polymers and their blends using a thermogravimetric (TGA) analyzer and performing swelling experiments. TGA analysis was performed at a temperature range of 30-700 0C under nitrogen atmosphere. Circular tests specimens were obtained from compression molded plates in order to perform swelling test. These samples were weighed and immersed in oil for 72 hrs. At the end of the swelling time, the specimens were removed from the testing oil, blotted and weighed in a glass-stoppered bottle.
The prominent factors affecting the morphology of immiscible polymer blends were blend composition, thermodynamic compatibility, viscosity mismatch, processing conditions, and interfacial tension. The researchers did a careful selection of raw materials, after which they systematically varied the dose during EIReP while keeping constant other parameters used for the preparation of high performance polyolefin based blends. Owing to mixing at dynamic conditions, a wide distribution of the dispersed domain size was observed. However, the domain size was comparatively larger for the unmodified blends as compared to EIReP modified blends.
The authors reported for the first time a successful preparation of high performance polyamide 6/ fluoroelastomer blends using EIReP. The modified blends exhibited superior mechanical strength, good thermal stability as well as exceptional oil swelling resistance. The volume swell of the specimens was limited to 5-8 % by volume in IRM oil at150 °C. The authors observed that this was even the lowest value among rubber-plastic blends. The improved mechanical as well as thermal attributes of the blends are based on reduced interfacial tension between phase components, an increased interfacial area and long chain branching of the PA6 after EIReP. The authors found that this was a promising approach to designing new high-performance and cost-efficient polymer blends by sustainable electron-induced reactive processing without the use of chemical additives, solvents and/or reaction initiators.
Shib Shankar Banerjee, Carsten Zschech, Uwe Gohs, and Gert Heinrich. Design and properties of high-performance polyamide 6/fluoroelastomer blends by electron-induced reactive processing. European Polymer Journal, volume 85 (2016), pages 508518.
Leibniz-Institut für Polymerforschung Dresden e.V., D-01069 Dresden, Germany.Go To European Polymer Journal