Thermoplastic vulcanizates (TPVs) combine the elastic properties of thermoset cross-linked rubbers with the melt processability of thermoplastics. The most representative examples of this class are the TPVs based on polypropylene (PP) and ethylene-propylenediene terpolymer rubber (EPDM). The PP/EPDM blends were produced by dynamic vulcanization in a continuous extrusion process. The influence of different peroxide concentrations was studied with regard to cross-link density, compression set, tensile strength/elongation at break and morphology. With increasing peroxide concentration, the cross-link density increases, leading to a reduction of the compression set by 50 %. The cross-linked blends show smaller dispersed EPDM particles than the uncured one. With a peroxide concentration between 0.2 and 0.6 % a maximum in tensile strength and elongation at break was found and with increasing peroxide concentration, the complex viscosity of the TPVs decreases. Compared to batch processes, the results show nearly the same trends.

Abstract. In the long term, renewable raw materials should be used as favorite materials for applications in the electronic industry, but very high specifications for substrate materials make the use of biopolymers in electronics difficult. In this work, thermoplastic lignin is used as renewable raw material for electronic applications, precisely for a substrate material for printed circuit boards (PCBs). The results show that lignin-based substrate materials in a thickness range of 0.5 mm respectively 0.8 mm can successfully be produced via film extrusion using a slot die followed by a calender unit. With a glass fiber reinforcement content of ~24 vol. %, the substrate material shows good mechanical behavior (tensile tests and falling dart tests). The water absorption and the adhesion of the copper foil are in the range of FR 4, which is the standard substrate material for printed circuit boards. However, the maximum operating temperature, the time to delamination and the coefficient of thermal expansion are below the values of FR 4. Nevertheless, the developed lignin based substrate material can successfully be used as a prototype circuit board in a non-automated process.

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