Regulation of rheological and mechanical properties of polypropylene compositions for automotive parts

• Main Authors: Svetlana Saitarly, Viktoriia Plavan, Nataliia Rezanova, Nadiya Sova
• Format: Article
• Language: English
• Published: PC Technology Center 2018-05-01
• Series: Tehnologìčnij Audit ta Rezervi Virobnictva
• Subjects: polypropylene; calcite concentrate; propylene-octenoic block copolymers; rheological properties; mechanical properties; impact strength; autimotive parts
• Online Access: http://journals.uran.ua/tarp/article/view/152056
• ISSN: 2226-3780; 2312-8372

The object of research is the technology of producing filled impact-resistant compositions based on polypropylene for the manufacture of automotive parts. The main problem is the reduction of strength and technical characteristics with an increase in the amount of filler in the compositions. To solve this problem, the injection of a modifier in an amount of 5 mass % is proposed in filled polypropylene compositions. The effect of the filler and modifier on the rheological and mechanical properties of polypropylene-based compositions has been studied. It has been established that the presence of calcite concentrate as a filler and propylene-octenoic block copolymers as a modifier in the composition helps to reduce its viscosity, which is due to the predominant effect of the emulsifying action of calcium stearate over the thickening effect of the mineral filler. An increase in the melt flow index in compositions with 5 % propylene-octenoic block polymer is shown, which is explained by its plasticizing effect and good combination with polypropylene. It is shown that the injection of the filler to 10 mass % increases the impact strength compared to the original polypropylene. A further increase in the filler content to 20 % in the compositions reduces the impact strength to almost the value for the output polypropylene with an uncritical decrease in tensile strength. It is shown that the presence of 5 mass % of the modifier in the compositions increases the value of the relative elongation. It is determined that the developed composition with 5 mass % of the modifier and with varying the amount of filler can be used for the production of parts for cars for various purposes without significant changes in the technological cycle. The advantage of the investigated compositions is the reduction of energy consumption for the processing of highly filled compositions. The implementation of the developed technologies does not require additional capital investments for the re-equipment of the enterprise, since the developed compositions can be processed using conventional extrusion equipment.