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2023
Conference Paper
Title
Investigation of the Mechanical - and Molecular Properties of Polypropylene Recyclat
Abstract
Due to the increasing demand for resource-efficient and sustainable products, recycling and the use of recycled materials are becoming more and more important. The so-called recyclates from the post-consumer- or industrial domestic waste is the resource efficient way of recycling plastics. Recyclates require up to 70 % less secondary energy for their processing than to produce virgin plastics. One of the greatest challenges of recyclates is, to provide them with constant material properties and quantities. For the use of recyclates in heavy loaded applications the materials must be optimized by several additives.
Material properties of recyclates form a domestic waste stream are published for static loading in several studies. Studies who investigate for example full factorial the static, cyclic and creep properties under different temperatures, aging conditions and mean stress ratios are not published or available now. Additionally, it is of great interest to get knowledge of the differences of the molecular structure of recyclat and virgin material.
In this paper a talc filled virgin and recyclat polypropylene (PP) was investigated concerning the mechanical and molecular properties. For the mechanical characterization static tension and fatigue tests on unnotched and notched specimens were carried out. Additionally, the aging effect at high temperature, the stress ratio, and temperatures at 23°C, 50 °C and 80 °C were investigated. The differences in the mechanical properties were described by analytical investigation. By the means of the fatigue investigation on specimen level two notch stress concepts (Highly Stressed Material Volume V80, Stress Gradient *) were used for the lifetime assessment (numerical calculation, part testing) of a door bearing pin of dish washer machine in household application. The lifetime assessment shows that virgin material of the dish washer can be replaced by the recyclat material. Based on an annual material requirement of 6,000 tons of material, a total of 2,500 tons of crude oil or 7,850 tons of CO2 can be saved.
Material properties of recyclates form a domestic waste stream are published for static loading in several studies. Studies who investigate for example full factorial the static, cyclic and creep properties under different temperatures, aging conditions and mean stress ratios are not published or available now. Additionally, it is of great interest to get knowledge of the differences of the molecular structure of recyclat and virgin material.
In this paper a talc filled virgin and recyclat polypropylene (PP) was investigated concerning the mechanical and molecular properties. For the mechanical characterization static tension and fatigue tests on unnotched and notched specimens were carried out. Additionally, the aging effect at high temperature, the stress ratio, and temperatures at 23°C, 50 °C and 80 °C were investigated. The differences in the mechanical properties were described by analytical investigation. By the means of the fatigue investigation on specimen level two notch stress concepts (Highly Stressed Material Volume V80, Stress Gradient *) were used for the lifetime assessment (numerical calculation, part testing) of a door bearing pin of dish washer machine in household application. The lifetime assessment shows that virgin material of the dish washer can be replaced by the recyclat material. Based on an annual material requirement of 6,000 tons of material, a total of 2,500 tons of crude oil or 7,850 tons of CO2 can be saved.
Author(s)