Fatigue crack growth resistance of polyethylene compounds containing post-consumer recyclate for pipe applications

Description

Pipes made from high-density polyethylene (PE) are used in different fields of the infrastructure sector. For applications like water or gas distribution pipes or heating pipes, reliable performance is necessary. Therefore, the use of recycled plastics for these pressurized applications is controversial and, in many cases, forbidden. However, PE is also used in less demanding nonpressurized pipe applications like for sewage or drainage pipes, or for outer layers in district heating pipes. Although the use of recycled plastics is not prohibited in some ISO standards for piping systems, little amounts are currently used in the market. This is most likely a result of lacking experience and confidence in post-consumer recyclates. The purpose of this paper is to gain insights in the suitability of post-consumer recyclates to be used in compounds for pipe applications. Within this study, two commercially available PE recyclate grades consisting of post-consumer waste were acquired. Furthermore, these recyclates were used to produce compounds consisting of PE100-RC (PE pipe grade with an enhanced resistance to crack growth) and 25 m%, 50 m% and 75 m% of the respective recyclate. From the pure recyclates and the compounds, cracked round bar (CRB) specimen were produced and tested via cyclic loading to determine the resistance to fatigue crack growth at room temperature in air. Additionally, PE100-RC and PE80 were tested with the same method to allow for comparison. In this study, the aim was finding the highest possible recyclate content within the compound while still being able to reach similar fatigue crack growth performance as PE80. Depending on the recyclate grade, different compound formulations are feasible and the difference in fatigue crack growth resistance can be seen by comparing their crack growth kinetic curves with differences up to one decade in crack growth rate at similar stress intensity factors.

Period	29 Sept 2021
Event title	1st Virtual ESIS TC4 Conference on Fracture of Polymers, Composites and Adhesives
Event type	Conference
Location	AustriaShow on map