Aging behavior and lifetime assessment of polyolefin liner materials for seasonal heat storage using micro-specimen

摘要

The paper deals with the lifetime assessment of polyethylene (PE) and polypropylene (PP) liner materials for seasonal heat storages. Temperature loading profile was estimated for a storage type with maximum temperatures of 85 °C in September and minimum temperatures of 50 °C in March. Aging experiments in hot air or water at elevated temperatures were carried out using micro-sized specimen. The aging indicator strain-at-break was monitored. From experimental data at elevated temperatures endurance times at service-relevant temperatures were extrapolated using an Arrhenius approach. By weighting the endurance times with the loading profiles and assuming cumulative damages, lifetime values were deduced. The investigated PP random copolymer liner material exhibited a significant better long-term performance than the well-established PE liner material.