Evaluating the cell structure‐impact damping relation of cross‐linked polyethylene foams by falling weight impact tests

Abstract

This study examines the effect of foam thickness on impact damping properties of closed-cell cross-linked polyethylene foams of different densities. Compression tests and falling weight impact tests were performed to detect the most important mechanisms, which affect the mechanical properties of the foams. The results showed that impact damping properties are significantly influenced by foam thickness, while energy-absorbing capability primarily depends on foam density. The average cell diameter was determined with a

Polymer foams as advanced energy absorbing materials for sports applications—A review

“…In this regard, Lyn and Mills showed that a relaxation time of 10 min between two drops is sufficient for a rebonded polyurethane foam to recover without residual deformation 81 . In contrast, in our previous study 56 on weakly crosslinked polyethylene foams, we found an opposing phenomenon. The impact tests repeated every minute resulted in a deterioration in the energy absorption and impact damping capability.…”

“…Once the opposite cell walls meet, the so‐called densification zone starts, where the stress level starts to increase steeply. In this case, the foam behaves as a solid polymer material 14,56,91–93 …”

“…If the deformation during the load is too high and the densification zone is reached, the foam product will not perform its function properly, and the risk of health damage increases. Therefore, it is important to optimize the thickness of the foam: a too‐thin foam is dangerous due to the compaction zone, while a too‐thick foam increases the production cost due to the amount of matrix material required 6,8,56 …”

“…The impact tests repeated every minute resulted in a deterioration in the energy absorption and impact damping capability. The repetitive drops caused irreversible deformations on the foam walls during the impact, thus permanently reducing the mechanical properties of the foam 56 …”

“…Increased thickness is also a limiting factor for breathability, as water vapor needs to take a longer distance from the inside to the outside surface of the clothing. However, higher thickness results in better impact damping capability, 56 and both factors need to be considered in the designing process of protective equipment.…”