Effect of gas‐phase tortuosity on the mechanical properties of low‐density polyolefin open‐cell foams at low‐ and high‐strain rates

Abstract

This paper describes the mechanical behavior in compression, at both low-and high-strain rates, of several low-density open-cell polyolefin-based foams with different gas phase interconnectivities and different levels of gas-phase tortuosity. The mechanical properties of the open-cell polyolefin foams have been compared with two different references: an open-cell low tortuous foam based on flexible polyurethane and closed-cell polyolefin foams. One the one hand, at low-strain rates, it has been observed that the mechanical performance is controlled by the open-cell content and the properties of the polymeric matrix, being the influence of tortuosity small. On the other hand, the influence of the level of tortuosity is critical to high-strain rates. In fact, it has been demonstrated that open-cell polyolefin foams with high tortuosity (HT) present an unexpected mechanical behavior, showing excellent mechanical properties, which are even similar to that of closed-cell polyolefin materials with the same chemical composition. Therefore, low-density polyolefin foams with HT have a unique mechanical performance strongly influenced by the strain rate.

Green and High-Expansion PLLA/PDLA Foams with Excellent Thermal Insulation and Enhanced Compressive Properties

“…Thus, numerous nanosized cells appear on the large cell walls. The local open-cell structure could weaken the compressive mechanical properties of the PLLA foams. , For the PLLA/PDLA blend foams, no local open-cell structure can be observed in the wall because the cell walls are hard to be broken during the process of being stretched and thinned because of the reinforcement effect of the SC crystallites.…”

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

“…There are also several studies on the dynamic mechanical investigation of polymer foams, which primarily focus on the study of the effect of air between foam cells and foam density. Lopez Gonzalez et al 21 studied the effect of open‐cell content on same density low density polyethylene and ethylene‐vinyl acetate foams and showed that at high deformation rates, an open‐cell foam with high tortuosity approaches the properties of closed‐cell foams, wherein the compression of gas in the cells improves the shock‐absorbing capability of the foam. (Tortuosity gives the required distance, which a gas molecule has to move to get from one side of the foam to the other).…”

Experimental Study of Loaded Foams During Free Fall Investigation and Evaluation of Microstructure

“…The particles of Zinc Oxide act as colloidal particles, encouraging the creation of additional bubbles, and this appears to rise with filler content. Increasing viscosity appears to impede cell growth [19,20], lower concentration foams allow for easier cell growth, resulting in a lower final foam density [29]. The vacancy percentage and filling content impact foam density [30].…”

“…It is similar to foams with closed cells in that the gas in cells compresses, enhancing the foam's shock-absorbing ability (Lopez Gonzalez. [19]). (A gas-phase must travel a long distance to traverse a foam.)…”