Effect of Conditioning on PU Foam Matrix Materials Properties

Abstract

This article deals with the characterization of the thermal-induced aging of soft polyurethane (PU) foams. There are studied thermal and mechanical properties by means of thermal analysis, tensile, compression and dynamic mechanical vibration testing. It was found in this study, that the increasing relative humidity of the surrounding atmosphere leads to the initiation of the degradation processes. This is reflected in the observed decreased mechanical stiffness. It is attributed to the plasticization of the PU foams wall material. It is in agreement with the observed increase of the permanent deformation accompanied simultaneously with the decrease of Young’s modulus of elasticity. The latter phenomenon is studied by the novel non-destructive forced oscillations vibration-damping testing, which is confirmed by observed lower mechanical stiffness thus indicating the loss of the elasticity induced by samples conditioning. In parallel, observed decreasing of the matrix hardness is confirming the loss of elastic mechanical performance as well. The effect of conditioning leads to the significant loss of the PU foam’s thermal stability.

Investigating the Effect of Relative Humidity on the Mechanics and Dynamics of Open‐Cell Polyurethane Auxetic Foams

“…Lapčík et al have indeed found that increased humidity causes initiation of degradation. [46] Like the tangent modulus, the PR shown in Figure 7d of both the 92% RH pristine and auxetic samples seem to be separated from the other specimens, despite the 15% RH pristine samples making this separation less obvious (Figure 7b). All values of the PR for the pristine samples are positive and the auxetic samples all show an NPR for most of the strain range.…”

“…Lapčík et al have recently investigated the effect of thermal and humidity conditioning on pristine PU foams. [ 46 ] Those authors found that conditioned foams became more compliant as the increased humidity caused the initiation of the degradation process. This shows the importance of similar testing on auxetic foams.…”

Polyborosiloxane-Encapsulated Carbon Nanotube/Polyurethane Foams for Multifunctional Pressure Memory and Pain Bionic Sensors

“…To give a response to mechanical compression, PU foam presents a light structure, with empty cell matrix geometry, that easily collapses under low-pressure regimes. 24 In recent years, PU foam has been widely used in e-skin for pressure detection due to its excellent elasticity, heat resistance, and biological harmlessness. 25 Huang et al 23 fabricated 3D lightweight piezoresistive sensing materials via surface coating the PU foam with hybrid CNT/ carbon black (CB) nanoparticles.…”

“…CNTs can be directly deposited on the surfaces of various polymer materials by solution processing technology, which is very important for the simplicity of the process. , Flexible and elastic polyurethane (PU) foam provides great advantages in the manufacture of pressure sensors. To give a response to mechanical compression, PU foam presents a light structure, with empty cell matrix geometry, that easily collapses under low-pressure regimes . In recent years, PU foam has been widely used in e-skin for pressure detection due to its excellent elasticity, heat resistance, and biological harmlessness. − Huang et al fabricated 3D lightweight piezoresistive sensing materials via surface coating the PU foam with hybrid CNT/carbon black (CB) nanoparticles.…”

Advanced Materials Structures for Sound and Vibration Damping

“…The effect of conditioning on the vibration damping of polyurethane (PU) foams, which were subjected to conditioning at two different temperatures (45 and 80 • C) and relative humidity values (45 and 80%) for different time intervals, was evaluated in [5]. It was found that the conditioning process had a significant influence on the properties of the tested PU foams.…”