Mechanical response of hard bio-based PU foams under cyclic quasi-static compressive loading conditions

Hou, Chun‐Han; Czubernat, Kazimierz; Jin, Shichao; Altenhof, William; Maeva, E.; Seviaryna, Inna; Bandyopadhyay‐Ghosh, Sanchita; Sain, Mohini; Gu, Ruijun

doi:10.1016/j.ijfatigue.2013.09.012

Cited by 24 publications

(10 citation statements)

References 15 publications

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“…The slightly different behavior in the first loading− unloading cycle is usually observed in all elastomers. 38 In order to quantify the change in electical resistance of the GF-PDMS composite in response to external stimuli such as pressure, an impedance measurement device was coupled with the microtester, and its electrical resistance was measured while deforming the composite under cyclic compressive loading. Change in resistance of the composite at strains of 10%, 20%, and 30% are shown in Figure 3c.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Novel Graphene Foam Composite with Adjustable Sensitivity for Sensor Applications

Samad

Alhassan³

et al. 2015

ACS Appl. Mater. Interfaces

184

106

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In this study, free-standing graphene foam (GF) was developed by a three-step method: (1) vacuum-assisted dip-coating of nickel foam (Ni-F) with graphene oxide (GO), (2) reduction of GO to reduced graphene oxide (rGO), and then (3) etching out the nickel scaffold. Pure GF samples were tested for their morphology, chemistry, and mechanical integrity. GF mimics the microstructure of Ni-F while individual bones of GF were hollow, because of the complete removal of nickel. The GF-PDMS composites were tested for their ability to sense both compressive and bending strains in the form of change in electrical resistance. The composite showed different sensitivity to bending and compression. Upon applying a 30% compressive strain on the GF-PDMS composite, its resistance increased to ∼120% of its original value. Similarly, bending a sample to a radius of 1 mm caused the composite to change its resistance to ∼52% of its original resistance value. The relative change in resistance of the composite by an applied pressure/strain can be tuned to considerably different values by heat-treating the GF at different temperatures prior to infusing PDMS into its scaffold. Upon heat treating the GF at 800 °C prior to PDMS infusion, the GF-PDMS demonstrated ∼10 times better sensitivity than the untreated sample for a compressive strain of 20%. The composite was also tested for its ability to retain a change in electrical resistance when a brief load/strain is applied. The GF-PDMS composite was tested for at least 500 cycles under compressive cyclic loading and showed good electromechanical durability. Finally, it was demonstrated that the composite can be used to measure human blood pressure when attached to human skin.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Novel Graphene Foam Composite with Adjustable Sensitivity for Sensor Applications

Samad

Alhassan³

et al. 2015

ACS Appl. Mater. Interfaces

184

106

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“…This biocontent can be a reacting polyol or an inert filler. Modified vegetable oils (mainly castor oil 9–12 or soybean oil 4,13–16 ) are already used to partially replace petroleum based polyols in some applications. They are, in that case, reacting with the isocyanate.…”

Section: Introductionmentioning

confidence: 99%

Influence of lignin's pH on polyurethane flexible foam formation and how to control it

Maillard

Osso

Faye

et al. 2020

J of Applied Polymer Sci

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Low pH of commercial lignins has a catastrophic impact on the polyurethane foaming reactions. Experiments were performed with 10 wt% of lignin with various pHs in polyols. Virgin lignin (pH 2.5, 35% moisture) has the most negative impact as it reduces the initial foam rising rate by 85% and the foam's final height by 35% as compared to the reference foam, lignin free. Drying of this lignin at 80°C for 12 h can reduce this impact while alkaline treatment to bring the lignin's pH to 6.6 almost cancel it. As revealed by in situ dielectric constant measurements, both reactions, gelling via polymerization and blowing via CO2 degassing, are impacted. In situ Fourier transform infrared analysis of the foaming process demonstrated that blowing reaction is the most pH sensitive. Two methods to counter the pH influence by pH modification were tested and provide interesting results but also significant drawbacks limiting their applicability.

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“…Except for the first cycle no change in the hysteresis loop is seen for the rest, and it is demonstrated that the composite is intact up to 1000 cycles. The slightly different behavior in the first loading‐unloading cycle is a property of elastomers . A loading‐unloading cycle of GF‐PDMS composite, in compression, is shown in a sequence of photographs in Figure d showing it's cyclic behavior under compression.…”

mentioning

confidence: 99%

Graphene Foam Developed with a Novel Two‐Step Technique for Low and High Strains and Pressure‐Sensing Applications

Samad

Schiffer

et al. 2015

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Mechanical response of hard bio-based PU foams under cyclic quasi-static compressive loading conditions

Cited by 24 publications

References 15 publications

Novel Graphene Foam Composite with Adjustable Sensitivity for Sensor Applications

Novel Graphene Foam Composite with Adjustable Sensitivity for Sensor Applications

Influence of lignin's pH on polyurethane flexible foam formation and how to control it

Graphene Foam Developed with a Novel Two‐Step Technique for Low and High Strains and Pressure‐Sensing Applications

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