Tag: NCHR

Flexible Polyurethane Foams Modified with Novel Coconut Monoglycerides-Based Polyester Polyols

The products of the polyurethane (PU) industry such as foams, coatings and adhesives are numerous and can be found in many areas of everyday life. *

Polyols are an essential component in the production of polyurethane. Nowadays they mostly come from petroleum products. *

In view of potential risk factors such as the running out of fossil fuels, supply chain issues, environmental concerns and economic risks it is important to develop alternatives as substitutes and supplements to the existing petroleum derived polyols. *

Vegetable oils can be used to manufacture biobased polyols and various oils such as linseed oil, rapeseed oil, canola oil, grapeseed oil, corn oil, rice bran oil, palm oil, olive oil, castor oil and soybean oil have already been used to make polyols for different purposes.*

Most of the polyols derived from vegetable oils that are already commercially available are made from soybean and castor oil and are mainly used for rigid PU foam applications. *

So far biobased materials for flexible polyurethane foams (FPUFs) have not been studied as much as their rigid counterpart. This is because, due to their chemical composition, there are limits to how much biobased materials can be used in the flexible foam without having an undesired effect on the foam’s mechanical properties. *

Coconut oil is not often used to manufacture flexible foam because the coconut oil’s high level of saturation makes it less compatible with many common methods of creating polyols, as the widely used polyol-forming processes mostly rely on the unsaturation of vegetable oil for functionalization.

To make coconut monoglycerides (CMG) or other plant-based oils usable for polyol-forming processes they need to fulfil the same structural requirements as the fossil-based products. *

In the article “Flexible Polyurethane Foams Modified with Novel Coconut Monoglycerides-Based Polyester Polyols “ Christine Joy M. Omisol, Blessy Joy M. Aguinid, Gerson Y. Abilay, Dan Michael Asequia, Tomas Ralph Tomon, Karyl Xyrra Sabulbero, Daisy Jane Erjeno, Carlo Kurt Osorio, Shashwa Usop, Roberto Malaluan, Gerard Dumancas, Eleazer P. Resurreccion, Alona Lubguban, Glenn Apostol, Henry Siy, Arnold C. Alguno, and Arnold Lubguban describe how they investigated the potential of coconut monoglycerides (CMG) as a polyol raw material specifically for flexible polyurethane foam (FPUF) applications.*

The authors synthesized high-molecular-weight polyester polyols from coconut monoglycerides (CMG), a coproduct of fatty acid production from coconut oil, via polycondensation at different mass ratios of CMG with 1:5 glycerol:phthalic anhydride.*

The resulting CMG-based polyols were shown to work well in making flexible foam. *

Fourier transform infrared (FTIR) spectroscopy and atomic force microscopy (AFM) were used for the foam characterization. *

The modification of the foam formulation increased the monodentate and bidentate urea groups, shown using Fourier transform infrared (FTIR) spectroscopy, that promoted microphase separation in the foam matrix, confirmed using atomic force microscopy (AFM) and differential scanning calorimetry (DSC). *

Atomic force microscopy (AFM) was used to evaluate the hard–soft domains phase separation of the foam. *

The atomic force microscope was operated at a scan rate of 1.0 Hz in non-contact mode using NanoWorld Pointprobe® NCHR Silicon AFM probes for standard tapping mode applications. (typical resonance frequency 320 kHz, typical force constant 42 N/m). *

It could be shown that density of the CMGPOL-modified polyurethane foams (CPFs) decreased, while a significant improvement in their tensile and compressive properties was observed. *

The investigations by Christine Joy M. Omisol et al. resulted in a new sustainable polyol raw material that can be used to modify petroleum-based foam and produce flexible foams with varying properties that can be tailored to meet specific requirements. *

Figure 11 from Christine Joy M. Omisol et al (2024) “Flexible Polyurethane Foams Modified with Novel Coconut Monoglycerides-Based Polyester Polyols”:Atomic force microscopy (AFM) phase images of CMGPOL-modified polyurethane foams (CPF) and control foam measured with a size scan of 3 μm × 3 μm showing soft and hard regions represented by red and yellow colors, respectively. The foam samples in Figure 11 that exhibited a relatively high degree of microphase separation compared with other samples are CPF-8 and CPF-20. These foams appear to have relatively lighter areas of urea-rich regions separated more prominently from the darker, polyol-rich regions. In contrast, the control foam and CPF-16 show more dispersed hard and soft domains. CPF-24 and CPF-12 are at the middle of the scale, displaying light regions but with more dispersion than CPF-8 and CPF-20. These observations from the phase images of the foam samples are in agreement with the monodentate and bidentate urea contents of the samples, wherein the foams that exhibit greater H-bonding also manifest a higher degree of microphase separation. The same results were obtained by Baghban et al. NanoWorld Pointprobe® NCHR standard tapping mode/non-contact mode silicon AFM probes were used for the foam characterizations with atomic force microscopy.
Figure 11 from Christine Joy M. Omisol et al (2024) “Flexible Polyurethane Foams Modified with Novel Coconut Monoglycerides-Based Polyester Polyols”:
Atomic force microscopy (AFM) phase images of CMGPOL-modified polyurethane foams (CPF) and control foam measured with a size scan of 3 μm × 3 μm showing soft and hard regions represented by red and yellow colors, respectively.

*Christine Joy M. Omisol, Blessy Joy M. Aguinid, Gerson Y. Abilay, Dan Michael Asequia, Tomas Ralph Tomon, Karyl Xyrra Sabulbero, Daisy Jane Erjeno, Carlo Kurt Osorio, Shashwa Usop, Roberto Malaluan, Gerard Dumancas, Eleazer P. Resurreccion, Alona Lubguban, Glenn Apostol, Henry Siy, Arnold C. Alguno, and Arnold Lubguban
Flexible Polyurethane Foams Modified with Novel Coconut Monoglycerides-Based Polyester Polyols
ACS Omega 2024, 9, 4, 4497–4512
DOI: https://doi.org/10.1021/acsomega.3c07312

The article “Flexible Polyurethane Foams Modified with Novel Coconut Monoglycerides-Based Polyester Polyols” by Christine Joy M. Omisol, Blessy Joy M. Aguinid, Gerson Y. Abilay, Dan Michael Asequia, Tomas Ralph Tomon, Karyl Xyrra Sabulbero, Daisy Jane Erjeno, Carlo Kurt Osorio, Shashwa Usop, Roberto Malaluan, Gerard Dumancas, Eleazer P. Resurreccion, Alona Lubguban, Glenn Apostol, Henry Siy, Arnold C. Alguno and Arnold Lubguban is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third-party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit https://creativecommons.org/licenses/by/4.0/.

Feasibility of wear reduction for soft nanostructured thin film through enhanced elastic recoverability and contact stress relief

Over several decades many studies on the reduction of wear of mechanical systems have been conducted.
Methods to reduce wear are generally divided into the following categories: applying lubrication, coating with high-hardness materials, and surface texturing. *

Several studies have reported that coatings with higher hardness show more wear than those with lower hardness. From these reports, it is apparent that wear does not depend solely on the hardness of the surface.  Hence, there is a strong motivation for utilizing additional strategies for designing wear-resistive surfaces rather than only enhancing the hardness of the coating. *

In the article “Feasibility of wear reduction for soft nanostructured thin film through enhanced elastic recoverability and contact stress relief” Kuk-Jin Seo, Hyun-Joon Kim and Dae-Eun Kim show, that a soft, thin film comprising randomly aligned carbon nanotubes (CNTs) can reduce surface wear more effectively than a homogeneous thin film because of enhanced elastic recoverability and contact stress relief originating from its mesh structure. *

To investigate the wear characteristics of the mesh structure compared to those of the homogeneous thin film, multi-walled CNTs (MWCNTs) and diamond-like carbon (DLC) thin films were prepared to conduct nanoscale tribological experiments using atomic force microscopy (AFM). The MWCNT thin film showed unmeasurably low wear compared with the DLC thin film under a certain range of normal load. *

To demonstrate the wear reduction mechanism of the MWCNT thin film, its indentation and frictional behaviors were assessed. The indentation behavior of the MWCNT thin film revealed repetitive elastic deformation with a wide strain range and a significantly lower elastic modulus than that of the DLC thin film. The permanent deformation of the MWCNT thin film was observed through frictional experiments under relatively high normal load conditions. *

The presented results are expected to provide insights into the design of highly wear-resistant surfaces using nanostructures. *

The thickness and surface roughness of the MWCNT and DL thin films were measured using Atomic Force Microscopy. *

The force-displacement (F-D) curves were measured on the MWCNT thin film using the AFM to verify the mechanical behavior when indented by the zirconia microspheres that were used for wear and friction experiments. *

The adhesion forces between the thin films and zirconia microspheres were measured by observing the pull-off force of the F-D curve with the AFM. *

The adhesion force was measured using a colloidal AFM probe to aid the analysis of the tribological characteristics of the thin film. *

The pull-off forces for the DL specimens were obtained at 35 different locations with displacements of 50-200 nm. *

Diamond-coated AFM probes (NanoWorld Pointprobe® DT-NCHR ) were used for scanning, while non-coated silicon AFM probes with relatively high and low spring constants (NanoWorld Pointprobe® NCHR and CONTR) were used for the tribological experiments and specimen characterizations. *

Diamond-coated AFM probes (NanoWorld Pointprobe® DT-NCHR ) were used for scanning, while non-coated silicon AFM probes with relatively high and low spring constants (NanoWorld Pointprobe® NCHR and CONTR) were used for the tribological experiments and specimen characterizations.
Figure 6 from “Feasibility of wear reduction for soft nanostructured thin film through enhanced elastic recoverability and contact stress relief” by Kuk-Jin Seo et al.:
AFM images of wear tracks on the MWCNT thin film under test conditions of (a) 2,000 nN and 20,000 cycles, (b) 6,000 nN and 30,000 cycles, (c) 7,000 nN and 30,000 cycles, (d) 9,200 nN and 30,000 cycles, (e) 13,500 nN and 30,000 cycles, and (f) 28,000 nN and 30,000 cycles. Post-processed AFM images that subtracted the original image before each wear test under conditions of (g) 6,000 nN and 30,000 cycles, (h) 7,000 nN and 30,000 cycles, and (i) 28,000 nN and 30,000 cycles

*Kuk-Jin Seo, Hyun-Joon Kim and Dae-Eun Kim
Feasibility of wear reduction for soft nanostructured thin film through enhanced elastic recoverability and contact stress relief
Friction 11(7): 1292-1306 (2023)
DOI: https://doi.org/10.1007/s40544-022-0669-7

Please follow this external link to read the full article: https://rdcu.be/dejTa

The article “Feasibility of wear reduction for soft nanostructured thin film through enhanced elastic recoverability and contact stress relief” by Kuk-Jin Seo, Hyun-Joon Kim and Dae-Eun Kim is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third-party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit https://creativecommons.org/licenses/by/4.0/.

Atomistic insights into highly active reconstructed edges of monolayer 2H-WSe 2 photocatalyst

Today, October 9, 2022, is National #NanotechnologyDay in the US. The theme for this year’s National Nanotechnology Day is nanotechnology’s role in understanding and responding to climate change and improving the health of the Earth and its people.

Climate change has necessitated the framing of government regulations and the development of green strategies for reducing CO2 emissions. Scientists worldwide are engaged in efforts to find sustainable solutions to the problem of CO2 level in the air.*

Ascertaining the function of in-plane intrinsic defects and edge atoms is necessary for developing efficient low-dimensional photocatalysts.*

In their article “Atomistic insights into highly active reconstructed edges of monolayer 2H-WSe 2 photocatalyst” Mohammad Qorbani , Amr Sabbah, Ying-Ren Lai, Septia Kholimatussadiah, Shaham Quadir , Chih-Yang Huang, Indrajit Shown, Yi-Fan Huang, Michitoshi Hayashi, Kuei-Hsien Chen and Li-Chyong Chen report the wireless photocatalytic CO2 reduction to CH4 over reconstructed edge atoms of monolayer 2H-WSe2 artificial leaves.*

Their first-principles calculations demonstrate that reconstructed and imperfect edge configurations enable CO2 binding to form linear and bent molecules. Experimental results show that the solar-to-fuel quantum efficiency is a reciprocal function of the flake size. It also indicates that the consumed electron rate per edge atom is two orders of magnitude larger than the in-plane intrinsic defects. Further, nanoscale redox mapping at the monolayer WSe2–liquid interface confirms that the edge is the most preferred region for charge transfer.*

The author’s results pave the way for designing a new class of monolayer transition metal dichal-cogenides with reconstructed edges as a non-precious co-catalyst for wired or wireless hydrogen evolution or CO2 reduction reactions.*

The thickness of the WSe 2 flake was measured by using Atomic Force Microscopy with a NanoWorld Pointprobe® NCHR AFM probe and was controlled by a feedback mechanism. The AFM cantilever was driven under a resonant frequency of ~330 kHz and 42 N m−1 spring constant.*

Figure 4 from “Atomistic insights into highly active reconstructed edges of monolayer 2H-WSe2 photocatalyst” by Mohammad Qorbani et al: Nanoscale redox mapping and PC performance a FE-SEM image of the ML WSe2 in dark (control experiment) in the solution containing Ag ions. b FE-SEM images of the ML WSe2 under light after Ag photodeposition for 1 h, respectively. Bright regions show the presence of Ag nanoparticles. Inset illustrates the photoreduction mechanism. Scale bar = 2 μm. c–e AFM height profile measured in the liquid environment, background normalized SECM feedbacks maps for main, and lift scans, respectively. Scale bar = 1 μm. f Color map of the blank-corrected total methane yield as a function of flake sizes (in perimeters) and areas. g Blank-corrected IQE as a function of the average flake perimeter. The black line shows the fitted reciprocal curve. h Stability test for six cycles. Irradiation time for each cycle is 4 h. NanoWorld Pointprobe NCHR AFM probes were used for the atomic force microscopy
Figure 4 from “Atomistic insights into highly active reconstructed edges of monolayer 2H-WSe2 photocatalyst” by Mohammad Qorbani et al:
Nanoscale redox mapping and PC performance
a FE-SEM image of the ML WSe2 in dark (control experiment) in the solution containing Ag ions. b FE-SEM images of the ML WSe2 under light after Ag photodeposition for 1 h, respectively. Bright regions show the presence of Ag nanoparticles. Inset illustrates the photoreduction mechanism. Scale bar = 2 μm. c–e AFM height profile measured in the liquid environment, background normalized SECM feedbacks maps for main, and lift scans, respectively. Scale bar = 1 μm. f Color map of the blank-corrected total methane yield as a function of flake sizes (in perimeters) and areas. g Blank-corrected IQE as a function of the average flake perimeter. The black line shows the fitted reciprocal curve. h Stability test for six cycles. Irradiation time for each cycle is 4 h.

*Mohammad Qorbani , Amr Sabbah, Ying-Ren Lai, Septia Kholimatussadiah, Shaham Quadir , Chih-Yang Huang, Indrajit Shown, Yi-Fan Huang, Michitoshi Hayashi, Kuei-Hsien Chen and Li-Chyong Chen
Atomistic insights into highly active reconstructed edges of monolayer 2H-WSe 2 photocatalyst
Nature communications (2022) 13:1256
DOI:  https://doi.org/10.1038/s41467-022-28926-0

Please follow this external link to read the full article: https://rdcu.be/cXbA6

Open Access
The article “Atomistic insights into highly active reconstructed edges of monolayer 2H-WSe 2 photocatalyst” by Mohammad Qorbani , Amr Sabbah, Ying-Ren Lai, Septia Kholimatussadiah, Shaham Quadir , Chih-Yang Huang, Indrajit Shown, Yi-Fan Huang, Michitoshi Hayashi, Kuei-Hsien Chen and Li-Chyong Chen is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.