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Article: Diffusion-limited hydrolysis in polymeric materials

Linde, Erik / Giron, Nicholas H. / Celina, Mathew C.

Elsevier Ltd Polymer degradation and stability. 2022 Oct., v. 204

2022

Abstract: Polymer degradation under aggressive environmental stressors often develops heterogeneities due to diffusion-limited reaction phenomena. This is well established for diffusion-limited oxidation (DLO), which is known to occur for most polymeric materials ... ...

Abstract	Polymer degradation under aggressive environmental stressors often develops heterogeneities due to diffusion-limited reaction phenomena. This is well established for diffusion-limited oxidation (DLO), which is known to occur for most polymeric materials at elevated temperatures but has been less summarized for the conditions of diffusion-limited hydrolysis (DLH). An overview of hydrolysis for several materials and a computational model, analogous to the underlying equations for DLO, able to define this diffusion-reaction system is presented. A systematic study of the influence of various parameters, such as water diffusivity, reaction rate and order, and a more in-depth focus on residual isocyanate hydrolysis in a polymeric methylene diphenyl diisocyanate (pMDI) based polyurethane (PU) foam is given. For this system, we present experimental data for model ‘input’ parameters and discuss predictions for different conditions. We conceptually compare the behavior of diffusion-limited oxidation to that of diffusion-limited hydrolysis (DLH). With the mathematical framework and key material properties presented herein, any DLH phenomena following Fickian diffusion behavior can be understood, modeled, and predicted.
Keywords	bioinformatics ; biphenyl ; degradation ; diffusivity ; foams ; hydrolysis ; models ; oxidation ; polyurethanes
Language	English
Dates of publication	2022-10
Publishing place	Elsevier Ltd
Document type	Article
ZDB-ID	1502217-1
ISSN	0141-3910
ISSN	0141-3910
DOI	10.1016/j.polymdegradstab.2022.110095
Database	NAL-Catalogue (AGRICOLA)

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Article: Time- and Feedback-Dependent DLO Phenomena in Oxidative Polymer Aging

Linde, Erik / Nilsson, Fritjof / Barrett, Matija / Hedenqvist, Mikael S / Celina, Mathew C

Polymer degradation and stability. 2021 July, v. 189

2021

Abstract: Polymer degradation under oxidative conditions, particularly under accelerated stresses such as increased temperatures and irradiation, often exhibits spatially heterogeneous oxidation profiles. This well-known behavior is the result of diffusion-limited ...

Abstract	Polymer degradation under oxidative conditions, particularly under accelerated stresses such as increased temperatures and irradiation, often exhibits spatially heterogeneous oxidation profiles. This well-known behavior is the result of diffusion-limited oxidation (DLO), which occurs when the oxidation rate is faster than the resupply of oxygen through diffusion into the material. So far most theoretical model descriptions have focused on DLO in equilibrium situations in which the underlying material properties do not change with increasing degradation levels or are constant (i.e. time-independent) variables. An extension of a previously developed finite element model is now presented, which accommodates time-dependent variables that are either explicitly time-dependent (i.e. changes homogeneously throughout the material), or through a feedback mechanism driven by the localized degree of oxidation, which results in spatial variations in the material properties responsible for specific DLO behavior. This model is realized in COMSOL Multiphysics and is capable of geometries in 1D up to 3D. Additionally, specific theoretical cases in 1D are shown which relate to known non-stationary phenomena in polymer degradation. They illustrate the effect on the resulting oxidation profile, when the oxygen diffusivity, solubility or oxidation rate properties change over time and in space. With COMSOL based FEM, it is now possible to model DLO for whatever material behavior may exist or could be envisaged.
Keywords	accelerated aging ; chemical degradation ; chemical equilibrium ; diffusivity ; oxidation ; oxygen ; polymers ; solubility
Language	English
Dates of publication	2021-07
Publishing place	Elsevier Ltd
Document type	Article
Note	golden set
ZDB-ID	1502217-1
ISSN	0141-3910
ISSN	0141-3910
DOI	10.1016/j.polymdegradstab.2021.109598
Database	NAL-Catalogue (AGRICOLA)

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Article: Extended use of face masks during the COVID-19 pandemic - Thermal conditioning and spray-on surface disinfection

Celina, Mathew C / Martinez, Estevan / Omana, Michael A / Sanchez, Andres / Wiemann, Dora / Tezak, Matthew / Dargaville, Tim R

Polymer degradation and stability. 2020 Sept., v. 179

2020

Abstract: The current COVID-19 pandemic has resulted in globally constrained supplies for face masks and personal protective equipment (PPE). Production capacity is limited in many countries and the future course of the pandemic will likely continue with shortages ...

Abstract	The current COVID-19 pandemic has resulted in globally constrained supplies for face masks and personal protective equipment (PPE). Production capacity is limited in many countries and the future course of the pandemic will likely continue with shortages for high quality masks and PPE in the foreseeable future. Hence, expectations are that mask reuse, extended wear and similar approaches will enhance the availability of personal protective measures. Repeated thermal disinfection could be an important option and likely easier implemented in some situations, at least on the small scale, than UV illumination, irradiation or hydrogen peroxide vapor exposure. An overview on thermal responses and ongoing filtration performance of multiple face mask types is provided. Most masks have adequate material properties to survive a few cycles (i.e. 30 min disinfection steps) of thermal exposure in the 75°C regime. Some are more easily affected, as seen by the fusing of plastic liner or warping, given that preferred conditioning temperatures are near the softening point for some of the plastics and fibers used in these masks. Hence adequate temperature control is equally important. As guidance, disinfectants sprayed via dilute solutions maintain a surface presence over extended time at 25 and 37°C. Some spray-on alcohol-based solutions containing disinfectants were gently applied to the top surface of masks. Neither moderate thermal aging (less than 24 h at 80 and 95°C) nor gentle application of surface disinfectant sprays resulted in measurable loss of mask filter performance. Subject to bio-medical concurrence (additional checks for virus kill efficiency) and the use of low risk non-toxic disinfectants, such strategies, either individually or combined, by offering additional anti-viral properties or short term refreshing, may complement reuse options of professional masks or the now ubiquitous custom-made face masks with their often unknown filtration effectiveness.
Keywords	COVID-19 infection ; degradation ; disinfectants ; disinfection ; face ; face masks ; filtration ; hydrogen peroxide ; irradiation ; pandemic ; risk ; safety equipment ; temperature ; ultraviolet radiation ; vapors ; viruses
Language	English
Dates of publication	2020-09
Publishing place	Elsevier Ltd
Document type	Article
Note	NAL-AP-2-clean
ZDB-ID	1502217-1
ISSN	0141-3910
ISSN	0141-3910
DOI	10.1016/j.polymdegradstab.2020.109251
Database	NAL-Catalogue (AGRICOLA)

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Article: Thermoset materials characterization by thermal desorption or pyrolysis based gas chromatography-mass spectrometry methods

Campbell, C. Garrett / Astorga, Dominik Jordon / Duemichen, Erik / Celina, Mathew

Polymer degradation and stability. 2020 Apr., v. 174

2020

Abstract: ... behavior over the temperature range (80–125 °C) studied, in agreement with oxidation sensitivies based ...

Abstract	Thermoset materials characterization is often limited to solid state analytical techniques such as IR, NMR, DSC, TGA and mechanical testing. Alternatively, their off-gassing behavior can also be evaluated using GC based techniques such as TD-GC-MS, allowing this method to be applied to thermoset materials analyses such as identification, aging characterization, and formulation optimization. As an overview, common thermoset materials were evaluated by analyzing their gaseous degradation products via TGA-based pyrolysis and subsequent TD-GC-MS for the identification of representative volatile signatures. It is thereby possible to distinguish different classes of phenolic materials or cured epoxy resins, as well as their amine or anhydride curatives. Additionally, this method enabled quantification of a volatile fragment (bisphenol A, BPA) which is associated with oxidation of epoxy/amine thermoset materials. The amount of evolved BPA increased linearly with aging time and this trend exhibits linear Arrhenius behavior over the temperature range (80–125 °C) studied, in agreement with oxidation sensitivies based on oxygen consumption data. Further, TD-GC-MS was used to explore how off-gassing of residual anhydride curative from an epoxy/anhydride material depends on formulation stoichiometry. Even in formulations that theoretically contained enough epoxy to consume all anhydride (1:1 stoichiometry), an imperfect final cure state resulted in residual anhydride which could evolve from the material. For such materials, a slightly epoxy-rich formulation is required to ensure that the material contains no residual unreacted anhydride. Analysis of volatiles generated by thermal exposure is an attractive characterization approach enabling compositional analysis as well as complementary diagnostics for materials degradation.
Keywords	anhydrides ; bisphenol A ; desorption ; diagnostic techniques ; differential scanning calorimetry ; epoxides ; gas chromatography-mass spectrometry ; mechanical testing ; nuclear magnetic resonance spectroscopy ; oxidation ; oxygen consumption ; pyrolysis ; resins ; stoichiometry ; temperature ; thermogravimetry
Language	English
Dates of publication	2020-04
Publishing place	Elsevier Ltd
Document type	Article
ZDB-ID	1502217-1
ISSN	0141-3910
ISSN	0141-3910
DOI	10.1016/j.polymdegradstab.2019.109032
Database	NAL-Catalogue (AGRICOLA)

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Book ; Conference proceedings: Polymer degradation and performance

Celina, Mathew C

(ACS symposium series ; 1004)

2009

Institution	American Chemical Society / Division of Polymer Chemistry
Event/congress	American Chemical Society (ACS) spring meeting (2007.03, ChicagoIll.) ; Symposium on Polymer Performance Degradation and Materials Selection (2007.03, ChicagoIll.)
Author's details	sponsored by the Division of Polymer Chemistry. Mathew C. Celina, ed
Series title	ACS symposium series ; 1004
Keywords	Biopolymers ; Polymers ; Polymers/Deterioration
Language	English
Size	XII, 331 S.
Publisher	American Chemical Soc
Publishing place	Washington, DC
Document type	Book ; Conference proceedings
ISBN	9780841269781 ; 0841269785
Database	Library catalogue of the German National Library of Science and Technology (TIB), Hannover

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Article: Extended use of face masks during the COVID-19 pandemic - Thermal conditioning and spray-on surface disinfection.

Celina, Mathew C / Martinez, Estevan / Omana, Michael A / Sanchez, Andres / Wiemann, Dora / Tezak, Matthew / Dargaville, Tim R

Polymer degradation and stability

2020 Volume 179, Page(s) 109251

Abstract	The current COVID-19 pandemic has resulted in globally constrained supplies for face masks and personal protective equipment (PPE). Production capacity is limited in many countries and the future course of the pandemic will likely continue with shortages for high quality masks and PPE in the foreseeable future. Hence, expectations are that mask reuse, extended wear and similar approaches will enhance the availability of personal protective measures. Repeated thermal disinfection could be an important option and likely easier implemented in some situations, at least on the small scale, than UV illumination, irradiation or hydrogen peroxide vapor exposure. An overview on thermal responses and ongoing filtration performance of multiple face mask types is provided. Most masks have adequate material properties to survive a few cycles (i.e. 30 min disinfection steps) of thermal exposure in the 75°C regime. Some are more easily affected, as seen by the fusing of plastic liner or warping, given that preferred conditioning temperatures are near the softening point for some of the plastics and fibers used in these masks. Hence adequate temperature control is equally important. As guidance, disinfectants sprayed via dilute solutions maintain a surface presence over extended time at 25 and 37°C. Some spray-on alcohol-based solutions containing disinfectants were gently applied to the top surface of masks. Neither moderate thermal aging (less than 24 h at 80 and 95°C) nor gentle application of surface disinfectant sprays resulted in measurable loss of mask filter performance. Subject to bio-medical concurrence (additional checks for virus kill efficiency) and the use of low risk non-toxic disinfectants, such strategies, either individually or combined, by offering additional anti-viral properties or short term refreshing, may complement reuse options of professional masks or the now ubiquitous custom-made face masks with their often unknown filtration effectiveness.
Keywords	covid19
Language	English
Publishing date	2020-06-04
Publishing country	England
Document type	Journal Article
ZDB-ID	1502217-1
ISSN	0141-3910
ISSN	0141-3910
DOI	10.1016/j.polymdegradstab.2020.109251
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article: High temperature polymer degradation: Rapid IR flow-through method for volatile quantification

Giron, Nicholas H / Mathew C. Celina

Polymer degradation and stability. 2017 Nov., v. 145

2017

Abstract: Accelerated aging of polymers at elevated temperatures often involves the generation of volatiles. These can be formed as the products of oxidative degradation reactions or intrinsic pyrolytic decomposition as part of polymer scission reactions. A simple ...

Abstract	Accelerated aging of polymers at elevated temperatures often involves the generation of volatiles. These can be formed as the products of oxidative degradation reactions or intrinsic pyrolytic decomposition as part of polymer scission reactions. A simple analytical method for the quantification of water, CO2, and CO as fundamental signatures of degradation kinetics is required. This study describes an analytical framework and develops a rapid mid-IR based gas analysis methodology to quantify volatiles that are contained in small ampoules after aging exposures. The approach requires identification of unique spectral signatures, systematic calibration with known concentrations of volatiles, and a rapid acquisition FTIR spectrometer for time resolved successive spectra. The volatiles are flushed out from the ampoule with dry N2 carrier gas and are then quantified through spectral and time integration. This method is sufficiently sensitive to determine absolute yields of ∼50 μg water or CO2, which relates to probing mass losses of less than 0.01% for a 1 g sample, i.e. the early stages in the degradation process. Such quantitative gas analysis is not easily achieved with other approaches. This approach opens up the possibility of quantitative monitoring of volatile evolution as an avenue to explore polymer degradation kinetics and its dependence on time and temperature.
Keywords	accelerated aging ; carbon dioxide ; carbon monoxide ; Fourier transform infrared spectroscopy ; monitoring ; polymers ; spectrometers ; temperature
Language	English
Dates of publication	2017-11
Size	p. 93-101.
Publishing place	Elsevier Ltd
Document type	Article
ZDB-ID	1502217-1
ISSN	0141-3910
ISSN	0141-3910
DOI	10.1016/j.polymdegradstab.2017.05.013
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Extended use of face masks during the COVID-19 pandemic - Thermal conditioning and spray-on surface disinfection

Celina, Mathew C. / Martinez, Estevan / Omana, Michael A. / Sanchez, Andres / Wiemann, Dora / Tezak, Matthew / Dargaville, Tim R.

Polymer Degradation and Stability

2020 Volume 179, Page(s) 109251

Keywords	Materials Chemistry ; Mechanics of Materials ; Polymers and Plastics ; Condensed Matter Physics ; covid19
Language	English
Publisher	Elsevier BV
Publishing country	us
Document type	Article ; Online
ZDB-ID	1502217-1
ISSN	0141-3910
ISSN	0141-3910
DOI	10.1016/j.polymdegradstab.2020.109251
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article: A perspective on the inherent oxidation sensitivity of epoxy materials

Celina, Mathew C / Dayile, Angela R / Quintana, Adam

Polymer. 2013 June 7, v. 54, no. 13

2013

Abstract: ... °C. Excellent Arrhenius behavior was observed with activation energies in the 70–80 kJ/mol range ...

Abstract	There has long been awareness that epoxy materials are not inert to high temperature-induced degradation and therefore have performance limits. As organic polymers, epoxy thermo-sets and composite materials will degrade under thermo-oxidative conditions with loss of useful properties in adhesion or mechanical toughness, and this degradation may initiate at the surface. While high temperature empirical data on the depth of degradation profiles have been made available for some materials, precise data on the intrinsic oxidation sensitivity of epoxy materials do not yet exist. Two different epoxy material types were chosen: a DGEBA based resin (Epon 828) was cured with either a cycloaliphatic amine (Ancamine 2049) or a polyether amine (Jeffamine D230) for comparison. Due to generally low O₂ permeability in epoxies any oxidation will be limited to the surface; hence experiments were conducted for thin films under non-diffusion limited conditions to obtain unbiased rate data. We have succeeded to show for the first time that oxidation behavior of epoxies at moderate temperatures can be approached experimentally. This study offers an overview on the intrinsic oxidation sensitivity of two cured epoxy thermo-set materials between 25 and 140 °C. Excellent Arrhenius behavior was observed with activation energies in the 70–80 kJ/mol range. These epoxy materials are surprisingly reactive and show higher oxidation rates than anticipated, even at moderate temperatures. In any applications where epoxy materials are used at elevated temperatures under non-inert conditions, oxidation will result in material chemistry changes and this will affect their performance with regard to adhesion or properties in composites.
Keywords	adhesion ; composite materials ; epoxides ; oxidation ; permeability ; polymers ; temperature
Language	English
Dates of publication	2013-0607
Size	p. 3290-3296.
Publishing place	Elsevier Ltd
Document type	Article
ISSN	0032-3861
DOI	10.1016/j.polymer.2013.04.042
Database	NAL-Catalogue (AGRICOLA)

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Article: Extended use of face masks during the COVID-19 pandemic - Thermal conditioning and spray-on surface disinfection

Celina, Mathew C. / Martinez, Estevan / Omana, Michael A. / Sanchez, Andres / Wiemann, Dora / Tezak, Matthew / Dargaville, Tim R.

Polym Degradation Stab

Abstract	The current COVID-19 pandemic has resulted in globally constrained supplies for face masks and personal protective equipment (PPE). Production capacity is limited in many countries and the future course of the pandemic will likely continue with shortages for high quality masks and PPE in the foreseeable future. Hence, expectations are that mask reuse, extended wear and similar approaches will enhance the availability of personal protective measures. Repeated thermal disinfection could be an important option and likely easier implemented in some situations, at least on the small scale, than UV illumination, irradiation or hydrogen peroxide vapor exposure. An overview on thermal responses and ongoing filtration performance of multiple face mask types is provided. Most masks have adequate material properties to survive a few cycles (i.e. 30 min disinfection steps) of thermal exposure in the 75°C regime. Some are more easily affected, as seen by the fusing of plastic liner or warping, given that preferred conditioning temperatures are near the softening point for some of the plastics and fibers used in these masks. Hence adequate temperature control is equally important. As guidance, disinfectants sprayed via dilute solutions maintain a surface presence over extended time at 25 and 37°C. Some spray-on alcohol-based solutions containing disinfectants were gently applied to the top surface of masks. Neither moderate thermal aging (less than 24 h at 80 and 95°C) nor gentle application of surface disinfectant sprays resulted in measurable loss of mask filter performance. Subject to bio-medical concurrence (additional checks for virus kill efficiency) and the use of low risk non-toxic disinfectants, such strategies, either individually or combined, by offering additional anti-viral properties or short term refreshing, may complement reuse options of professional masks or the now ubiquitous custom-made face masks with their often unknown filtration effectiveness.
Keywords	covid19
Publisher	WHO
Document type	Article
Note	WHO #Covidence: #526748
Database	COVID19

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