Efficiency of processing stabilizers using a micro-oxygen uptake technique

Scheirs, John; Bigger, Stephen W.; Delatycki, O.

doi:10.1016/0032-3861(89)90298-x

“…At lower O 2 concentrations the total mass loss is greater, because less O 2 adds to the polymer during the reaction. O 2 uptake, measured by loss of O 2 in a constant volume gaseous system, has often been used as a direct measurement of the rate of oxidation on aliphatic polymers. − A typical reactive O 2 uptake rate on poly(ethylene) is ∼150–300 mL O 2 /g polymer, which corresponds to ∼210–430 mg O 2 /g polymer. − These data are often collected in the 100–180 °C range, similar to the experiments performed here. This means that the ∼12–17% net mass loss of PEI is an underestimate, and in reality, a larger mass fraction is lost.…”

Section: Resultsmentioning

confidence: 54%

Chemical Kinetics of the Autoxidation of Poly(ethylenimine) in CO₂ Sorbents

Nezam

¹

,

Xie²,

Golub

³

et al. 2021

ACS Sustainable Chem. Eng.

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The oxidative degradation rates of a CO 2 sorbent composed of a mesoporous alumina impregnated with poly-(ethylenimine) (PEI) are measured under systematically varied conditions and a reaction rate law is created. Good agreement is shown between the rate of oxidation obtained via in situ calorimetric heat measurement during oxidative degradation reactions and the loss of CO 2 capture performance presented as amine efficiency (mol CO 2 /mol amine). PEI mass loss and elemental composition are tracked over the course of the reaction and used in conjunction with the oxidation rate measurements to shed insight into the oxidation reaction(s). These data, in combination with measurements of the heat of reaction, suggest a common reaction set across the range of temperatures, oxygen concentrations, and sorbent compositions tested. The data are consistent with the basic autoxidation scheme (BAS), the accepted mechanism of autoxidation of aliphatic polymers. We propose a lumped kinetic model to describe the oxidation reaction set and estimate an activation energy of 105 kJ/mol and an oxygen reaction order of 0.5−0.7 from the data accordingly. These parameters can be incorporated into process cycle models to estimate the material lifetime, a critical uncertainty in the deployment of DAC technologies.

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“…1,2 An analysis of the data and additional experiments indicated that all chemical reactions are related to each other. The reactions of the stabilizer lead to color development, [12][13][14][15][16][17] and that of the polymer leads to changes in its molecular structure, which, on the other hand, determine the rheological properties of the granulates 11,18,19 and the mechanical characteristics of the films blown from them. 20,21 However, the general validity of the correlations was in doubt because of the industrial character of the project.…”

Section: Introductionmentioning

confidence: 99%

Two‐step degradation of high‐density polyethylene during multiple extrusion

Epacher

¹

,

Tolvéth

²

,

Stoll³

et al. 1999

J. Appl. Polym. Sci.

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Ensuing our recent studies on polyethylene stabilization, 1,2 further multiple extrusion experiments were carried out with a high-density polyethylene (HDPE) polymer containing various amounts of a sterically hindered phenolic antioxidant. Discoloration, thermoxidative stability, and melt flow index (MFI) retention were measured by standard techniques; the functional group content of the polymer was determined by Fourier transform infrared (FTIR) spectroscopy, and rheological, as well as mechanical properties, were also measured. The results indicated that degradation and stabilization reactions take place according to two different mechanisms in the first and subsequent processing steps, respectively. Color development could be described well by the simple first-order overall reaction kinetics proposed earlier, and color change could be related to the stability of the polymer. The existence of general correlations among the properties proved that all chemical reactions are interrelated. The reactions of the stabilizer lead to color development, while those of the polymer to a modification of its molecular architecture, which determines the rheological and mechanical characteristics of the product.

show abstract

Two-step degradation of high-density polyethylene during multiple extrusion

Epacher

¹

,

Tolvéth²,

Stoll³

et al. 1999

J. Appl. Polym. Sci.

View full text Add to dashboard Cite

Ensuing our recent studies on polyethylene stabilization, 1,2 further multiple extrusion experiments were carried out with a high-density polyethylene (HDPE) polymer containing various amounts of a sterically hindered phenolic antioxidant. Discoloration, thermoxidative stability, and melt flow index (MFI) retention were measured by standard techniques; the functional group content of the polymer was determined by Fourier transform infrared (FTIR) spectroscopy, and rheological, as well as mechanical properties, were also measured. The results indicated that degradation and stabilization reactions take place according to two different mechanisms in the first and subsequent processing steps, respectively. Color development could be described well by the simple first-order overall reaction kinetics proposed earlier, and color change could be related to the stability of the polymer. The existence of general correlations among the properties proved that all chemical reactions are interrelated. The reactions of the stabilizer lead to color development, while those of the polymer to a modification of its molecular architecture, which determines the rheological and mechanical characteristics of the product.

show abstract

Efficiency of processing stabilizers using a micro-oxygen uptake technique

Cited by 10 publications

References 32 publications

Chemical Kinetics of the Autoxidation of Poly(ethylenimine) in CO₂ Sorbents

Chemical Kinetics of the Autoxidation of Poly(ethylenimine) in CO₂ Sorbents

Two‐step degradation of high‐density polyethylene during multiple extrusion

Two-step degradation of high-density polyethylene during multiple extrusion

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Efficiency of processing stabilizers using a micro-oxygen uptake technique

Cited by 10 publications

References 32 publications

Chemical Kinetics of the Autoxidation of Poly(ethylenimine) in CO2 Sorbents

Chemical Kinetics of the Autoxidation of Poly(ethylenimine) in CO2 Sorbents

Two‐step degradation of high‐density polyethylene during multiple extrusion

Two-step degradation of high-density polyethylene during multiple extrusion

Contact Info

Product

Resources

About

Chemical Kinetics of the Autoxidation of Poly(ethylenimine) in CO₂ Sorbents

Chemical Kinetics of the Autoxidation of Poly(ethylenimine) in CO₂ Sorbents