Diffusion of antioxidants in sheets and plates of isotactic polypropylene measured by isothermal differential-thermal-analysis

Schwarz, T.; Steiner, G.; Koppelmann, J.

doi:10.1007/bf01904450

Cited by 9 publications

(1 citation statement)

References 17 publications

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“…The variation of S O2 now enables to simulate the whole range of induction times compiled from the literature under 0.1 MPa and 0.02 MPa, except the lowest values attributed to polypropylenes which are atactic, preoxidized or with a high catalyst residues amount (Figure ). The slope of the Arrhenius graph, i.e.…”

Section: Discussion: Towards a “Universal” Kinetic Modelmentioning

confidence: 99%

Impact of oxygen transport properties on polypropylene thermal oxidation, part 1: Effect of oxygen solubility

François-Heude

Richaud

Guinault

et al. 2014

J of Applied Polymer Sci

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A general kinetic model is proposed to describe the polypropylene thermal oxidation of thin polypropylene films in a wide range of temperatures (from 60 to 200 C) and oxygen partial pressures (from 0.02 to 5 MPa) using a single set of parameters.This model was calibrated with several series of experimental data including analyses of primary (hydroperoxides) and secondary oxidation products (carbonyl species), and subsequent changes in macromolecular properties (average molecular masses). It predicts the experimental data previously published in the literature in terms of induction times and maximal oxidation rates. The variability of the oxygen solubility coefficient allows to explain the scattering of induction times and oxidation rates among the whole iPP family, but also the dependence of this latter quantity with oxygen partial pressure. This variability is presumably due to iPP polymorphism in the temperature range where oxygen permeability is commonly measured. It is concluded that the kinetic model can be used to study the direct effect of iPP morphology on its thermal oxidation kinetics (chemistry of oxidation).

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Section: Discussion: Towards a “Universal” Kinetic Modelmentioning

confidence: 99%

Impact of oxygen transport properties on polypropylene thermal oxidation, part 1: Effect of oxygen solubility

François-Heude

Richaud

Guinault

et al. 2014

J of Applied Polymer Sci

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Migration and blooming of stabilizing antioxidants in polypropylene

Spatafore¹,

Pearson²

1991

Polymer Engineering & Sci

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We have studied the migration of the hindered phenol, octadecyl‐3,5‐bis (1,1‐dimethylethyl)‐4‐hydroxybenzenepropanoate, and the phosphite co‐stabilizer tris 2,4‐bis(1,1‐dimethylethyl)phenylphosphite, out of films of polypropylene (nominal melt flow 3.5 g/10 min). Loss of additive from an initial 10% weight‐% level in the polymer was followed by FTIR bands in the appropriate regions. Temperatures of 298 K, 313 K and 333 K were used. An attempt was made to analyze migration data using Fick's law for diffusion by means of a least squares fit. Octadecyl‐3,5‐bis (1.1‐dim ethylethyl)‐4‐hydroxybenzenepropanoate diffused according to Fick's law with a temperature independent diffusion constant (D = 1.27 × 10−15 m2 S−1) to a steady state concentration of 7.2 % + −0.56 weight‐%. The phosphite did not diffuse at all at 298 K and 313 K, but diffused with D = 8.1 × 10−16 m2 S−1 to a steady level at 333 K. Our interpretation of the phosphite migration data assumes that most of the phosphite in the sample is immobilized. A subset of the total phosphite level is free to diffuse to the surface of the polymer.

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Long‐term properties of hot‐water polyolefin pipes—a review

Gedde

Viebke

Leijström

et al. 1994

Polymer Engineering & Sci

181

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This is a review on the long‐term behavior of polyolefin pipes used in hot‐water environments. Included in the review is work done on pipes of crosslinked polyethylene, isotactic poly(butene‐1), isotactic polypropylene and medium‐density polyethylene, and in particular the extensive work performed at Studsvik, Sweden. A collective view of the changes in antioxidant concentration profiles and molecular/physical structure accompanying hot‐water exposure is presented. Failure at high stress levels is preceded by gross deformation (Stage I failure), whereas at lower stresses fracture is brittle either without any signs of thermal oxidation (Stage II) or induced by a strong and spatially concentrated thermal oxidation (Stage III). It is shown that the Stage III lifetime can be divided into three phases, denoted Regimes A, B, and C. They involve internal precipitation of antioxidant from a supersaturated solution (Regime A), diffusion‐controlled migration of antioxidant to the surrounding media (Regime B), and degradation of the polymer by thermal oxidation (Regime C). For hitherto reported cases the Regime B life constitutes 80% to 90% of the entire life. A presentation is also made of current lifetime extrapolation methods.

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Diffusion of antioxidants in sheets and plates of isotactic polypropylene measured by isothermal differential-thermal-analysis

Cited by 9 publications

References 17 publications

Impact of oxygen transport properties on polypropylene thermal oxidation, part 1: Effect of oxygen solubility

Impact of oxygen transport properties on polypropylene thermal oxidation, part 1: Effect of oxygen solubility

Migration and blooming of stabilizing antioxidants in polypropylene

Long‐term properties of hot‐water polyolefin pipes—a review

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