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Antioxidant activity in aluminium oxide - Poly(ethylene-co-butyl acrylate) nanocomposites
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
2012 (English)In: Polymer degradation and stability, ISSN 0141-3910, E-ISSN 1873-2321, Vol. 97, no 6, 1017-1025 p.Article in journal (Refereed) Published
Abstract [en]

The antioxidant activity of Irganox 1010 (0.2 wt%) in aluminium oxide (2-12 wt%) - poly(ethylene-co-butyl acrylate) nanocomposites was studied. The aluminium oxide nanoparticles were in three different forms: uncoated and coated with either octyltriethoxysilane or aminopropyltriethoxysilane. The activity of the stabilizer in the nanocomposites was assessed by determining the oxidation induction time (OIT) using DSC. Composites with untreated aluminium oxide nanoparticles showed a much shorter OIT than the pristine polymer with the same overall antioxidant concentration indicating adsorption of the antioxidant onto the nanoparticle surfaces. The adsorption of antioxidant onto both uncoated and coated nanoparticles was confirmed by X-ray photoelectron spectroscopy. Composites containing coated nanoparticle fillers showed a significantly smaller depression of the OIT, indicating that the replacement of hydroxyl groups with organic silane tails decreased the concentration of available adsorption sites on the particle surfaces. Composites with a filler coated with a silane having terminal aliphatic amine groups showed an increased OIT with respect to that of the pristine polymer suggesting a synergistic on the stability effect between the antioxidant and the amine groups. The long-term activity of the stabilizer was assessed by measuring the OIT on samples after ageing in air at 90°C for 720 h. The decrease in OIT with increasing ageing time of the nanocomposites was slower than for the unfilled polymer. A possible interpretation of these data is that the antioxidant was slowly released from the adsorption sites on extended ageing.

Place, publisher, year, edition, pages
2012. Vol. 97, no 6, 1017-1025 p.
Keyword [en]
Aluminium oxide, Antioxidant, Irganox 1010, Nanocomposites, Poly(ethylene-co-butyl acrylate)
National Category
Polymer Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-96187DOI: 10.1016/j.polymdegradstab.2012.03.012ISI: 000304641300025Scopus ID: 2-s2.0-84860385648OAI: oai:DiVA.org:kth-96187DiVA: diva2:529857
Funder
Swedish Research Council, 621-2007-5095
Note

QC 20120531

Available from: 2012-05-31 Created: 2012-05-31 Last updated: 2017-12-07Bibliographically approved
In thesis
1. Preparation and long-term performance of poly(ethylene-co-butyl acrylate) nanocomposites and polyethylene
Open this publication in new window or tab >>Preparation and long-term performance of poly(ethylene-co-butyl acrylate) nanocomposites and polyethylene
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The current study discusses the preparation and long-term performance of polymer composites used for various purposes under different ageing conditions.

The first part deals with the preparation and characterization of polymer nanocomposites based on poly(ethylene-co-butyl acrylate) (EBA–13 and EBA–28 with 13 and 28 wt % butyl acrylate, respectively) and 2–12 wt % (0.5–3 vol %) of aluminum oxide nanoparticles (two types with different specific surface areas and different hydroxyl-group concentrations; uncoated and coated with, respectively, octyltriethoxysilane and aminopropyltriethoxysilane). The nanocomposite with EBA–13 showed better overall nanoparticle dispersion while EBA–28 resulted in poor dispersion, probably due to insufficiently high shear forces acting during extrusion mixing which were unable to break down nanoparticle agglomerates.

The activity of hindered phenolic antioxidant (0.2 wt%) in all EBA nanocomposites was assessed by determining the oxidation induction time using DSC. The composites containing uncoated aluminium oxide nanoparticles showed a much shorter initial OIT than the pristine polymer with the same initial concentration of antioxidant, indicating adsorption of antioxidant onto the nanoparticle surfaces. Composites containing coated nanoparticles showed a significantly smaller decrease in the initial OIT, suggesting the replacement of hydroxyl groups with organic silane tails, decreasing the concentration of available adsorption sites on the nanoparticle surfaces. The decrease in OIT with increasing ageing time in dry air at 90 °C of the nanocomposites was slower than

that of the unfilled pristine polymer, suggesting a slow release of antioxidant from adsorption sites.

The EBA nanocomposites exposed to liquid water at 90°C showed faster decrease of OIT than samples exposed to dry or humid air. The migration rate of antioxidant was controlled by the boundary conditions in the case of ageing in humid air and liquid water. The antioxidant diffusivity was lower for the composites containing uncoated ND than for the composites containing ND coated with octyltriethoxysilane or aminopropyltriethoxysilane.

The migration and chemical consumption of deltamethrin DM, (synthetic pyrethroid) and synergist piperonyl butoxide from molded polyethylene sheets was also studied. Deltamethrin and piperonyl butoxide are often used for food  storage and insect control purposes. DM showed no signs of crystallization and remained in a liquid state after being cooled to room temperature. Exposure of polyethylene compound sheets to liquid water (at 80 & 95 °C), caused degradation and hydrolysis of the ester bond in the DM, present in the prepared material, and generated species containing hydroxyl groups. Liquid chromatography and infrared spectroscopy showed a significant migration of the active species in liquid water, whereas in air at 80 °C (60 and 80 %RH) the loss of DM and PBO was negligible over 30 days.

The long-term performance of medium-density polyethylene stabilized with six different phenolic antioxidants (0.1 wt%) in aqueous chlorinated media at 70 °C was studied. The results were compared with data for previously studied solutions of antioxidants in squalane (a liquid, low molar mass analogue of polyethylene). A linear relationship was established between the time to reach antioxidant depletion in polyethylene tape samples and the time in squalane samples. Infrared spectroscopy and scanning electron microscopy of drawn samples revealed the onset of surface oxidation and surface embrittlement in tape samples exposed beyond the time for antioxidant depletion.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. 57 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2012:44
Keyword
Polymer nanocomposite, nanoparticles, aluminium oxide, poly(ethylene-co-butyl acrylate), long-term performance, ageing, antioxidant, OIT, aqueous media, silanization, irganox 1010, deltamethrin, piperonyl butoxide, chlorine dioxide, migration of stabilizer
National Category
Polymer Technologies
Research subject
SRA - Production
Identifiers
urn:nbn:se:kth:diva-104685 (URN)978-91-7501-491-3 (ISBN)
Public defence
2012-11-30, Entreplan (F3), Lindstedtsvägen 26, KTH, Stockholm, 13:00 (English)
Opponent
Supervisors
Projects
Cable insulation materialsLoss of deltamethrin and pipronyl butoxide from polyethylenelong-term performance of polyethylene in chlorine dioxide water
Funder
Swedish Research CouncilXPRES - Initiative for excellence in production research
Note

QC 20121109

Available from: 2012-11-09 Created: 2012-11-09 Last updated: 2013-04-19Bibliographically approved

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