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Characterization of Reduced and Surface-modified Graphene Oxide in EBA Composites for Electrical Applications
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. (Coating Technology Division)
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(English)Manuscript (preprint) (Other academic)
National Category
Engineering and Technology
Research subject
Fibre and Polymer Science
Identifiers
URN: urn:nbn:se:kth:diva-226884OAI: oai:DiVA.org:kth-226884DiVA, id: diva2:1201780
Note

QC 20180427

Available from: 2018-04-26 Created: 2018-04-26 Last updated: 2018-04-27Bibliographically approved
In thesis
1. Inorganic and organic polymer-grafted nanoparticles: their nanocomposites and characterization
Open this publication in new window or tab >>Inorganic and organic polymer-grafted nanoparticles: their nanocomposites and characterization
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Nanocomposites (NCs) have been widely studied in the past decades due to the promising properties that nanoparticles (NPs) offer to a polymer matrix, such as increased thermal stability and non-linear electrical resistivity. It has also been shown that the interphase between the two components is the key to achieving the desired improvements. In addition, polymer matrices are often hydrophobic while NPs are generally hydrophilic, leading to NP aggregation. To overcome these challenges, NPs can be surface-modified by adding specific molecules and polymers. In the present work, a range of organic and inorganic NPs have been surface-modified with polymers synthesized by atom transfer radical polymerization (ATRP) or surface-initiated ATRP (SI-ATRP).Cellulose nanofibrils (CNF) and cellulose nanocrystals (CNC) are highly crystalline NPs that can potentially increase the Young’s modulus of the NC. In this study, a matrix-free NC was prepared by physisorption of a block-copolymer containing a positively charged (quaternized poly(2-(dimethylamino)ethyl methacrylate), qPDMAEMA) and a thermo-responsive (poly di(ethylene glycol) methyl ether methacrylate, PDEGMA). The modified CNF exhibited a thermo-responsive, reversible behavior. CNCs were polymer-modified either via SI-ATRP or physisorbed with poly (butyl methacrylate) (PBMA) to improve the dispersion and interphase between them and a polycaprolactone (PCL) matrix during extrusion. The mechanical properties of the NCs containing CNC modified via SI-ATRP were superior to the reference and unmodified materials, even at a high relative humidity.Reduced graphene oxide (rGO) and aluminum oxide (Al2O3) are interesting for electrical and electronic applications. However, the matrices used for these applications, such as poly(ethylene-co-butyl acrylate) (EBA) and low density polyethylene (LDPE) are mainly hydrophobic, while the NPs are hydrophilic. rGO was modified via SI-ATRP using different chain lengths of PBMA and subsequently mixed with an EBA matrix. Al2O3 was modified with two lengths of poly(lauryl methacrylate) (PLMA), and added to LDPE prior to extrusion. Agglomeration and dispersion of the NCs were dependent on the lengths and miscibilities of the grafted polymers and the matrices. rGO-EBA NCs showed non-linear direct current (DC) resistivity upon modification, as the NP dispersion improved with increasing PBMA length. Al2O3-LDPE systems improved the mechanical properties of the NCs when low amounts of NPs (0.5 to 1 wt%) were added, while decreasing power dissipation on the material.Finally, PLMA-grafted NPs with high polymer quantities and two grafting densities in Al2O3 and silicon oxide (SiO2) nanoparticles were synthesized by de-attaching some of the silane groups from the surfaces, either by hydrolysis or by a mild tetrabutylammonium fluoride (TBAF) cleavage. These compounds were characterized and compared to the bulk PLMA, and were found to have very interesting thermal properties.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2018. p. 71
Series
TRITA-CBH-FOU ; 2018:15
Keyword
Si-ATRP, ATRP, polyelectrolytes, rGO, aluminium oxide, silica, CNF, CNC, PCL, LDPE, EBA, nanocomposites, matrix-free, extrusion
National Category
Polymer Technologies
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-226888 (URN)978-91-7729-752-9 (ISBN)
Public defence
2018-05-25, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20180427

Available from: 2018-04-27 Created: 2018-04-26 Last updated: 2018-04-27Bibliographically approved

Open Access in DiVA

The full text will be freely available from 2020-04-24 14:13
Available from 2020-04-24 14:13

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