title: Micromechanics of ultra-toughened electrospun PMMA/PEO fibres as revealed by in-situ tensile testing in an electron microscope.
abstract: A missing cornerstone in the development of tough micro/nano fibre systems is an understanding of the fibre failure mechanisms, which stems from the limitation in observing the fracture of objects with dimensions one hundredth of the width of a hair strand. Tensile testing in the electron microscope is herein adopted to reveal the fracture behaviour of a novel type of toughened electrospun poly(methyl methacrylate)/poly(ethylene oxide) fibre mats for biomedical applications. These fibres showed a toughness more than two orders of magnitude greater than that of pristine PMMA fibres. The in-situ microscopy revealed that the toughness were not only dependent on the initial molecular alignment after spinning, but also on the polymer formulation that could promote further molecular orientation during the formation of micro/nano-necking. The true fibre strength was greater than 150 MPa, which was considerably higher than that of the unmodified PMMA (17 MPa). This necking phenomenon was prohibited by high aspect ratio cellulose nanocrystal fillers in the ultra-tough fibres, leading to a decrease in toughness by more than one order of magnitude. The reported necking mechanism may have broad implications also within more traditional melt-spinning research.
authors.affiliation: KTH Royal Institute of Technology, School of Chemical Science and Engineering, Fibre and Polymer Technology, SE-100 44 Stockholm, Sweden.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Andersson
authors.affiliation: KTH Royal Institute of Technology, Department of Materials Science and Engineering, SE-100 44 Stockholm, Sweden.
authors.forename: Valter
authors.initials: V
authors.lastname: Ström
authors.affiliation: KTH Royal Institute of Technology, School of Chemical Science and Engineering, Fibre and Polymer Technology, SE-100 44 Stockholm, Sweden.
authors.forename: Ulf W
authors.initials: UW
authors.lastname: Gedde
authors.affiliation: Department of Chemistry and Polymer Science, University of Stellenbosch, Private Bag X1, Matieland ZA-7602, South Africa.
authors.forename: Peter E
authors.initials: PE
authors.lastname: Mallon
authors.affiliation: KTH Royal Institute of Technology, School of Chemical Science and Engineering, Fibre and Polymer Technology, SE-100 44 Stockholm, Sweden.
authors.forename: Mikael S
authors.initials: MS
authors.lastname: Hedenqvist
authors.affiliation: KTH Royal Institute of Technology, School of Chemical Science and Engineering, Fibre and Polymer Technology, SE-100 44 Stockholm, Sweden.
authors.forename: Richard T
authors.initials: RT
authors.lastname: Olsson