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3D-shapeable thermoplastic paper materials
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.), Solid Mechanics (Div.).ORCID iD: 0000-0001-8699-7910
2013 (English)In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, Vol. 28, no 4, 602-610 p.Article in journal (Refereed) Published
Abstract [en]

The purpose of this work was to investigate to what extent it is possible to improve the thermoplastic properties of paper materials so that 3D-shapeable paper products can be manufactured. For that purpose, the addition of various chemical adjuvants, known to improve both tensile strength index and strain at break, was investigated. Adding polylactide latex was found to significantly improve both the tensile strength properties and strain at break of paper materials. To enhance their strainability, the paper sheets were cured at an elevated temperature of 150 degrees C. The improved strainability after curing is hypothesized to relate to the spreading of the polylactide latex (minimum film-forming temperature of 90 degrees C) on the fibre surfaces, improving the relative bonded area. Both the tensile strength index and strain at break improved significantly with no densification of the paper sheets. A second aim was to make double-curved board structures in a hydroforming equipment, using the sheets treated with polylactide latex under various conditions. Double-curved sheets with a nominal strain at break of over 20% could be formed by adding 20% polylactide latex. Hydroforming had to be done at temperatures exceeding the minimum film-forming temperature of the polylactide latex to significantly improve the strain at break during the forming operation.

Place, publisher, year, edition, pages
2013. Vol. 28, no 4, 602-610 p.
Keyword [en]
Deep-drawing, Hydroforming, Thermoplastic board, Polylactide latex, Bleached kraft pulp, Three-dimensional packaging materials, Tensile index, Strain at break
National Category
Paper, Pulp and Fiber Technology
URN: urn:nbn:se:kth:diva-140183DOI: 10.3183/NPPRJ-2013-28-04-p602-610ISI: 000328642400016ScopusID: 2-s2.0-84891841593OAI: diva2:688653

QC 20140117

Available from: 2014-01-17 Created: 2014-01-17 Last updated: 2014-11-07Bibliographically approved
In thesis
1. Preparation and characterization of nanoporous cellulose fibres and their use in new material concepts
Open this publication in new window or tab >>Preparation and characterization of nanoporous cellulose fibres and their use in new material concepts
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The overall objective of the work in this thesis is to better utilize the non-collapsed structure of the delignified wood-fibre cell wall in the preparation of new types of materials.

In order to utilize the fibres in new materials, it is crucial to have a well-defined starting material and to know how it reacts to certain treatments of the fibres. A new robust method for measuring the average pore size of water-swollen fibres-rich in cellulose is presented. This method is based on solid-state NMR, which measures the specific surface area [m2/g] of water-swollen samples, and the fibre saturation point (FSP) method, which measures the pore volume [water mass/solid mass] of a water swollen sample. These results can be combined since they are both recorded on water-swollen fibres in the presence of excess water and neither is based on any assumption of any particular pore geometry. Delignifed wood fibres (chemical pulp fibres) have an open fibrillar structure, with approximately 20 nm thick fibril aggregates arranged in a porous structure with a specific surface area of 150 m2/g. This open structure was preserved in the dry state by a liquid-exchange procedure followed by careful drying in argon gas. The dry structure had a specific surface area of 130 m2/g, which implies that the porous structure was preserved in the dry state.

New fibre-basedmaterials were prepared by two different strategies.

The first strategy was to utilize the open nanoporous fibre wall structure for the preparation of nanocomposites. The nanoporous structure was used as a scaffold, allowing monomers to impregnate the structure and to be in-situ polymerized inside the fibre wall pores. Poly(methyl methacrylate) (PMMA) and poly(butylacrylate) (PBA) were synthesized inside the dry nanoporous fibre wall structure, and an epoxy resin was cured in never-dried fibres oxidized to different degrees by TEMPO. The composites prepared thus have a mixture of fibril aggregates and a polymer matrix inside the fibre wall. The structure and performance of the composite materials were evaluated both by high resolution microscopy and mechanically. Characterization of the composite showed that the polymer matrix was successfully formed inside the fibre wall pores. The structural changes caused by oxidation were preserved and utilized for the composite with the epoxy matrix. By tailoring the supramolecular structure of fibres in their water-swollen state, it was hence indeed possible to control the mechanical performance of the nanostructured fibre composites.

The secondbstrategy used to prepare composites was to improve the thermoplastic properties of paper by adding polylactic acid (PLA) latex during the preparation of fibrebsheets. By the addition of PLA-latex, it was possible to form double curved sheets with a nominal strain at break of 21%.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. 57 p.
TRITA-CHE-Report, ISSN 1654-1081 ; 2014:41
National Category
Paper, Pulp and Fiber Technology Composite Science and Engineering
Research subject
Fibre and Polymer Science
urn:nbn:se:kth:diva-155530 (URN)978-91-7595-290-1 (ISBN)
Public defence
2014-11-28, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Knut and Alice Wallenberg Foundation

QC 20141107

Available from: 2014-11-07 Created: 2014-11-06 Last updated: 2014-11-07Bibliographically approved

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