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Paper, print media and biomaterials

LGP2, a center of innovative research
LGP2, a center of innovative research

> Research

Manufacturing stronger paper with fewer raw materials and less energy, without sacrificing quality

Published on June 11, 2015
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To limit the increase in paper production costs, one approach is to reduce the amount of fibers and increase the proportion of inorganic fillers. However, the problem is to maintain the mechanical properties of products with a reduced number of bonds between fibers.

The LGP2, represented by Pierre Dumont, Associate Professor (Grenoble INP), and Raphaël Passas, Research Engineer (Agefpi), took part in the European PowerBonds project (2012-2014) involving 16 academic and industrial partners, supported by the ERA-NET WoodWisdom-Net research programme and funded by the Ministry of Agriculture, Agrifood and Forestry.

The objective of PowerBonds is to cater for the need to improve the properties of fibres and bonds, so as to generate value added for the paper and cardboard industry. Reducing the grammage of paper and cardboard is an enticing prospect, given that it translates into lower raw material, energy and transport costs. However, this reduction is synonymous with greater product fragility, owing to the smaller number of fibres and inter-fibre bonds.

The project's objective? To increase the resistance of both fibres and bonds, by using new characterisation and modelling tools (based on cutting-edge microscopy and mechanical characterisation techniques) and applying new chemical or mechanical modification processes. This fresh knowledge will enable a link to be established between the results obtained at fibre level and the phenomena that occur on a large scale in a sheet of paper. Based on this multi-scale approach, it is possible to optimise the use of raw materials, reduce costs and improve certain properties of paper for specific applications, such as printing, writing or packaging.
The LGP2 lab contributed to three of the six working groups: W2 (characterisation of individual fibres and bonds), W4 (macroscopic characterisation of manufactured papers) and W3 (modelling of fibre networks), which relied on the data produced by the two previous groups.

During the course of the project, LGP2 made considerable advances regarding the characterisation of both individual fibres and fibres within a network. Indeed, it developed a micro-robotic platform to perform compression and bending tests on isolated fibres in a controlled environment (humidity and temperature), as well as a deformation model for fibres during edge compression and bending, devices to perform X-ray microtomography in situ during drying, and a multi-scale model based on a theoretical discrete homogenisation approach allowing the elastic properties of fibre networks to be predicted .

In addition, tools with the capacity to automatically process 3D microtomography images now enable fibres in a network to be labelled individually and the contact area between fibres to be estimated. Lastly, a database was set up to document the microstructural properties of paper according to its manufacturing conditions (forming, pressing and drying), which are obtained by analysing three-dimensional images of different types of paper.

Furthermore, there are a number of areas to explore that will ensure the continuity of the PowerBonds project:
  • Determining interactions between fibres at nanometric level using force spectroscopy.
  • Modelling inverse size exclusion chromatography for a fibre/starch mixture, so as to optimise the use of the experimental results obtained.
  • Continuing the in situ study on the drying and rewetting of individual fibres and fibre networks using X-ray synchrotron imaging.
  • Developing techniques to determine the average orientation angle of microfibrils.

LGP2's full report: Rapport d'activité du LGP2 dans le cadre de PowerBonds

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Date of update June 11, 2015

Université Grenoble Alpes