Fibre composites with natural adhesive

Status

completed

Summary

Motivation

Both environmental legislations and consumer demands have increased the pressure on manufacturers of materials as well as end-products to consider the environmental impact of their products along all stages of their life cycle, from raw material extraction to waste management. As a part of the "cradle-to-grave", furthermore of the "cradle-to-cradle" approaches, composite materials based on renewable resources have gained considerable interest from the industries. Those environmentally-friendly and low-cost bio-composites such as natural fibres can replace conventional materials such as glass fibres and synthetic plastics.

In general synthetic thermoplastics such as Polypropylene and Polyethylene are applied as a binder to generate mouldable non-woven materials. Due to the use of fossil fuel-based thermoplastics the composites are not biodegradable. In order to overcome this limit the material developed in this project (called "NFC" Natural Fibre Composite) consists exclusively of residues from renewable resources and biodegradable polymers.

Project goals and contents

As application fields for this material, wall panels and mouldable bio-composites (e.g. packaging) were demonstrated. The aim was to develop prototypes for these application opportunities and to verify them.

This project aims to answer the following questions:

• What is the ideal mixture of raw materials?
• What conditions are needed for the applications?
• Which process parameters allow a constant quality in the non-woven production?
• How can the customer demands on wall panels be satisfied with the non-woven material?
• What kinds of moulded packaging can be created and how do they have to be designed?
• Do the prototypes meet the technical and legal regulations?

Contents

Fibre composites with natural adhesive

The fibres used for the compound were mainly natural residues like flax combings and straw. Straw is a cheap and easy-to-get raw material. However, it has to be conditioned to fit the non-woven production process. To embed the heavy straw fibres in the non-woven mat, the use of flax fibres was essential. The decomposition of the wax layer was used to reach an optimal adhesion level with the starch-based binders. Several biopolymers were tried as comparative binders such as Polylactide (PLA), PHB and starch. They were used as flakes and powder and tested in different processes.

Choosing capable processing procedures

With the selected binders and fibres several techniques to insert the binder in the fibre structure were tested. The best results were achieved by using the sheet-forming process and PLA fibres due to their high resistance.

By adjusting process parameters, both low and high density of the non-woven can be realised. Subsequently the result is applicable for both, the wall panels and the moulded packaging.

Using the sheet-forming process and starch-based binders, prototypes were produced which reached similar resistance and weight as wood fibreboards. Very lightweight and inherently stable prototypes were also produced with a mixing process of straw and starch-based binders. Problems arose only when trying to increase the dimensions of the boards to a large extent.

As noted above, the best results were achieved when using the sheet-forming process and the PLA fibre as a binder. Therefore the further experiments were continued with this process and raw materials.

Results

Wall panels

The non-woven was compressed to reach the desired weight and resistance with a discontinuous moulding press. A multilayer construction for the wall panels was designed to fulfil all of the objectives including the low specific weight, mechanical strength and easy handling.

Several surface treatment methods were demonstrated, and the product does not require any additional work for fitting at the construction site. To achieve a proper sound insulation whilst keeping the low specific weight the outer layers were more compressed than the inner ones. To be used as a wall panel, the product should have a hard and smooth surface. This was realised through high temperature and pressure in the moulding press. In a one-step process a lamination is also viable without any additional binder. With this character, a number of alternative applications are feasible. The panels meet legal and customer demands regarding fire protection and acoustic insulation.

Packaging

The non-woven material can be used to produce mouldable packaging but it is not the first choice product to launch due to its low added value and cheap competing products. The same production process can be used to produce more significant applications as the experiments and tests have shown.

Nevertheless the use of the non-woven material without any further mechanical processing (compression-mould) can bring a higher profitability. It is applicable as a protective and decorative packaging substance and shows better chances to penetrate the market.

Although the material shows promising performance to be used as a packaging material, it can be introduced to the market through more sophisticated products (e.g. suitcases). Accordingly, the higher added value and a better image can be created.

Project management

GrAT - Gruppe zur Förderung der Angepassten Technologie
Dr. Robert Wimmer

Team Gruppe Angepasste Technologie:
Mag. (FH) Rudolf Bintinger, Dr. Manfred Drack

Project or cooperation partner

• WK Naturfaser Technologie GmbH & Co KG
  Dkfm. Wolfgang Karner, Josef Riedl
• Trennwandsysteme Scheicher, Alois Scheicher GmbH
  Rudolf Michael Scheicher
• Zuckerforschung Tulln GmbH
  Dr. Martin Kozich, Dr. Karl-Jürgen Mann, Dr. Marnik Michel Wastyn
• Höfer Ges.m.b.H & Co.KG.
  Wolfgang G. Höfer, Robert Hamedinger
• FEX ÖKO-Faserverarbeitungs-GmbH
  Ing. Johann Payerl
• Verpackungszentrum Graz
  Helmut Meininger, Bettin Reichl
• FH Salzburg, Studiengang Design & Produktmanagement
  Mag. Günther Grall, Dr. Bernhard Rothbucher
• PE Design, Delft
  DI Paul Eilbracht
• Spezialmaschinen Dr. Otto Angleitner Ges.m.b.H & Co.KG.
  DI Helmut Angleitner
• FH Salzburg, Holzwerkstoffe, DI Dr. Olaf Treusch
• R+S Technik GmbH, Ernst Spengler, Dirk Fischer
• SFK Tischler GmbH, Gerhard Spitzbart
• TU Wien, Institut für Werkstoffwissenschaft und Werkstofftechnologie, Nichtmetallische Werkstoffe, DI Dr. Vasiliki-Maria Archodoulaki
• TU Wien, Institut für Hochbau und Technologie, Zentrum für Baustoffforschung, Werkstofftechnik und Brandschutz, DI Dr. Heinrich Bruckner
• Technoboard Engineering GmbH, Werner Lokaj

GrAT - Gruppe zur Förderung der Angepassten Technologie
Dr. Robert Wimmer
Wiedner Haupstraße 8-10, 1040 Wien
Tel.: +43 1 58801 49523
Fax: +43 1 58801 49533
E-Mail: rw@grat.at