Fundamentals on the development of ecological high class insulation composites made from natural plant fibres

Fundamentals on an insulation made from flax and hemp fibres which can be directly pargeted on the outer wall of a building had been developed. Only ecological glues and additives were used. Variations of the produc­tion and the additives optimized the technical properties. In addition flame proofing and thermal transfer were tested. After the laboratory tests a prototype finished the project.

Short Description




Starting point/Motivation

Currently, commercially available insulation materials are primarily restricted to in-house utilisation. Furthermore, most insulation materials still contain toxicological and eco-toxicological constituents as organic halogen compounds and the most widely used boric compounds. The mechanical properties of current insulation boards are too low to facilitate outdoor use.

Contents and Objectives

The task of this project is to determine the basic principles and industrial possibilities for manufacturing an insulation board for outside use, which is composed of natural fibers.

The activities include substitution of boric compounds, increasing the transverse tensile strength and development of a hydrophobic coating. Key aspects of this study are the compliance of sustainability, the increase in energy efficiency and the total abandonment of toxicological and eco-toxicological constituents in favor of natural alternatives.


A rapid test method was developed using papers as well as fiber boards to assess the adhesive power and fire protecting potential of the designed pastes and surfactants. Due to substantial technical problems in the pilot plant and inability to simulate the production process, all of the carding trials had to be performed using the production plant.

To enhance the transversal tensile strength, different parameters of the needling process as for example type and number of needles and intensity of penetration were varied and evaluated. Further methods included chemical analyses, flammability tests, measurements of the transversal tensile strength, determination of thermal conductivity and resistance tests to certain mildew species.


Subsequent applied needling increased the transversal tensile strength forty fold while reducing the thickness of the insulation boards by 60%. In consequence the heat transfer resistance was reduced analogically while the thermal conductivity was nearly maintained. The latter was not influenced by increasing moisture in the insulation boards as well.

The assortment of ecologically harmless flame retardants was constricted due to the required processability on the production plant and maintenance of the adhesive power of the starch pastes. Silicates increased the adhesive power of the glue. However the fire protection was too low. Ammonium- polyphosphate decreased the stiffness of the insulation boards compared to the borate- starch and silicate- starch glues.

In sufficient concentration these environmentally harmless compounds provided satisfying fire protection to the insulation boards. The trials performed on the production plant revealed an incredible loss of glue up to 50%, which demonstrates the possibilities to increase the economic performance of the current production.

Prospects / Suggestions for future research

Despite numerous technical challenges, the development of an ecologically and technically valuable insulation board consisting of over 95% renewable resources succeeded. The production of this product is currently not realisable because of economic issues.

Further optimisations in the production plant are required to improve the loss of raw material during the wet carding process. Practical tests should be carried out to assess the required ratio of transverse tensile stress and fiber consumption. The performance of the developed insulation board in outside use needs to be evaluated.

Project Partners

Project management

University of Natural Resources - IFA-Tulln,
Institute for Natural Materials Technology
Ass. Prof. Dr. Norbert Mundigler

Project or cooperation partners

Contact Address

University of Natural Resources and Life Sciences, Vienna
Department for Agrobiotechnology, IFA-Tulln
Institute for Natural Materials Technology
Ass.Prof. Dr. Norbert Mundigler
Konrad-Lorenz-Strasse 20
3430 Tulln
Tel.: +43 (2272) 66280-301
Fax: +43 (2272) 66280-303