FAIR-CT98-3919 New functional biopolymer - natural fibre - composites from agricultural resources

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Biocomposites/Boards : Biopolymers/Gums : Composts/Fertilisers : FAIR Area 1.2 - Green Chemicals and Polymers Chain : Fibre : Paints/Coatings/Plastics

	Contract No:	FAIR-CT97-3919
	Date Prepared:	July 2001
	Source:	Final Report Abstract and Scientific Synthesis

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Final Report Scientific Synthesis

Final Report Abstract

Source: Progress Report June 2000

Consortium: The project was co-ordinated by Fraunhofer Gesellschaft zur Förderung der angewandten Forschung e.V., Munchen (Germany) and is now co-ordinated by the Institut for Verfahrenstechnik und Verpackung, Freising (Germany), in partnership with Eidgenötsische Technische Hochschule Zurich, (Switzerland), Universita' degli Studi di Bologna, Dipartimento di Chimica G Ciamician, Bologna (Italy), Organic Waste Systems NV, Gent (Belgium),Vakgroep Biochemie, Fysiologie en Microbiologie, Universiteit Gent, (Belgium), Centro Ricerche FIAT , Orbassano (Italy)

Abstract

Objectives The project has the following objectives:

• Selection of suitable fibre and matrix components based on agro-industrial resources.
• Providing chemically modified matrix materials from renewable resources.
• Optimising processing methods for the new biocomposites.
• Manufacturing demonstration parts on a pre-competitive level, with the automotive industry the main potential market.
• Characterising the new materials according to industrial standards.
• Assessing bio-stability and biodegradability of the composites
• Manufacturing parts where there is a specific need for biodegradability.
• Establishing a cradle to grave analysis with respect to the environmental and economic impacts of the processed demonstration parts.

Activities The activities are divided into four tasks as follows;

Task 1 Natural fibres

• procurement of raw materials (hemp, flax, miscanthus, sorghum, broom, etc)
• separation, degumming
• fibrillation
• fibre fractionation
• material manufacturing
• yarn production
• textile processing
• surface modification

Task 2 Matrix materials

• procurement of PHF, PHBV, TPS/PCL, PLA
• additives, colours, fillers
• chemical modification
• reactive extrusion

Task 3 Processing of biocomposites

A. Compounding/extrusion

• short fibre reinforced injection mouldable mass
• assessment of rheological data
• reactive extrusion
• extrusion coating

B. Injection moulding

• low - high fibre content
• variation of fibre length

C. Continuous fibre reinforced composites

• textile precursors (knitting, weaving)
• impregnation process
• hot pressing (sheet moulding)
• extrusion coating

Task 4 Demonstration parts

• automobile use (car parts)
• containers, cans
• funeral articles
• extruded profiles
• earth anchors, geotextiles

The matrix materials selected from renewable resources were Polylactic Acid (PLA, semi- commercial grade), blends of native starch with other polymers (in three commercial grades), starch derivatives (larger scale experimental products), and proteins (at the pure experimental scale). PLA and starch derivatives had to be plasticised to obtain a good matching of the mechanical properties between fibres and matrices. Proteins still can not be processed using regular thermoplastic conversion.

The natural fibre sources selected were flax, broom, hemp and grass. These were subject to physical treatments, mechanical decortication and steam explosion. Chemical modifications tested were etherification and esterification. Regenerated Cellulose fibres were used as reference.

For the production of injection moulded parts, matrix and fibres have first to run through a compounding step to achieve fibre containing granules. For this step, feeding of fibre into the extruder is a significant technical problem. Feeding with fibres in compacted form (card, sliver) gave good results for one partner. An alternative approach was developed within the project. This method, that fed the fibres in single form, was found to be rate limiting giving too low a rate of delivery.

Injection moulding was carried out in three stages:

• Mini-moulding of small test bars (an efficient way to work with small amounts of materials
• Moulding of regular test bars, and
• Moulding of four different test products.

Fibre reinforced injection moulded composites were mainly made in combination with PLA and 10% to 40% of non-modified or several types of chemically modified flax fibres. For compression moulding, hybrid fleeces from natural (flax) and polymeric (PLA) fibres were made, with weight fractions of the natural fibres between 30% and 65%.

The resulting compression moulded parts were flat sheets and one type of an automotive test product.

The biodegradation tests in soil showed a complete biodegradability of natural polymers and fibres. PLA shows only a very slow degradation under these conditions, whether or not in combination with fibres.

Under controlled composting conditions, natural fibres and PLA are completely degradable.

For two alternative starch blends and chemically modified starch, degradation was much slower or even not detectable.

State of progress In the second project period, delays had to be faced due to the following reasons:

• Problems in preparing polymeric matrix materials from natural resources.
• Problems in achieving achieve good compounding results with fibres, leading to shortage of enough fibre reinforced material for further injection moulding trials.

However, the problems have been solved and the project plan has been changed accordingly. No significant deficits are anticipated as the project moves towards completion..

Achievements The use of fibre reinforcement in injection moulding led to tensile properties that are only slightly better than pure PLA. Better relative improvement could be achieved on matrices of lower tensile strength than PLA. The longer fibre length that could be used in compression moulding enabled a significant increase of tensile properties over the matrix material.

First demonstration parts were made, some of them ahead of the project plan. Characterisation and biodegradation measurements are ongoing according the needs of the project. The basic structure for the LCA work has been set up.

Future actions The main aims of the future activities are as follows:

• Scale up of production of modified starch to the 50 kg scale.
• Scale-up of compounding with fibres to the 50 kg scale.
• Experimental production of different demonstration parts in larger scale.
• carry out life cycle and economic analysis.