Techniques de mise en forme de nouveaux matériaux biofragmentables

Propriétés physiques comparées de mélanges d’amidon de blé et d’acétate de cellulose et de mélanges d’amidon de blé et d’acétate d’amidon

Processes for making new biofragmentable materials

Compared physical properties of wheat starch and cellulose acetate blends and of wheat starch and starch acetate blends

¹ Ingénieur INSA Lyon, Ingénieur EAHP Strasbourg. Institut de Formation Technique Supérieure de Charleville Mézières (IFTS).
² Assistants d’ingénieurs (IFTS).
³ Professeur de Chimie Industrielle, Directeur de l’Ecole Supérieure d’ingénieurs en Emballage et Conditionnement de Reims (ESIEC).

Abstract

Biofragmentable pellets were obtained by extrusion using dry blends based on :

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  wheat starch and cellulose acetate which substitution degree (SD) was close to 2.3, on the one hand,

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  wheat starch and starch acetate which SD was nearly 1.5, on the other hand.

The obtained compounds were conditioned for a week at a temperature of 20°C and a relative humidity (RH) of 65 % before being injected into standardized samples. Tensile tests (ISO/R 527) and Charpy impact tests (ISO/R 179) were carried out on these samples which had first been conditioned for a week at 20°C and 65 % RH. The results obtained were analysed. The dimensional stability was estimated by determining the voluminal shrinkage after the moulded samples had been kept for a week at 20°C and 65 % RH.

The hydrophobic behaviour was evaluated thanks to an empirical test called “water-test”. This behaviour was also evaluated using a computer drived goniometer, by measuring ø which is the “Water-Substrate” contact angle. This study has shown that starch is not compatible with the 2.3 SD cellulose acetate.

That is why these blends exhibit a skin of cellulose diacetate which provide materials with a definite improvement in hydrophobic behaviour. This study has also shown that starch is compatible with the 1.5 SD starch acetate.

Therefore these blends seem to be homogeneous and do not exhibit a skin-core structure, so that the provided materials are less hydrophobic than the previous one.