Amidons thermoplastiques lubrifiés entièrement biodégradables. Propriétés mécaniques et rhéologiques d’un grade injection

Fully biodegradable lubricated thermoplastic wheatstarch: mechanical and rheological properties of an injection grade

¹ IFTS (Charleville)
² Assistante d’ingénieur, GREPAC, Reims
³ Maître de conférence ESIEC, Reims
⁴ Professeur de chimie industrielle, directeur du GREPAC, Reims

Abstract

Pellets were made by extrusion from lubricated and fully biodegradable thermoplastic wheatstarch formulations. The used lubricants were vegetable oil or internal biodegradable release agent such as magnesium stearate.

After conditioning one week long at 20°C and under 65 % of relative humidity (RH), these pellets were injected to produce ISO / R 527 standardized samples for tensile test, (150 mm long and 4 mm thick).

Such samples were conditioned in the same way as pellets were and allowed us to quantify the mechanical properties and moulding shrinkage of these fully biodegradable materials.

The automatic injection mode is only possible with pellets lubricated with magnesium stearate. This is the reason why this formulation will be therefore considered as a “reference injection grade”.

The rheological study of this reference emphasizes, all other things being equal, that the injection parameters depend on the relative humidity of the conditioning atmosphere in which the pellets remained before injection.