Cellulose ester/polyolefine blends

The Ph.D. of François Besson within the Industrial Chair in Bioplastics will be focused on polymer blends of oil-based commodity polymer (polyolefins) and biomass-based polymers (cellulose derivatives esters).

The objective is :
  • to replace a part of the oil-based plastic by a modified natural polymer like cellulose derivatives esters
  • to create new non-biodegradable materials with improved properties. If the processing of a blend is well understood and mastered, this blend will have better properties than the ones of the initial single components.

Development of these materials will allow – in the end – finding new outlets for cellulosic plastics, for a long time abandoned in favor of petrochemical plastics.

Main topics of polymer blending will be studied :
  • formulation (compatibilisation),
  • molten state processing of the multiphasic blends,
  • control of their morphologies,
  • rheological properties,
  • mechanical properties.

Particular attention will be paid on understanding the development of blends morphologies, responsible for major properties of the blends (and more particularly mechanical properties). Rheometry and rheo-opticals will be two very useful methods to establish structure/properties correlations.

In a first approach, initial single components will be separately studied and each property needed for the blend will be evaluated.
The second part will deal with blends between the two single components without compatibiliser. Parameters influencing the morphology will be described. Rheological and mechanical properties of the uncompatibilised blends will be tested.
In a third part, compatibilised blends will be studied. For example, maleic anhydride grafted polyethylene will be used as a compatibiliser. A more detailed analysis of parameters influencing morphologies will be performed: influence of the nature of the cellulose ester, concentration of compatibiliser, processing conditions (temperature, mixing time, shearing), influence of the composition…
Finally, mechanical tests will be performed to establish relationships between blends morphology and their solid-state properties.

nodular morphology of cellulose ester
Example of a nodular morphology of cellulose ester (Cellulose Acetate Butyrate) in a polyolefine matrix (High Density Polyethylene), without compatibiliser, observed with a scanning electron microscope. The cellulose ester represents 15% weight of the blend and appears as “white” droplets.

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