Elaboration, morphology and properties of renewable thermoplastics blends, based on polyamide and polyurethane synthesized from dimer fatty acids

• Biobased blends are elaborated from TPU and PA (DAPA), based on dimers fatty acids.
• The addition of DAPA into TPU brings different positive effects.
• “Morphology-properties” relationships of these systems were investigated.
• Discontinuous and co-continuous structures obtained according to TPU/DAPA ratio.
• When TPU content is close to 40 wt%, a co-continuous morphology takes place.

Two different thermoplastics, polyurethane (TPU) and polyamide (DAPA), have been elaborated by polymerisation from dimers of fatty acids. Since the addition of DAPA into the TPU matrix brings different positive impacts such as a higher biobased content and a lower density of the final system, different multiphase systems have been elaborated by blending both biobased polymers. Different polymers ratios have been mixed in controlled thermo-mechanical conditions. The analysis of the corresponding thermal properties allows to investigate the miscibility and interactions between both phases. Rheological measurements (melt) and mechanical tests (solid state) were also used to understand better the “morphology-properties” relationships of these biobased systems. An increase of the mechanical performances (Young’s modulus, yield stresses) were observed as DAPA content increases in the systems. For specific ratios, a co-continuous structure was observed by electronic microscopy after selective extraction. Simple models have been used to simulate the mechanical properties of these systems vs. the polymers contents.

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