Quantification of the confinement effect on the amorphous mechanical properties in semi-crystalline polymers using combined experimental techniques

摘要

The effect of amorphous phase confinement onto the viscoelsatic properties of two polymers, Polyethylene terephthalate (PET) and poly(lactic acid) (PLA) was investigated. Based on small angle X-ray scattering (SAXS), differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) experiments, the micro-structure of the amorphous and crystalline phase, the rigid amorphous fraction, and the viscoelastic mechanical properties of the different semi-crystalline samples were investigated. DSC helps quantifying the rigid amorphous fraction dependence on the crystallinity. DMA leads to quantify the viscolelastic properties of the mobile and rigid amorphous phases. This result was correlated with the amorphous phase thickness distribution determined by SAXS. This observation was bolstered based on literature results about geometrical confinement configurations and their effect on the glass transition temperature of polymeric materials. This work, beyond the comparative study between PET and PLA help the mechanical quantification of the amorphous confinement effect in semi-crystalline polymers which could be used as input for micromechanical modeling for predictive mechanical and thermo-mechanical behavior laws.