Structure variation and properties enhancement of uniaxial stretching poly(l‐lactic acid)/eggshell powder composites

Abstract

ABSTRACTBiodegradable poly(l‐lactic acid) (PLLA)/eggshell (ES) powder composites were prepared by melt blending and uniaxial stretching above the glass‐transition temperature of PLLA. Scanning electron microscopy analyses revealed that micropores appeared in stretched composites. Porosity was affected by two factors, stretch ratios, and ES contents. Differential scanning calorimetry and wide‐angle X‐ray diffraction results demonstrated that strain‐induced crystallization in α‐form could be achieved in PLLA matrix. This superstructure improved multifunctional performance of PLLA composites. The exceptional combination of strength, modulus, and ductility of stretched PLLA90/ES10 composites with a stretch ratio of 6 were demonstrated, exceeding neat PLLA with the increments of 148, 190, and 507% in breaking strength, modulus, and elongation at break (140.8 MPa, 3810 MPa, and 35.2%), respectively. Meanwhile, the enhancement of thermomechanical properties due to high crystallinity and controllable degradation rates resulting from porosity were obtained by adjusting the composites compositions and/or stretch ratios. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48158.