Improvement of the strength and toughness of biodegradable polylactide/ silica nanocomposites by uniaxial pre-stretching

Highly toughened polylactide (PLA) nanocomposites with balanced stiffness and strength were successfully prepared by combining the modification of 5 wt% silica (SiO2) nanoparticles and uniaxial pre-stretching. The PLA/5 wt% SiO2 nanocomposites fractured in a brittle way due to the network structure composed of cohesional entanglements. After pre-stretching, the elongation at break was increased to 168% at pre-stretching ratio (PSR) of only 0.5, which should be attributed to the destruction of the network structure of cohesional entanglements. With the increment of PSR, the modulus and tensile strength were improved obviously (2725 MPa, 101.6 MPa at PSR = 2.0) while the elongation at break (56% at PSR = 2.0) reduced gradually because of the formation of orientation and mesophase. However, the elongation at break was still larger than that of undrawn PLA (5.4%) and undrawn PLA nanocomposites (7.2%), indicating that the uniaxial pre-stretching was an effect way to strengthen and toughen PLA nanocomposites.

Automated summary

This study successfully prepared highly toughened polylactide (PLA) nanocomposites with balanced stiffness and strength by modifying silica (SiO2) nanoparticles and conducting uniaxial pre-stretching. The pre-stretching process increased the elongation at break and strength while reducing the ductility gradually, indicating the effectiveness of uniaxial pre-stretching in strengthening and toughening PLA nanocomposites.