Toughening of Polylactide (PLA): Routes towards Improvement in Mechanical Properties and Toughness

Abstract

This thesis is about the toughening of poly lactide (PLA). PLA has the potential to be of great importance to the materials world, not only as a solution to address pollution wastes of plastics, but also as a best candidate to be derived from non-petroleum based and renewable resources. The most significant drawback of PLA is its brittleness, which is the focus of the present thesis. Chapter 1 is literature review that focuses mainly on available data on the connections between structure-property relationship of PLA and PLA nanocomposites, and toughening. Chapter 2 entitled: “Improving the Mechanical Properties of Polylactide: Embrittlement or Plasticization?” investigates two conventional methods. These methods are adding nanoclays and plasticizer to control mechanical properties. In Chapter 3, entitled: “Toughening of Polylactide: Single or Hybrid Fillers?” the first steps towards finding a feasible method for improvement in PLA toughness are introduced. The main aim is to improve toughness without sacrificing mechanical properties such as tensile strength and modulus. New ternary PLA nanocomposites introduced in chapter 3 are comprehensively investigated as a main idea in Chapter 4 entitled: “Tensile properties of ternary PLA/EGMA/nanoclay hybrid composites with controlled morphology”. Chapter 5, entitled: “Influence of Phase Microstructure on Mechanical Properties of Ternary Polylactide (PLA) Nanocomposites”, and Chapter 6, entitled: “Effect of Mixing Sequence in the Preparation of PLA/EGMA/Nano-Clay Hybrid Composites” focuses mostly on morphology control. Chapter 7 intends to reach a new milestone for the project. Its main goal is to address one of the most important missing links: “biodegradability”. It is interesting to claim that, for the first time, 100% toughened biodegradable PLA composites has been developed.