PLA

Definition

PLA, or Polylactic Acid, is a biodegradable and renewable thermoplastic aliphatic polyester derived from renewable resources such as corn starch or sugarcane. It is a key term in the context of 21.9 Polyamides and Polyesters: Step-Growth Polymers, as it is an important type of step-growth polymer.

5 Must Know Facts For Your Next Test

1. PLA is synthesized through the polymerization of lactic acid, which is derived from the fermentation of agricultural byproducts like corn starch or sugarcane.
2. PLA exhibits good mechanical properties, transparency, and heat resistance, making it suitable for a variety of applications such as packaging, biomedical devices, and 3D printing.
3. The biodegradable nature of PLA makes it an environmentally friendly alternative to traditional petroleum-based plastics, as it can be composted or recycled at the end of its useful life.
4. PLA is a semi-crystalline polymer, with the degree of crystallinity affecting its physical and thermal properties, such as melting point and tensile strength.
5. The production of PLA requires less energy and emits fewer greenhouse gases compared to the production of conventional petroleum-based plastics.

Review Questions

• Explain the significance of PLA being a step-growth polymer and how this relates to its synthesis and properties.
  • PLA is a step-growth polymer, meaning it is formed through a step-wise reaction of monomers with two or more functional groups. This step-growth polymerization process allows for the controlled synthesis of PLA, enabling the tailoring of its molecular weight and, consequently, its physical and mechanical properties. The step-growth nature of PLA polymerization also contributes to its biodegradable characteristics, as the ester linkages can be broken down by enzymatic or hydrolytic processes.
• Describe the relationship between the renewable and biodegradable nature of PLA and its environmental impact.
  • PLA is derived from renewable resources, such as corn starch or sugarcane, making it a sustainable alternative to traditional petroleum-based plastics. Additionally, PLA is biodegradable, meaning it can be broken down by the action of living organisms, allowing for its composting or recycling at the end of its useful life. This closed-loop life cycle of PLA reduces its environmental impact compared to non-biodegradable plastics, as it does not contribute to the accumulation of plastic waste in landfills or oceans. The renewable and biodegradable properties of PLA make it a more environmentally friendly option for various applications, particularly in the packaging and biomedical industries.
• Analyze how the specific properties of PLA, such as its degree of crystallinity and thermal characteristics, influence its suitability for different applications.
  • The properties of PLA, such as its degree of crystallinity and thermal characteristics, can be tailored through the control of its synthesis and processing. The semi-crystalline nature of PLA affects its physical and mechanical properties, with a higher degree of crystallinity generally leading to increased tensile strength, stiffness, and melting point. These properties can be leveraged to make PLA suitable for various applications. For example, more crystalline PLA may be preferred for packaging applications that require higher mechanical strength and heat resistance, while amorphous PLA may be better suited for biomedical devices that need to be more flexible and malleable. The ability to fine-tune PLA's properties through synthesis and processing allows it to be adapted to the specific requirements of different industries and end-uses.

Related terms

Step-Growth Polymerization: A type of polymerization reaction where monomers with two or more functional groups react in a step-wise fashion to form long polymer chains.

Aliphatic Polyesters: A class of polymers containing ester linkages in the main chain, where the carbon backbone is composed of straight or branched chains.

Biodegradable Polymers: Polymers that can be broken down into simpler substances by the action of living organisms, such as bacteria or fungi.