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PLA Melt Stabilization by High-Surface-Area Graphite and Carbon Black
Luciana D'Urso1, Maria Rosaria Acocella2, Gaetano Guerra3
1Department of Chemistry and Biology, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano (SA), Italy. ldurso@unisa.it.
Polymers
|April 11, 2019
Summary
Adding small amounts of carbon black (CB) or graphite (HSAG) prevents molecular weight reduction in biodegradable poly(lactic acid) (PLA) during melt processing. Carbon black is particularly effective, maintaining PLA
Area of Science:
- Polymer Science
- Materials Science
- Nanotechnology
Background:
- Poly(lactic acid) (PLA) is a widely used biodegradable polymer.
- Melt processing of PLA often leads to significant molecular weight reduction and degradation.
- This degradation limits PLA's applicability in various manufacturing processes.
Purpose of the Study:
- To investigate the use of carbon nanofillers to prevent degradation of PLA during melt processing.
- To evaluate the effectiveness of high-surface-area graphite (HSAG) and carbon black (CB) as stabilizers.
- To understand the mechanism behind the stabilization effect.
Main Methods:
- Rheological measurements (melt viscosity, time sweep-complex viscosity) during extrusion.
- Gel permeation chromatography (GPC) to assess molecular weight changes.
- Thermogravimetric analysis (TGA) to evaluate thermal stability.
Main Results:
- Compounding PLA with small amounts of HSAG or CB significantly reduced degradation during melt processing.
- As little as 0.1 wt % CB maintained PLA's molecular weight during extrusion.
- Carbon fillers likely stabilize PLA by scavenging water, inhibiting hydrolysis.
- TGA showed fillers slightly decrease thermal decomposition temperatures, but above processing conditions.
Conclusions:
- Carbon nanofillers, especially carbon black, are effective stabilizers for poly(lactic acid) during melt processing.
- This stabilization is attributed to the inhibition of hydrolytic degradation.
- The findings offer a method to enhance the processability and durability of biodegradable PLA.
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