5:15pm - 6:15pm
Room 711 Havemeyer
New York, NY 10027
Polylactide (PLA) currently represents one of the most industrially relevant bio-based polymers produced on scale and has unique properties such as high modulus (similar to PET), biocompatibility and biodegradability. Despite PLA’s numerous advantages, it suffers from a low heat distortion temperature (HDT), prohibiting its use for more demanding engineering applications. One potential strategy to increase PLA’s HDT is through the fabrication of PLA based nanocomposites. During the past decade, Cellulose Nanocrystals (CNCs) have emerged as an exciting new class of nanoparticles due to many attractive features when compared to other nanoparticles including natural abundance, non-toxicity and, low density. CNC surfaces are also covered with reactive hydroxy groups, facilitating modification reactions. Unfortunately, due to the polar nature of CNCs, they tend to aggregate during melt processing with PLA, thus making modification reactions necessary.This presentation describes the modification of CNCs via two different methods: 1) a novel one-pot Fischer esterification/acid hydrolysis procedure and, 2.) grafting of PMMA from the CNC surfaces. PLA/CNC nanocomposites were produced by direct melt blending, and LA-CNCs showed superior reinforcement in both below and above the glass transition temperature of PLA. The addition of 20% LA-CNCs resulted in a 20°C increase in PLAs HDT. Building on this work, and the miscibility of PLLA and poly(methyl methacrylate) (PMMA). CNC surfaces were modified with PMMA chains using a grafting “from” strategy.Dynamic rheology and TEM showed that PMMA grafts enhanced CNC dispersion in PLA by melt blending. PLA nanocomposites containing just 5% of CNC-graft-PMMA had HDT values >100°C. PLA/CNC nanocomposites using modified CNCs are expected to increase PLAs market share to more durable applications.
Wednesday, February 13, 2019 at 5:15pm
Room 711 Havemeyer
Department of Chemistry, Columbia University, Havemeyer Hall, 3000 Broadway, New York, NY 10027, USA | 212-854-2202 | http://chem.columbia.edu/