Date

5-1-2018

Document Type

Thesis

Degree

Master of Science

Department

Polymer Science and Engineering

First Adviser

Pearson, Raymond A.

Abstract

Polylactic acid (PLA) is perhaps one of the best known polymers produced from renewable raw materials such as sugar cane and corn starch. Several studies have focused on improving the properties of PLA by incorporating nanofillers in polymer matrix. Cellulose nanocrystals (CNC) is a nanofiller from natural sources (typically wood pulp) that is used to reinforce and modify the mechanical properties and biodegradability of PLA. In this work, cellulose nanocrystals (CNC) reinforced polylactic acid composite was produced in 1, 2, 5 and 10 wt % CNC content by a single-screw extruder in filament form. The effect of cellulose content on the thermal properties of the bio-composite were studied. Differential scanning calorimetry results showed shift in the glass transition temperature and a change in the melting temperatures, where 10% CNC content showed highest reduction in melting temperature. Cellulose proved to increase the crystallinity of the matrix compared to the neat PLA, 1% cellulose exhibited the highest cold crystallization peak. Precision filament (1.75 mm in diameter) was made for fused deposition modeling (3D printing) in order to study the mechanical properties of the bio-composites. The tensile modulus increased in 1% cellulose composites (4.55 GPa) compared to neat PLA (3.03 GPa) for the printed samples. However, the elongation at break reduced when comparing neat PLA (8.7%) while in 1% cellulose was (2.9%).

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