Document Type

Thesis - Open Access

Award Date

2018

Degree Name

Master of Science (MS)

Department / School

Agricultural and Biosystems Engineering

First Advisor

Lin Wei

Abstract

Most of current food packaging resources are non-renewable and nonbiodegradable. The use of these materials has resulted in serious environmental issues. In recent years, the recognition of waste disposal problems and their impacts on the environment has risen the demand for packaging manufactured from renewable materials. However, there are some limitations of using biopolymers for food packaging applications. These limitations include unreliable mechanical and barrier properties. These issues may be addressed by combining biopolymers and nanotechnologies. Nanotechnologies are expected to improve the performance of biopolymer-based packaging materials for food packaging applications. Cellulose nanocrystals (CNC) has shown a potential to be implemented as filler to reinforce synthetic polymer for food packaging applications, equating its unique attributes of biodegradability high surface area. In this work, the aim is to develop a friendly environmental nanocomposite film based on combination of polylactic acid (PLA) and CNC for food packaging applications using a solvent casting method. The main problem that restricts the utilization of nanocellulose as a reinforcing filler with hydrophobic polymers is their tendency to aggregate in the polymer matrix. Thus, a homogenization process was applied to the mixture in order to obtain an even dispersion of CNC in the PLA matrix. Three various internal mixtures at CNC content were used to prepare the nanocomposite films, which are 1,3,5 wt%. The prepared nanocomposite films were subjected to morphological analysis, tensile strength, water vapor, and moisture uptake tests. These tests were conducted to test CNC impact on the barrier and mechanical properties of the PLA matrix. The results of scanning electron microscope (SEM) images showed an appropriate dispersion of CNC at low concentration 1% and 3%, while aggregations of CNC were observed in the PLA matrix for the film containing 5%CNC. The tensile strength of the nanocomposite films significantly improved only with the film containing 3% of CNC by 40% compared to the control sample. The water vapor test conducted on the prepared films reviled an improvement of water vapor behavior of the film containing 3%CNC and 5%CNC by 20% and 42% respectively. The water uptake test reviled that the water sensitivity of the nanocomposite films increased with the presence of CNC at different contents (1%,3% 5%) in the PLA matrix. The obtained results from this study indicated that the prepared nanocomposite films presented relatively reliable tensile strength and water permeability compared to the pure PLA film. The improvement of the water permeability and the tensile strength showed a potential of the prepared nanocomposite films to be utilized in food packaging applications. However, further studies on the nanocomposite films properties required to confirm that.

Library of Congress Subject Headings

Food packaging machinery industry.
Polylactic acid.
Nanocomposites (Materials)
Biopolymers.

Description

Includes bibliographical references

Format

application/pdf

Number of Pages

69

Publisher

South Dakota State University

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Rights Statement

In Copyright