Eco-Efficient Biodegradable Composites

  • Sanaa Iqbal Pirani

Student thesis: Master's Thesis

Abstract

Cellulose consists of amorphous and crystalline regions. During the acid hydrolysis of cellulose, its amorphous regions are hydrolyzed and degraded into soluble products while the crystalline regions remain intact, giving nanocrystalline cellulose (NCC). In an effort to make the NCC extraction process more feasible, a new process was developed to recover and utilize the hydrolyzed regions of cellulose as a byproduct. The acid hydrolyzed amorphous regions were separated and then regenerated into solid particles. XRD data revealed that the recovered material is characteristic of cellulose II. Hydrolysis conditions were optimized to maximize the yield of the recovered material and at the same time produce NCC material. Preliminary experiments showed yield values of approximately 61% for the cellulose I crystalline portions and values of about 21% for the recovered material. Enzymatic hydrolysis experiments of the recovered material revealed high susceptibility to enzymatic hydrolysis which makes it a promising source for biofuels production. Biodegradable nanocomposites of NCC and electrospun PLA were prepared with the advantage that the electrospun PLA helped improve the dispersion of hydrophilic NCC in hydrophobic PLA. The composites, prepared using mechanical homogenization and heat pressing, were found to have structural integrity and they all displayed an improvement in mechanical properties (relative to the sample without any NCC). The optimum compositions were in the 0.5-3% NCC range. Biodegradable nanocomposites of poly(lactic acid) (PLA) and nanoclay samples were prepared using extrusion followed by injection molding. The samples were investigated using Dynamic Mechanical Analysis (DMA), tensile testing and Differential Scanning Calorimetry (DSC). The combination with 3% nanoclay was found to be optimum as a result of having the greatest mechanical strength. The fracture surfaces of the samples were also observed with the help of a Scanning Electron Microscope (SEM) and more ductile fractures for those samples with greater mechanical strength were evident. In addition, it was found that the trend followed by the glass transition temperature values obtained for the composites by both DSC and DMA was the same. Finally, the composites investigated affirmed their potential to be used in packaging and tissue engineering applications as a biodegradable alternative to fossil fuel based polymers.
Date of Award2012
Original languageAmerican English
SupervisorRaed Hashaikeh (Supervisor)

Keywords

  • Cellulose Acetate
  • Eco-Labeling
  • Composites Materials

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