Development of novel eco-efficient electrospun poly (lactic acid) membranes

  • Lin Li

Student thesis: Master's Thesis

Abstract

Environment-friendly membranes were fabricated from poly (lactic acid) (PLA) via the electrospinning technique. The electrospinning parameters that affect the membrane structure, fibers morphology, and other membrane properties were identified to obtain the best performance data. In order to both control the pore size of the electrospun membranes and improve their mechanical properties, a series of annealing treatments were carried out on the one-layer electrospun membrane. The effect of annealing treatment on membrane structure, porosity, hydrophobicity and mechanical properties was investigated. When either annealing time or temperature was increased, membrane shrinkage and the fiber thickening and fusion were observed, which resulted in pore size reduction from 2.8μm to 0.9μm, along with a reduced porosity. On the other hand, annealing resulted in an increase in the membrane’s mechanical strength, as measured by the Mullen burst test. Moreover, the Young’s modulus of the annealed membranes increased dramatically by about 2500%. However, due to the negative effect of annealing treatment on the membrane porosity and hydrophobicity, hot pressing was employed alternatively to improve the membrane properties for Membrane Distillation. The effect of membrane thickness on the pore size was investigated to optimize the pore size. It was found that the thicker membrane with more layers had smaller pore size than that of thinner membranes with fewer layers. Furthermore, suitable hot pressing temperature and hot pressing procedure were identified. Then the comparisons of membrane morphology, pore size, contact angle, thickness and porosity were carried out among the hot pressing only, annealing treatment only and combination of both in different order. It was found that hot pressing only is preferred from the view of pore size, porosity and contact angle for Membrane Distillation. Finally, based on the properties of the electrospun and annealed PLA membranes, they were proposed as microfiltration membranes. The filtration tests showed that the annealing treatment, which varied the membrane properties, had a significant impact on membrane performance, in terms of both flux and particle rejection.
Date of AwardJun 2013
Original languageAmerican English
SupervisorHassan Arafat (Supervisor)

Keywords

  • Fibers; Organic Materials (Polymers); Electrospinning.

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