Effect of different preparation methods on structure and properties of chitosan/poly-lactic acid blend porous membrane

• Published in: Journal of porous materials 2012-12, Vol.19 (6), p.1015-1022
• Main Authors: Zuo, Dan-Ying, Li, Hong-Jun, Liu, Hong-Tao, Zhao, San-Ping
• Format: Article
• Language: English
• Subjects: Blends; Catalysis; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Chitosan; Diffusion; Mathematical models; Membranes; Physical Chemistry; Porosity; Scanning electron microscopy; Swelling
• ISSN: 1380-2224; 1573-4854
• DOI: 10.1007/s10934-012-9564-3

Two kinds of blend solutions were used to prepare chitosan (CS)/poly- l -lactic acid (PLLA) blend membranes by the immersion precipitation phase inversion method. CS/PLLA blend membrane was fabricated by mixing CS-acetic acid solution and PLLA-dioxane solution, chitosan powder (CSP)/PLLA blend membrane was fabricated by mixing CSP and PLLA-dioxane solution. The membrane structure and properties were characterized by Scanning Electron Microscope, Wide Angle X-ray Diffraction, porosity, water vapor transmission rate and swelling property. The results showed that CS content in CSP/PLLA blend membrane was nearly 70 times higher than in CS/PLLA blend membrane. Two types of blend membranes took on an unsymmetrical structure with a skin layer, a microvoid sub-layer and a porous bottom surface. But CSP/PLLA blend membrane exhibited a porous skin layer, while the skin layer of CS/PLLA blend membrane was impact. The WAXD analysis revealed that PLLA and CS were amorphous in CS/PLLA blend membrane, while there were PLLA and CS crystalline in CSP/PLLA membrane, which resulted in the higher initial modulus of CSP/PLLA blend membrane. The porosity, WVTR and equilibrium swelling ( Q eq ) of CSP/PLLA blend membrane were higher than that of CS/PLLA blend membrane, especially Q eq . The swelling kinetics results showed that in the initial swelling, water molecules diffusion followed Non-Fickian diffusion for CS/PLLA blend membrane swelling, and the swelling of CSP/PLLA blend membrane fitted with the relaxation diffusion model. The swelling kinetics studies for whole swelling revealed that the swelling degree and the initial swelling rate of CSP/PLLA membrane were significantly higher than that of CS/PLLA membrane, although the total swelling rate of CSP/PLLA blend membrane decreased lightly.