Study of the Miscibility of Polymer Blends: Its Influence on the Morphology and Efficiency of Membranes
Name: RAYANNE PENHA WANDENKOLKEN LIMA
Publication date: 03/12/2024
Examining board:
Name |
Role |
|---|---|
| ADILSON RIBEIRO PRADO | Examinador Externo |
| CLEOCIR JOSE DALMASCHIO | Examinador Interno |
| ELOI ALVES DA SILVA FILHO | Presidente |
| LUIZ CARLOS PIMENTEL ALMEIDA | Examinador Externo |
| MARTA ALBUQUERQUE MACHADO | Examinador Interno |
Summary: Sustainability, understood as social and environmental responsibility, is a fundamental principle for mitigating the environmental challenges associated with the production and disposal of plastics. In this context, the present work aims to correlate the morphology of membranes obtained via Non-Solvent Induced Phase Separation (NIPS) from polymer blends with the miscibility analysis of the blends themselves. Two blends were prepared for this purpose: the first composed of two semi-crystalline polymers, one of recycled origin and the other of green origin; and the second composed of one semi-crystalline polymer and one amorphous polymer, both recycled. The miscibility of the blends was evaluated using DSC and confirmed through dynamic mechanical analysis (DMA). The first blend demonstrated partial immiscibility, with a reduction in the equilibrium melting temperature (Tºm) and showed three glass transition peaks (Tg), indicating separate phases. The Flory-Huggins interaction parameter (12) for this blend was positive (1.115 × 10), indicating a barrier to total miscibility. The resulting membranes presented a dense, spongy and homogeneous morphology, with macrovoid formation. Permeability and porosity analyses indicated potential for nanofiltration or reverse osmosis applications. Meanwhile, the second blend exhibited two Tg peaks, suggesting miscibility relative to its composition, with a negative 12 (-2.057 × 10), indicating favorable interactions, though insufficient for complete miscibility. Morphological analysis of these membranes revealed the presence of macrovoids associated with partial immiscibility and thermodynamic instability, resulting in lower selectivity and mechanical resistance. These characteristics classify them for ultrafiltration-type applications.
