This study explains the different factors affecting formation of membrane morphologies at varying solvents concentrations and non-solvent temperatures. At elevated temperatures, the process of liquid-liquid demixing dominated membrane formation. For dopes with γ-butyrolactone, crystallization influenced the formation of integrally skinned asymmetric membranes even at elevated temperatures. From the crystallinity studies, the formation of a particulate morphology did not ensure that a more organized and highly crystalline sample can be obtained.