A new perspective and comparative study on demixing and gelation behavior of cellulose acetate, cellulose acetate propionate and cellulose acetate butyrate ternary solutions

Abstract

Cellulose acetate (CA), cellulose acetate propionate (CAP), and cellulose acetate butyrate (CAB) were fabricated as membrane via nonsolvent induced phase separation process. N,N‐Dimethylformamide (DMF) and N,N‐Dimethylacetamide (DMAc) as solvents and water as nonsolvent were employed. Ternary phase diagrams for all six ternary systems were constructed using Flory‐Huggins theory. In this way, cloud points as well as Berghman's points were determined. Modulus of polymers steepened in various concentration of solvent/nonsolvent mixtures were measured to find the weight fraction of polymer (wp) in which vitrification takes place. WP values for CA, CAP, and CAB were obtained 0.59, 0.67, and 0.74 in presence of DMF while those were 0.69, 0.74, and 0.84 in presence of DMAc; whereas glass transition temperatures (Tg) for three polymers were determined 180°C, 142°C, and 101°C correspondingly. Pure water flux for CA, CAP, and CAB membrane increased from 75.7 to 83.4 and 290.3 and from 109.6 to 116.1 and 400.3 L/m2 h bar when DMF and DMAc were used as solvents, respectively. Results revealed that as Tg of polymer decreases, the membrane structure vitrifies at higher polymer concentration with more porous structure, bigger pores, higher permeate flux followed by decrease in mechanical strength. POLYM. ENG. SCI., 58:1135–1145, 2018. © 2017 Society of Plastics Engineers

Evaluation of solubility parameters and relative energy difference (RED) on the preparation of polysulfone/polyethylene glycol membrane: A study on the casting solution and coagulation bath

“…Hansen solubility parameters for the binary mixture of coagulation bath; Water: DMAc (100:0, 70:30, 50:50, and 40:60) was calculated with equation (3). Where X = molar fraction δ = Solubility parameter V = molar volume which for DMAc is 92.68 27 and for water is 18 (cm 3 /mol) 28 After determining δ d , δ p , and δ h , R a of binary mixture coagulation baths was calculated via equation (1). Finally, according to the R 0 of polymeric solution, the RED of coagulation baths for the polymeric blends (P0, PP3, PP15, and PP35) was calculated.…”

Construction of efficient desalting layer on a cellulose acetate membrane by acetalized surface crosslinking treatment

“…Esterification or etherification of cellulose is the two main modification methods currently used to prepare cellulose derivatives. The hydrogen bonds within the modified cellulose derivatives are greatly reduced, which can effectively enhance their solubility and melt processing performance, and are widely used in medicine, food, artificial tissues, among other fields .…”