CTA III: A Third Polymorph of Cellulose Triacetate

Braun, Jennifer L.; Kadla, John F.

doi:10.1080/07328303.2012.752493

Cited by 19 publications

(12 citation statements)

References 25 publications

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“…In order to characterize the used CTA, the XRD (Cu‐Kα) pattern was measured; good agreement with the literature patterns was found. By fitting the pseudo‐Voigt functions to the XRD peaks, the pattern revealed four overlapping peaks having maxima of 2 θ at 8.6, 12.4, 17.0, and 21.4° (Fig.…”

Section: Resultssupporting

confidence: 70%

“…Contrarily, PTMSP, which is a high free volume polymer, does not show clear glass transition at temperatures below 250 °C and softens (undergoes geometric isomerization and/or decomposition) at 300–370 °C. Also the XRD pattern of PTMSP is less complex than that of CTA and shows two major peaks while CTA shows four major peaks . Thus, the arrangement of polymer chains in bulk PTMSP is presumably more rigid than that in bulk CTA.…”

Section: Introductionmentioning

confidence: 96%

“…The tested polymers have markedly different physicochemical properties, namely the glass transition temperature, melting temperature and XRD pattern. The broad ranges of glass transition temperature ( T g ∼160–205 °C) and the melting temperature ( T m ∼230–306 °C) of CTA reflect the polymorphism and relaxation phenomena occurring in this polymer. Contrarily, PTMSP, which is a high free volume polymer, does not show clear glass transition at temperatures below 250 °C and softens (undergoes geometric isomerization and/or decomposition) at 300–370 °C.…”

Section: Introductionmentioning

confidence: 99%

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Sorption of methanol, dimethyl carbonate, methyl acetate, and acetone vapors in CTA and PTMSP: General findings from the GAB Analysis

Vopička

Pilnáček

Číhal

et al. 2015

J. Polym. Sci. Part B: Polym. Phys.

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Sorption of vapors of four organic compounds in two glassy polymers, cellulose triacetate (CTA) and poly [(trimethylsilyl)propyne] (PTMSP), has been reported and analyzed in terms of Guggenheim-Anderson-De Boer (GAB) model. These two structurally and physicochemically different glassy polymers both independently showed that one sorption site was formed by about three monomeric units. This finding held true for vapors of all characterized compounds; that is, for methanol, for its derivatives dimethyl carbonate and methyl acetate, and for acetone. The "rule of three" might thus also be applicable to other sorbates and glassy polymers. Further, an original modification of the GAB model for the sorption of alcohols in PTMSP was derived and successfully tested. Overall, the analyses of the sorption isotherms, heats of sorption and diffusion coefficients supported the view that the sorption of vapors in glassy polymers has adsorptive nature.

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Section: Resultssupporting

confidence: 70%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Sorption of methanol, dimethyl carbonate, methyl acetate, and acetone vapors in CTA and PTMSP: General findings from the GAB Analysis

Vopička

Pilnáček

Číhal

et al. 2015

J. Polym. Sci. Part B: Polym. Phys.

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“…It is well known that the CTA polymer can contain areas of crystallinity. WAXD analysis was consistent with these reports with two typical semi-crystalline peaks observed at 2 ~ 10 o [35,44,45] and 17 o [46,47], and a van der waals amorphous halo at 20 -21 o [45,46,48,49] in the fresh CTA membrane ( Figure 5). By using an X-ray diffraction deconvolution method [50], the crystallinity index of this membrane was calculated to be 56 ± 5% which is compatible with the literature [51].…”

Section: The Impact Of Glycols On the Glass Transition Temperature Ansupporting

confidence: 89%

The impact of ethylene glycol and hydrogen sulphide on the performance of cellulose triacetate membranes in natural gas sweetening

Kanehashi

Scholes

et al. 2017

Journal of Membrane Science

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In natural gas sweetening, gas dehydration with glycols is typically carried out upstream of membrane separation of carbon dioxide. This means that when process upsets occur, these glycols can reach the membrane unit. In this work, we study the impact of two common glycols (monoethylene glycol and triethylene glycol) on the gas transport performance of CTA. We find that the glycol absorbed into the membrane initially obstructs the permeation of CH 4 and CO 2, due to pore filling or antiplasticisation effects, but the permeability then increases again, indicative of polymer relaxation and a loss of crystallinity in the polymer. The smaller helium molecule is significantly less affected by the presence of the glycols, possibly because its lower solubility within glycol limits its movement through the swollen structure. However, after removing the glycols with a methanol wash, the membrane performance recovers with only a slight residual plasticisation observed. In addition, the permeation of H 2 S, a common contaminant within natural gas streams, was studied across a range of temperatures. At the partial pressures studied (up to 0.75 kPa), H 2 S had very little effect on the membrane performance even in long-term exposure for up to 300 days.

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“…The physical properties of CAs are determined by the conformational behavior of the chains and their intermolecular interactions. Chemically homogeneous sequences of un-derivatized or fully derivatized glucopyranose units can locally organize into a crystalline structure; whereas the heterogeneous ones comprised of differently substituted monomers randomly distributed along the chain, are amorphous [6,7]. X-ray diffraction observations revealed that the water-soluble CA is essentially noncrystalline [3].…”

Section: Introductionmentioning

confidence: 99%

Partially Acetylated Cellulose Dissolved in Aqueous Solution: Physical Properties and Enzymatic Hydrolysis

et al. 2019

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Cellulose acetate is one of the most important cellulose derivatives. The use of ionic liquids in cellulose processing was recently found to act both as a solvent and also as a reagent. A recent study showed that cellulose dissolution in the ionic liquid 1-ethyl-3-methylimidazoliumacetate (EMIMAc) mixed with dichloromethane (DCM) resulted in controlled homogenous cellulose acetylation; yielding water-soluble cellulose acetate (WSCA). This research investigated the properties of cellulose acetate prepared in this manner, in an aqueous solution. The results revealed that WSCA fully dissolves in water, with no significant sign of molecular aggregation. Its conformation in aqueous solution exhibited a very large persistence length, estimated as over 10 nm. The WSCA exhibited surface activity, significantly reducing the surface tension of water. Because of the molecular dissolution of WSCA in water, augmented by its amphiphilicity, aqueous solutions of WSCA exhibited an overwhelmingly high rate of enzymatic hydrolysis.

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CTA III: A Third Polymorph of Cellulose Triacetate

Cited by 19 publications

References 25 publications

Sorption of methanol, dimethyl carbonate, methyl acetate, and acetone vapors in CTA and PTMSP: General findings from the GAB Analysis

Sorption of methanol, dimethyl carbonate, methyl acetate, and acetone vapors in CTA and PTMSP: General findings from the GAB Analysis

The impact of ethylene glycol and hydrogen sulphide on the performance of cellulose triacetate membranes in natural gas sweetening

Partially Acetylated Cellulose Dissolved in Aqueous Solution: Physical Properties and Enzymatic Hydrolysis

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