Wet spinning of liquid crystalline solutions of cellulose acetate butyrate and cellulose triacetate

Bheda, Jayant; Fellers, John F.; White, James L.

doi:10.1002/app.1981.070261142

Cited by 27 publications

(6 citation statements)

References 18 publications

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“…26,2165-2180 (1981 17 Our interests have been directed toward thermotropic liquid crystalline polymers because solvents may be eliminated, thus avoiding problems of solvent toxicity and recovery and the vagaries of void structures formed during coagulation. The only known thermotropic polymer liquid crystals are aromatic polyesters.lOJ1 It is shown in this report that some hydroxypropylcelluloses (Fig.…”

Section: Introductionmentioning

confidence: 99%

Hydroxypropylcellulose, a thermotropic liquid crystal: Characteristics and structure development in continuous extrusion and melt spinning

Shimamura¹,

White²,

Fellers³

1981

J of Applied Polymer Sci

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138

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SynopsisHot-stage polarized light microscopy suggests that bulk hydroxypropylcellulose (Hercules Klucel E) is a cholesteric liquid crystal. Rheological measurements indicate this system exhibits shear viscosities similar to those of polyolefin melts except that it has a yield value comparable to suspensions. Birefringent characteristics were observed in shear flow between glass slides. No relaxation of birefringence is observed following flow. Extruded filaments (without applied take-up tensions) show high levels of birefringence and significant orientations from WAXS measurements. These have skin-core structures with highly oriented outer layers which are caused by the flow patterns in the reservoir and die preceding the extrudate. In the case of melt-spun filaments, where tensile elongation occurs, a highly oriented structure of uniform cross section is found. INTRODUCTIONThe history of the development of plastics and fibers from cellulose derivatives dates back more than a ~e n t u r y . l -~ The decline in commercial importance of cellulosics from 1930 coincides with the growth of polymer physical chemistry and structural characterization techniques. Cellulose derivatives have not received the detailed study given to polyolefins, polydienes, etc. Liquid crystalline structure in polymer systems was first observed in concentrated solutions of polypeptides by Courtaulds investigator^^,^ in the mid-1950s. Similar structures were found in solutions of para-linked aromatic p~l y a m i d e s~~ and other relatively rigid aromatic polycondensates.lOJ1 Somewhat surprisingly, liquid crystalline structures were observed in hydroxypropylcellulose-water solutions by Werbowyj and Gray12J3 and othersg shortly thereafter. Liquid crystalline characteristics were reported in a wide range of cellulose derivative solutions by Panar and Will~ox.~* These observations were extended to other cellulose derivatives by Aharoni15 and Bheda, Fellers, and White,16J7 The development of high levels of birefringence and orientation during flow of solutions of hydroxypropylcellulose has been described by Onogi, White, and Fellers18 and Asada et al.19 Similar studies for cellulose acetate butyrate solutions have recently been reported by Bheda et al.17 This report concerns our efforts to study structure development in processing of liquid crystalline cellulose derivatives. The first investigations in this direction were reported by Panar and W i l l~o x~~ in a patent application. More recently, wet spinning of liquid crystalline cellulose acetate butyrate and cellulose tricetate * Permanent address: Institute of Chemical Research, Kyoto University, Uji, Kyoto, Japan.Journal of Applied Polymer Science, Vol. 26,2165-2180 (1981 17 Our interests have been directed toward thermotropic liquid crystalline polymers because solvents may be eliminated, thus avoiding problems of solvent toxicity and recovery and the vagaries of void structures formed during coagulation. The only known thermotropic polymer liquid crystals are aromatic polyesters.lOJ1 I...

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Section: Introductionmentioning

confidence: 99%

Hydroxypropylcellulose, a thermotropic liquid crystal: Characteristics and structure development in continuous extrusion and melt spinning

Shimamura¹,

White²,

Fellers³

1981

J of Applied Polymer Sci

Self Cite

138

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“…has inspired various research teams to both search for new liquid crystalline polymer systems7-18 and investigate their structure in the quiescent state14J7J9,20 and in f l~~.~~~~~-~ This has, in turn, led to continuing efforts in various industrial c o n c e r n~~-~~J~ and our own labo-ratories16. 26 to develop new fiber spinning processes based on a range of liquid crystalline polymer fluids.…”

Section: Introductionmentioning

confidence: 99%

Process for the formation of biaxially oriented films of poly(p‐phenylene terephthalamide) from liquid crystalline solutions

Flood¹,

White²,

Fellers³

1982

J of Applied Polymer Sci

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SynopsisA new process for making equal biaxially oriented films from liquid crystalline solutions of' poly(p-phenylene terephthalamide) (PPD-T) is described. The process involves extruding solutions of PPD-T/HzSO* through an annular die and over an oil-coated mandrel into a coagulation bath. The films were studied using wide angle X-ray diffraction (WAXS) and scanning electron microscopy (SEM). Tensile stress-strain properties were obtained on samples cut at various directions in the plane of the film. Biaxially oriented films which possess equal properties in the various directions in the plane of the film were produced. Moduli of 2.3 X lo9 Pa and tensile strengths of 9.6 X lo7Pa were obtained in the plane of the film. Films with unequal biaxial orientation were also produced. These tend to have higher modulus/tensile strength in the direction of major orientation, the machine direction (up to 8.3 X lo9 Pa/2.5 X 10s Pa), but become brittle in the transverse direction.

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“…All four cellulose ester samples exhibit an increase in viscosity with increasing concentration up to a maximum before decreasing with further increase in concentration (i.e., after Vp c ). Such an anomalous viscosity behavior is typical for liquid crystalline solutions, and this has been shown earlier for cellulose acetate (22,24), ethyl cellulose (25), hydroxypropyl cellulose (24,26), cellulose triacetate (27), and cellulose acetate butyrate (12,28). This change in viscosity is due to a change in the structure of the solutions.…”

Section: Resultsmentioning

confidence: 80%

Cellulose-Based Fibers from Liquid Crystalline Solutions

Davé

1992

Viscoelasticity of Biomaterials

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Solutions of cellulose esters with different concentrations in dimethyl acetamide (DMAc) and with different types of substituents, but with nearly constant total degree of substitution and constant molecular weights, were studied in relation to their liquid crystalline solution behavior. Observations made by dynamic mechanical spectrometry and by cross-polarized optical microscopy revealed classical liquid crystalline behavior for all solutions. Critical polymer concentration levels (Vpc) were observed for all cellulose esters, and these were found to vary with substitution pattern. Vpc is highest for cellulose acetate and lowest for the cellulose acetate butyrate with maximum degree of butyration. This is opposite to expected behavior based on the classical model by Flory, which predicts an increase in Vpc with decreasing aspect ratio. Cellulose ester solutions are viscoelastic in nature.Rigid rod-like polymers are recognized for their ability to form anisotropic liquid crystalline solutions (1,2). For rod-like species, the classical Flory equation of:relates the critical volume fraction, Vp c , of the polymer in solution to the appearance of a stable anisotropic phase; where X is the aspect ratio (L/d) of the polymer; L is the contour length; and d is the average diameter of the polymer chain. Cellulose is a linear homopolymer of ^-linked 1,4-anhydroglucose units. Liquid crystalline solution behavior has been observed with many cellulose and cellulose derivatives (3). Flory is credited with first commenting on the possibility of mesophase formation in cellulosic polymers (4). The most important parameter controlling the formar tion of a liquid crystalline phase appears to be chain stiffness for cellulose 0097-6156/92/0489-0144$06.50A)

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Wet spinning of liquid crystalline solutions of cellulose acetate butyrate and cellulose triacetate

Cited by 27 publications

References 18 publications

Hydroxypropylcellulose, a thermotropic liquid crystal: Characteristics and structure development in continuous extrusion and melt spinning

Hydroxypropylcellulose, a thermotropic liquid crystal: Characteristics and structure development in continuous extrusion and melt spinning

Process for the formation of biaxially oriented films of poly(p‐phenylene terephthalamide) from liquid crystalline solutions

Cellulose-Based Fibers from Liquid Crystalline Solutions

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