Effect of comonomers on melt processability of polyacrylonitrile

Rangarajan, Pratima; Yang, Jinn‐Shyong; Bhanu, V. A.; Godshall, D.; McGrath, James E.; Wilkes, Garth L.; Baird, Donald G.

doi:10.1002/app.10655

Cited by 76 publications

(63 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previously, the time dependence of * was used to quantify the melt stability of the material. 5 However, copolymers for which minimal increases in * were observed (over the measurement time) became intractable during monofilament extrusion through a capillary rheometer. 13 It was believed that measuring as a function of time would more closely mimic melt extrusion, in which a high degree of mixing introduces the reactive nitrile groups of the polymer chains to each other.…”

Section: Steady Shear Viscositymentioning

confidence: 99%

“…Extensive efforts have been documented by Bhanu et al 7,8 and Rangarajan et al, 5,9 which had the goal of establishing a suitable polymerization technique, copolymer composition, comonomer types, and molecular weight to produce melt spinnable acrylic precursors that can be processed in the range of 200 -220°C. These studies focused largely on the use of suitable comonomers (primarily MA) in the range of 10 to 15 mol % to disrupt the long range order and modestly reduce the T g of AN copolymers, affording melt stability.…”

Section: Introductionmentioning

confidence: 99%

“…5 Melt spinning would also reduce costs by providing 100% solids throughput on a per pound basis compared to the 7-30 wt. % obtained from solution processing.…”

Section: Introductionmentioning

confidence: 99%

“…4 However, the prohibitive cost of carbon fiber production has somewhat limited their usage. 5 The rapid crosslinking reaction that can occur concurrently with the stabilization step requires that acrylonitrile (AN) copolymer precursor fibers be solution processed in the presence of toxic, environmentally unfriendly organic solvents, commonly including dimethyl formamide (DMF) and dimethylacetamide (DMAC). 3 These polar organic solvents are usually used in the range of 70 -93 wt % solvent (7-30 wt % solids) to permit processing at temperatures well below the onset of the crosslinking reaction.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Shear rheological properties of acrylic copolymers and terpolymers suitable for potentially melt processable carbon fiber precursors

Bortner

Bhanu

McGrath

et al. 2004

J of Applied Polymer Sci

View full text Add to dashboard Cite

ABSTRACT:In an effort to generate melt processable polyacrylonitrile (PAN) precursor fibers suitable for conversion to carbon fibers, an acrylonitrile/methyl acrylate (AN/ MA) copolymer and two acrylonitrile/methyl acrylate/acryloyl benzophenone (AN/MA/ABP) terpolymers were synthesized at molar ratios of 85/15 and 85/14/1, respectively. The termonomer (ABP) was incorporated to accelerate crosslinking via UV irradiation, which serves to prevent relaxation of orientation and flow as the temperature of the fiber is raised during thermooxidative stabilization. Two molecular weights of the terpolymer and one molecular weight of the copolymer were studied to determine the effect of the termonomer, and the effect of molecular weight (MW), on the steady shear viscosity () and magnitude of the complex viscosity ( * ). A higher rate of increase of as a function of time was observed for the high MW terpolymer relative to that of the copolymer over the temperature range used. Using a temperature sweep and monitoring levels of * , a minimum was observed at lower temperatures for both terpolymers. These results suggest that copolymerization with ABP significantly increased the thermally induced kinetics of crosslinking. Comparison of the and * data for the low and high MW terpolymers suggested that molecular weight also significantly reduced the melt stability (increased the kinetics of crosslinking). A chemorhelogical correlation was then used to quantify the effects of the termonomer and of molecular weight on the kinetics of crosslinking of the AN terpolymers.

show abstract

Section: Steady Shear Viscositymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…5 Melt spinning would also reduce costs by providing 100% solids throughput on a per pound basis compared to the 7-30 wt. % obtained from solution processing.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Shear rheological properties of acrylic copolymers and terpolymers suitable for potentially melt processable carbon fiber precursors

Bortner

Bhanu

McGrath

et al. 2004

J of Applied Polymer Sci

View full text Add to dashboard Cite

show abstract

“…

ABSTRACT: Novel polyacrylonitrile (PAN)-co-poly(hydroxyethyl acrylate) (PHEA) copolymers at three different compositions (8,12, and 16 mol % PHEA) and their homopolymers were synthesized systematically by emulsion polymerization. Their chemical structures and compositions were elucidated by Fourier transform infrared, 1 H-NMR, and 13 C-NMR spectroscopy.

…”

mentioning

confidence: 99%

Tailoring the swelling and glass‐transition temperature of acrylonitrile/hydroxyethyl acrylate copolymers

Aran

Sankır

Vargün

et al. 2009

J of Applied Polymer Sci

View full text Add to dashboard Cite

Novel polyacrylonitrile (PAN)-co-poly(hydroxyethyl acrylate) (PHEA) copolymers at three different compositions (8,12, and 16 mol % PHEA) and their homopolymers were synthesized systematically by emulsion polymerization. Their chemical structures and compositions were elucidated by Fourier transform infrared, 1 H-NMR, and 13 C-NMR spectroscopy. Intrinsic viscosity measurements revealed that the molecular weights of the copolymers were quite enough to form ductile films. The influence of the molar fraction of hydroxyethyl acrylate on the glass-transition temperature (T g ) and mechanical properties was demonstrated by differential scanning calorimetry and tensile test results, respectively. Additionally, thermogravimetric analysis of copolymers was performed to investigate the degradation mechanism. The swelling behaviors and densities of the free-standing copolymer films were also evaluated. This study showed that one can tailor the hydrogel properties, mechanical properties, and T g 's of copolymers by changing the monomer feed ratios. On the basis of our findings, PAN-co-PHEA copolymer films could be useful for various biomaterial applications requiring good mechanical properties, such as ophthalmic and tissue engineering and also drug and hormone delivery.

show abstract

Switchable Polyacrylonitrile‐Copolymer for Melt‐Processing and Thermal Carbonization—3D Printing of Carbon Supercapacitor Electrodes with High Capacitance

2022

View full text Add to dashboard Cite

allowing fast charge-discharge kinetics, long cycling stability, and high capacitance. [1][2][3][4] Typically, such carbon electrodes are produced from active carbon powders. [5] The required structural integrity of the electrode can only be achieved by mixing the active carbon powder with binders; however, these binders are often electrochemically inert and decrease the overall performance of the electrodes by blocking the surface and porosity of the active material. To produce electrodes without binder, carbon fiber non-wovens present ideal materials for components in fuel cells, batteries, and supercapacitors. [5][6][7][8][9][10][11] The most widely used precursor for carbon fibers and materials is polyacrylonitrile (PAN). [12] PAN can be converted into carbon materials in a two-step thermal conversion process. The first step is called stabilization, in which the nitrile groups engage in mostly intramolecular cyclization reactions, forming polymer ribbons. Stabilization is conducted in an oxidative atmosphere between 200 and 300 °C. [13][14][15] Strong dipolar interactions between the nitrile groups entail a high melting temperature T m , well above the activation energy for the cyclization reaction-or stabilization. The second step is the carbonization, in which the polymer ribbons fuse to graphitic domains. Carbonization is conducted in an inert atmosphere above 1000 °C. [13,16,17] Because of its sensitivity towards high temperatures-with potential for thermal run-away, due to the exothermic nature of the stabilization reaction-PAN is typically processed from solution.However, solution processing limits the final architectures of the desired carbon materials to fibers and films. [18][19][20] Fiber spinning and film formation processes are energy consuming and costly, as they require large amounts of solvents, which on an industrial scale have to be recovered and eventually disposed of. [21][22][23][24] A much more economic manufacturing approach would be to process PAN from its melt. [17,25,26] This strategy would enable 3D printing techniques such as polymer extrusion-based additive manufacturing (EAM) with full freedom-ofdesign, expanding the possible shapes of carbon materials from 1D fibers and 2D films to monolithic 3D workpieces. To our advantage, EAM would allow fully automated shaping of PAN into complex structures. EAM is scalable, fast, solvent-free, and Polyacrylonitrile (PAN) represents the most widely used precursor for carbon fibers and carbon materials. Carbon materials stand out with their high mechanical performance, but they also show excellent electrical conductivity and high surface area. These properties render carbon materials suitable as electrode material for fuel cells, batteries, and supercapacitors. However, PAN has to be processed from solution before being thermally converted to carbon, limiting its final format to fibers, films, and non-wovens. Here, a PAN-copolymer with an intrinsic plasticizer is presented to reduce the melting temperature and avoid undesired entering of the t...

show abstract

Effect of comonomers on melt processability of polyacrylonitrile

Cited by 76 publications

References 19 publications

Shear rheological properties of acrylic copolymers and terpolymers suitable for potentially melt processable carbon fiber precursors

Shear rheological properties of acrylic copolymers and terpolymers suitable for potentially melt processable carbon fiber precursors

Tailoring the swelling and glass‐transition temperature of acrylonitrile/hydroxyethyl acrylate copolymers

Switchable Polyacrylonitrile‐Copolymer for Melt‐Processing and Thermal Carbonization—3D Printing of Carbon Supercapacitor Electrodes with High Capacitance

Contact Info

Product

Resources

About