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

Abstract

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.

Effects of cross-linking methods for polyethylene-based carbon fibers: review

“…To establish CFs in the mass market, the price of CF precursors has to be significantly reduced [10,20,[23][24][25][30][31][32][33][34][35][36][37][38][39][40]. The lowest priced CF precursors primarily consist of polyethylene (PE) [41], lignin [33], and cellulose [42].…”

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

“…For example, the emulsion polymerization of AN and methyl acrylate with an acid stabilizer was largely studied by McGrath and coworkers. [12][13][14][15] However, none of the previous studies used HEA comonomer in the copolymerization of PAN to obtain copolymers with varied glass-transition temperatures (T g 's) and hydrophilicities.…”

“…TGA also revealed that copolymer series were thermooxidatively stable up to 330 C, which is high enough for many applications. 10,11,15 For mechanical tests, three samples for all of the compositions were prepared, and all samples were subjected to a progressively increasing tensile force until they fractured. The averages of the elastic modulus (E), ultimate tensile strength (UTS), and elongation at break (EAB) for these three samples for different compositions of PAN-PHEA copolymer films are given in Table III.…”

Fabrication, structures, and properties of acrylonitrile/methyl acrylate copolymers and copolymers containing microencapsulated phase change materials

“…The key step for realizing melting process PAN-based polymer is to lower the melting point or enhance the decomposition temperature. [6][7][8] Methyl acrylate (MA) comonomers possess better flexibility, so the incorporation of MA will help to weaken the dipole-dipole interaction. 7 In this article, we incorporate microcapsules into AN/MA copolymer matrix at the step of polymerization.…”

“…The increase of the MA molar ratio pushes the exothermic temperature to the higher side and meanwhile depresses the melting point. [6][7][8] It is attributed to the cyclization more difficultly with increasing the MA molar ratio. This exothermic peak is primarily consistent with cyclization, the formation of ladder structure.…”