Using a jacket-type heat exchanger to control the solution temperature, the electrospinning of polyacrylonitrile/dimethylformamide (PAN/DMF) solutions with various concentrations was carried out at temperatures ranging from ambient to 88.7 °C. The purpose of this is to investigate the temperature effect on the cone/jet/fiber morphologies that developed. By varying the solution temperature, the chain entanglement status existing in the solution (which is the prerequisite condition for preparing uniform fibers) remained intact. However, the solution properties were significantly altered, thereby giving rise to a feasible route to manipulate the as-spun fiber diameter. By increasing the solution temperature, it was found that the viscosity (η o ) and surface tension (γ) of the PAN/DMF solutions were decreased, but the solution conductivity (κ) was increased; all these trends favored the development of thinner electrospun PAN fibers at high electrospinning temperatures. For instance, with the 6 wt % solutions, PAN fibers with a diameter of 65-85 nm were readily prepared by electrospinning at 88.7 °C, whereas larger fibers with a diameter of 190-240 nm were frequently obtained at room temperature. The temperature dependence of η o , γ, and κ followed the Arrhenius equation, and the corresponding activation energies were composition dependent and found to be ca. 15-28, ∼10 and ∼3.7 kJ/mol, respectively. Hightemperature electrospinning eventually produced PAN fibers with less crystallinity but higher chain orientation as revealed by the wide-angle X-ray diffraction and birefringence measurements. Moreover, the scaling law for the viscosity dependence of fiber diameter, d f , was also altered from d f ) 14.8η o 0.52 (unit: d f in nm and η o in cP) at room temperature to d f ) 3.0η o 0.74 at 88.7 °C, suggesting that high-temperature electrospinning was an effective method to produce ultrathin fibers.

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This study evaluated the usefulness of bioceramic materials (ceramic materials that emit high-performance far-infrared (FIR) rays), processed into fabrics using a traditional manufacturing melt spinning method. Numerous measurements were designed to test the biological functions of 1% bioceramic fabrics. These included physical induction of intracellular nitric oxide (NO) in NIH 3T3 cells (mouse fibroblasts), the effects on cell viability in osteoblastic cells (MC3T3-E1) under hydrogen peroxide-mediated oxidative stress, and the effects on lipopolysaccharide (LPS)-induced cyclo-oxygenase-2 (COX-2) and prostaglandin E2 (PGE2) production in a chondrosarcoma (SW1353) cell line. When compared to the control group, the bioceramic fabrics were capable of inducing further intracellular NO production using NIH 3T3 cells, and maintaining increased viability and against cell intoxication of osteoblastic cells by suppressing cell release of lactate dehydrogenase (LDH) under oxidative stress. In addition, it was found to suppress LPS-induced COX-2 production more significantly in a SW1353 cell line. These processes represent the biomolecular changes occurring during promotion of decline in aging, prevention of osteoporosis, and prevention of inflammatory processes within the human body. Therefore, these bioceramic fabrics are likely to fulfill their claims of having health-promoting benefits.