A novel multiwalled carbon nanotube/polypropylene (CNT/PP) conductive fibrous membrane with fiber diameter of 1–3 μm was fabricated by melt electrospinning. To improve the dispersibility of CNT and enhance the spinnability of PP fibers, CNTs were first mixed with small amounts of paraffin liquid (PL) and then melt-blended with PP for melt electrospinning. The morphology of fibrous membranes and the orientation of CNTs in PP fibers were observed via scanning and transmission electron microscopy (SEM and TEM). The effect of PL and CNTs on crystallization behavior of PP was studied by differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Tensile test and impedance analysis were performed to investigate the mechanical and electrical properties of the fibrous membranes. The results indicated that CNT has a distinct nucleating effect on PP, and the addition of PL can improve the spinnability of the CNT/PP compound remarkably. This novel conductive fibrous membrane fabricated by melt electrospinning exhibits improved tensile strength and modulus, good electric conductivity, and enhanced dielectric constant and hydrophobicity.

Through a combination of Y zeolite precursors and the pH-adjusting method, bimodal aluminosilicates (denoted as LFs) with strong acidity and excellent hydrothermal stability were synthesized. The hydrothermal stability of the resulting aluminosilicates was improved greatly by taking advantage of Y zeolite precursors (the retaining ratio of the total surface area was 33% after hydrothermal treatment in 100% water vapor at 800 °C for 15 h). When the mesostructure was basically formed in the first crystallization, the pH of the reaction system was adjusted from strong acid to neutral, followed by the second hydrothermal crystallization, during which a large amount of Al could be introduced into the mesophases. XRF and Al NMR showed that LFs possessed a high alumina loading (with SiO 2 /Al 2 O 3 molar ratio of 24.4) and most of the Al was tetrahydrally coordinated. NH 3 -TPD results indicated that the total amount of acid sites increased 12.9 times compared with that of ZF (without pH adjustment). The resulting aluminosilicates with simultaneously enhanced acidity and hydrothermal stability showed superior catalytic properties when used in heavy crude oil catalytic cracking. Our achievements have developed a general synthetic route of bimodal aluminosilicates with strong acidity and excellent hydrothermal stability.

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High-performance copolyimide (co-PI) fibers were prepared via the wet spinning process of co-polyamide acid precursors based on 3,3 0 ,4,4 0 -biphenyldianhydride (BPDA) and a mixture of three diamines namely p-phenylene diamine (p-PDA), 2-(4-aminophenyl)-5-aminobenzimidazole (BIA), and 4,4 0 -oxidianiline (ODA), followed by drawing and imidization at high temperatures. Effects of the ODA and BIA contents on the molecular packing, morphology, hydrogen-bonding interactions, mechanical and thermal properties of the prepared fibers were investigated. The mechanical properties of the co-PI fibers were improved with the addition of ODA and BIA, and they reached the optimum tensile strength of 2.7 GPa and modulus of 94.3 GPa. Wide-angle X-ray diffraction results (WAXD) showed that the co-PI fibers exhibited highly oriented structure along the fiber direction with low degree of lateral packing orders in the transverse direction. Two-dimensional small-angle X-ray scattering (2D-SAXS) revealed that the incorporation of ODA resulted in the reduction in radius, length, misorientation, and internal surface roughness of the microvoids in the fibers. Fourier transform infrared (FTIR) results indicated that hydrogen-bonding formed between the BIA and cyclic imide units effectively strengthened the intermolecular interactions. The co-PI fibers exhibited excellent thermal and thermal-oxidative stability, with a 5%-weight-loss temperature of 5788C under N 2 and 5728C in air. POLYM. ENG. SCI., 55:2615-2625, 2015.