Meifang Zhu

Study on Phase‐Change Characteristics of PET‐PEG Copolymers

Polyethylene glycol (PEG) was selected as a phase‐change material (PCM) and the phase‐change fibers of its copolymers with polyethylene terephalate (PET), PET‐PEG, were successfully prepared by melt spinning. The PET‐PEG copolymers have solid‐solid phase change characteristics at 10–60°C without obvious liquid substance appearing, while PET/PEG blends will lose their phase‐change characteristics since the PEG of the blends may melt and leak under high temperature. By controlling the molecular weight and relavent proportion of PEG added, the phase‐change temperature range and the enthalpy can be adjusted.

Programmable responsive shaping behavior induced by visible multi-dimensional gradients of magnetic nanoparticles

Herein, we report a new ‘programmable’ responsive shaping behavior induced by the visible multi-dimensional gradient of magnetic nanoparticles (MNP): the materials exhibit different local curvatures and a sequence of responsive shapes during the responsive process; the sequence and the local curvature are accurately defined by ‘programmed instructions’—MNP gradients in the materials.

Poly(m‐Phenylene Isophthalamide) Ultrafine Fibers from an Ionic Liquid Solution by Dry‐Jet‐Wet‐Electrospinning

Ultrafine poly(m‐phenylene isophthalamide) (PMIA) fibers from PMIA solution in an ionic liquid via dry‐jet‐wet electrospinning technology are described. The morphology of the fibers with and without treatment in a coagulation water bath in the dry‐jet‐wet‐electrosinning process was observed by scanning electrical microscopy (SEM) and a high resolution optical microscope. The crystal structure of the fibers was analyzed by wide angle X‐ray diffraction (WAXD). The differences of morphologies and properties between the ultrafine fibers obtained by the electrospinning process and fibers from conventional wet‐spinning technology are discussed. The thermal properties of the ultrafine PMIA fibers were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).

Mechanism of the Formation of Concentric Ring-like Patterns on PHBV Spherulites

Abstract Polymers of the 3-hydroxybutyrate-co-3-hydroxyvalerate type are ideal systems for the study of spherulite morphology. The growth of spherulites was studied using polarizing microscopy with heat-stage and scanning electron microscopy (SEM). Some concentric ring features on poly(3-hydroxybutyrate-co-3-hydroxyvalerate) PHBV spherulite were observed. The SEM photos proved that the concentric rings occur on the surface of spherulite. And its a “Z”-shape feature, the outer ring is higher than the inner. The factors that influence the phenomenon include the temperature, the thickness of film, and the radius of the spherulite, etc. The possible mechanism of this phenomenon is given. It is postulated that the concentric rings are formed by the change on physical parameters when crystallizing.

One‐Dimensional Magnetic Composite of Polypyrrole‐Containing Carbon Nanotubes/Ni0.75Zn0.25Fe2O4

A novel one‐dimensional electromagnetic nanocomposite of polypyrrole (PPY) containing carbon nanotubes (CNTs)/Ni0.75Zn0.25Fe2O4 was synthesized by an in‐situ polymerization method. The composite was characterized by x‐ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and Fourier transform infrared. The XRD results confirmed that PPY, CNTs, and Ni0.75Zn0.25Fe2O4 coexisted in the composite. The TEM and HRTEM results indicated that PPY coated the surface of the CNTs/Ni0.75Zn0.25Fe2O4 with a thickness of 15–30 nm. The lattice spacings, according to the first main peak of the CNTs, Ni0.75Zn0.25Fe2O4, and PPY, was about 0.34 nm, 0.25 nm, and 0.42 nm, respectively. The FTIR result also indicated that the PPY formed in the composite. A test of magnetic properties indicated that the composite was ferromagnetic with the saturated magnetization of 12.86 electromagnetic units (emu)/g, and the coercive of 127.18 Oersted (Oe).