Caixia Jia

Preparation and low-frequency microwave-absorbing properties of MWCNTs/Co–Ni/Fe3O4 hybrid material

MWCNTs/Co–Ni/Fe3O4 hybrid material has been successfully prepared by electroless plating and coprecipitation method, which is applied to the low-frequency microwave absorption. Their surface morphology, structure, magnetism and electromagnetic properties in the low-frequency range of 1–4GHz were characterized by field-emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and vector network analyzer. Results indicated that magnetic Co–Ni/Fe3O4 particles were attached on the surface of multi-walled carbon nanotubes successfully. The saturation magnetization of MWCNTs/Co–Ni/Fe3O4 hybrid materials was 68.6emu/g and the coercivity is 17.9 Oe. The electromagnetic and microwave absorbing properties analysis in the low-frequency range of 1–4GHz indicated that the hybrid material exhibited excellent magnetic loss and the maximum reflection loss could reach −13.57dB at 1.51GHz with 1.05GHz bandwidth below −5dB.

The effects of thermally reversible agents on PVC stability properties

One kind of thermally reversible cross-linking agents for improving PVC thermally stability was synthesized. The chemical structure and thermally reversible characteristics of cross-linking agents were investigated by FTIR and DSC analysis, respectively. FTIR results confirmed that the cyclopentadienyl barium mercaptides ((CPD-C2H4S)2Ba) were successfully synthesized. DSC results showed it has thermally reversible characteristics and the depolymerization temperature was between 170 ?C and 205 ?C. The effects of cross-linking reaction time on gel content of Poly(vinyl chloride) compounds was evaluated. The gel content value arrived at 42% after being cross-linked for 25 min at 180 C. The static thermally stability measurement proved that the thermally stability of PVC compounds was improved.