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Preparation and Properties of EVOH/Carbon Nanotubes Composite Micro/Nanofibers

Author: XuGuanBiao
Tutor: XiaoRu
School: Donghua University
Course: Materials Processing Engineering
Keywords: Micro / nano fibers Carbon nanotubes EVOH Percolation behavior
CLC: TB383.1
Type: Master's thesis
Year: 2012
Downloads: 44
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Abstract


Carbon nanotubes (CNTs) due to its excellent physical and chemical properties and become a good inorganic filler pellets. Ethylene vinyl alcohol (EVOH) random copolymer has a high barrier, non-toxic, environmental protection and good workability, is a superior performance polymers. A lot of the preparation of nanofibers electrospinning method, interfacial polymerization, but can not meet the thermoplastic polymer nanofibers this paper, the melt spinning phase separation behavior successfully prepared different types of CNTs the EVOH / CNTs composite micro / nanofiber. First, the use of the blend of twin-screw extrusion prepared CNTs content of 0-12% different CNTs Type of EVOH / CNTs composite the masterbatch as the dispersed phase, biocompatible ester of cellulose acetate butyrate (CAB) as The base material, both fully blended by a twin screw melt-blending extrusion, by drawing with acetone and removal of the matrix phase, and to obtain a uniform size EVOH / CNTs composite micro / nano fibers. By transmission electron microscopy (TEM), scanning electron microscopy (SEM) were observed in the surface morphology of the three composite system of carbon nanotubes dispersed and micro / nano fibers, studies have shown that long multi-walled carbon nanotubes (LMWNTs) and aligned CNT (aMWNTs) having a good dispersibility in the EVOH matrix, carboxylated carbon nanotubes (COOH-MWNTs) in the matrix in a large agglomeration and poor dispersion. Good surface morphology of the EVOH / LMWNTs micro / nano-fibers, with increasing the carbon nanotube content in the fiber surface morphology, size and its distribution is basically unchanged, of EVOH / aMWNTs and EVOH / COOH-of MWNTs micro / nano surface of the fiber rough morphology with the increase of the carbon nanotube, the fibers of the latter also increases the size and its distribution. To study the crystallization of the composite system performance by X-ray diffraction (XRD) and differential scanning calorimetry (DSC), DSC studies show that the the EVOH / LMWNTs and the EVOH / aMWNTs micro / nano fiber crystallization temperature slightly compared to the pure EVOH fiber increased, while the melting temperature and the degree of crystallinity decreased. The crystallization temperature and melting temperature of the EVOH / COOH-MWNTs micro / nano fibers with the carbon nanotubes increased significantly decreased, when the carbon nanotube content of 6% degree of crystallinity maximum. XRD studies show that the adding of the carbon nanotubes makes of EVOH / LMWNTs and EVOH / aMWNTs, micro / nano fiber at 20 = 26 °, there will be an amorphous carbon, the characteristic diffraction crystal surface (020). Study the thermal stability of the composite system by thermogravimetric instrument (TG), the study showed that the adding of the carbon nanotubes significantly improves the thermal stability of the the of EVOH / LMWNTs and EVOH / aMWNTs micro / nano-fibers, but reduces the EVOH / COOH-MWNTs The thermal stability of the micro / nano-fiber with carbon nanotubes dispersed in the matrix, which are closely linked. However, the residual mass of the three systems with carbon nanotube to increase the non-linear growth. Visco-elastic and conductive percolation behavior through dynamic rheological testing and volume resistivity test composite system, research the the EVOH / LMWNTs and EVOH / aMWNTs composite with similar viscoelastic and conductive percolation phenomenon, viscoelastic percolation threshold and conductive percolation The threshold value is very close to, are located in the 8-10wt%, and the adding of the carbon nanotubes can be made of composite material decline in resistivity by 4-5 orders of magnitude. The volume resistivity of the EVOH / COOH-MWNTs composite material with carbon nanotubes increased substantially constant, which is the destruction of the conductive structure of the carbon nanotubes due-COOH added.

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