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Gu Z.,CAS Hefei Institutes of Physical Science | Zhang X.,CAS Hefei Institutes of Physical Science | Zhang X.,Anhui Hualing Cable Group Company Ltd | Bao C.,CAS Hefei Institutes of Physical Science | And 7 more authors.
Journal of Non-Crystalline Solids | Year: 2014

Ethylene-propylene-diene rubber (EPDM)/stearic acid (SA) composites with improved strength and high damping performance were prepared by blending. With increasing SA content, the damping and mechanical properties of EPDM both quickly increased and there existed a percolation threshold of SA loadings, respectively. By analyzing the viscoelastic properties and cross-linking process of EPDM composites, it could be thought that the two percolations were attributed to two different cross-linked networks caused by phase-change organic acid, respectively. The percolation of damping performance coincides with that of liquidlike-solidlike transition of EPDM molecular chains, which was due to the decreasing cross-linking density, caused by restricting the decomposition of vulcanizing agent by SA, and enhanced the mobility of EPDM chains. The mechanical percolation was mainly dependent on the formation of a physical rubber-filler network by increasing crystal SA, which behaved as a filler before phase-change happened. © 2014 Published by Elsevier B.V.


Xue M.,CAS Hefei Institutes of Physical Science | Zhang X.,CAS Hefei Institutes of Physical Science | Zhang X.,Anhui Hualing Cable Group Company Ltd | Gu Z.,CAS Hefei Institutes of Physical Science | And 4 more authors.
Journal of the Textile Institute | Year: 2014

Ethylene-propylene-diene monomer (EPDM) ultrafine fibers have been prepared by electrospinning method, with an average diameter of micron grade and fibrous structural morphology. The effects of experimental parameters, including the solution concentration, applied voltage, collection distance, and flow rate, were investigated carefully. It shows that the morphology and fiber diameter of electrospun EPDM fibers are greatly influenced by the process parameters. Fourier transform infrared, X-ray diffraction, and differential scanning calorimetry apparatuses were used to analyze the structural and thermal properties of the electrospun fiber mat, with EPDM cast film as a comparison. The results reveal that the electrospun fiber mat has a lower degree of crystallinity than its cast film. © 2013 © 2013 The Textile Institute.


Gu Z.,Chinese Academy of Sciences | Zhang X.,Chinese Academy of Sciences | Zhang X.,Anhui Hualing Cable Group Company Ltd | Bao C.,Chinese Academy of Sciences | And 3 more authors.
Journal of Macromolecular Science, Part B: Physics | Year: 2015

Dynamic mechanical experiments performed on ethylene-propylene-diene (EPDM) terpolymer, cross linked to different extents, evidenced three relaxation processes. Besides the glass transition (Tg) and the melting of the ethylene crystals formed in the ethylene-based EPDM, a new transition appeared at a temperature higher than the glass transition temperature (so-called tan δgh) and decreased dramatically in amplitude with increase in the degree of cure. The new transition (tan δgh) was also above the melting point. The viscoelastic properties of the rubber with various crosslinking degrees are described. Based on the behavior of tan δgh and the curing properties of EPDM, the tan δgh peak is primarily attributed to the motion of non-elastic network chains loosely attached to the three-dimensional network, including free chains. © 2015 Taylor & Francis Group, LLC.


Gu Z.,CAS Hefei Institutes of Physical Science | Zhang X.,CAS Hefei Institutes of Physical Science | Zhang X.,Anhui Hualing Cable Group Company Ltd | Ding X.,CAS Hefei Institutes of Physical Science | And 7 more authors.
Soft Matter | Year: 2014

This article studied the influence of silica (SiO2) particles on the crosslinked network and the molecular mobility of ethylene-propylene-diene (EPDM) rubber chains by dynamic mechanical analysis (DMA). When SiO2 fraction is lower than 8 phr, the chain segments that participate in the glass-rubber transition (α transition) decrease with increasing the SiO2 content, while the whole crosslinked network is almost unaffected by the presence of SiO2. When the SiO2 fraction increases to about 20 phr, there appears a new tanδ peak (α′ transition) above the α transition. This could be because the crosslinking reaction took place only on a small scale and the formed network became gradually incomplete when the content of the particles exceeded some critical value, and the α′ transition is attributed primarily to the motion of non-elastic network chains loosely attached to the three-dimensional network. However, at SiO2 loadings higher than 40 phr, the crosslinking density was kept basically constant. The α′ transition is hindered by a restriction of the chain mobility due to SiO2. The different changes of α′ transition depended on the two coupled effects of SiO2, including restricting the chain mobility and decreasing the crosslinking density. Correspondingly, with increasing the mobility of EPDM chains and SiO2-induced strengthening, the mechanical properties of EPDM composite are dramatically improved. With the addition of 20 phr of SiO2 in the EPDM, a 113% increase in the elongation at break, a 510% increase in the fracture energy, and a 283% increase in the tensile strength are achieved. © the Partner Organisations 2014.


Xue M.,CAS Hefei Institutes of Physical Science | Zhang X.,CAS Hefei Institutes of Physical Science | Zhang X.,Anhui Hualing Cable Group Company Ltd | Wu Z.,CAS Hefei Institutes of Physical Science | And 4 more authors.
Journal of Applied Polymer Science | Year: 2014

The aim of this work is to develop a halogen-free thermoplastic polyurethane (TPU) composite with significantly improved fire performance by using a highly commercial phosphorous-nitrogen containing intumescent flame retardant (P-N IFR). Based on the characterizations of thermogravimetric analysis and in situ Fourier transform infrared spectra, P-N IFR powder was proved a desired flame retardant for TPU in theory and the thermal degradation property of PU/PNIFR composites at elevated temperatures was investigated as well. Fire performance was evaluated by limiting oxygen index, underwriters laboratories 94 testing and char residue morphologies. Results showed that the addition of P-N IFR promotes the formation of char residues which were covered on the surface of polymer composites resulting in the improvement of thermal stability and flame retardancy. © 2013 Wiley Periodicals, Inc.

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