Rheological responses of fumed silica suspensions under steady and oscillatory shear

Yang, Hailin; Ruan, Jianming; Zou, Jianpeng; Wu, Qiong; Zhou, Zhiyong; Zhou, Zhi‐Hua

doi:10.1007/s11431-008-0283-6

“…From the literature, for fumed silica dispersions, it was explained that weak steric repulsive force and Brownian motion prevent further association of fumed silica aggregates at very low shear rates [73]. The viscosity of the suspension decreased by increasing shear rate because some of the agglomerations were disrupted and the orientation of fumed silica particles aligns with the direction of the shear flow [10,73,121].…”

Section: Discussionmentioning

confidence: 99%

An investigation of the mechanical and biological properties of nylon coated ultra-high-molecular-weight polyethylene

Firouzi¹

2023

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In spite of considerable improvements in the manufacturing of body armor using lightweight and high-strength fibres, demands for lighter and more flexible products capable of providing sufficient protection against various types of threats has not waned. Among high strength fibres, ultra high molecular weight polyethylene (UHMWPE) possesses superior mechanical and physical properties. Nevertheless, the use of UHMWPE fabric with a shear thickening fluid (STF) materials for the manufacture advanced liquid body armors has been unsuccessful as this polymer is inherently inert and cannot bond or readily interact with other materials. To address these challenges, this research thesis focused on the development of a new method to increase the performance of UHMWPE fibre/fabric for high impact applications and improve its capability to bond with silica-based STF materials. A novel coating technique was developed using a nylon solution with UHMWPE fibre which results in a strong interlocking mechanism and the creation of a uniform coating without adding extra thickness to the fibre. Standard penetration tests showed considerable improvement in puncture/stab resistance of a nylon coated UHMWPE fabric compared with the uncoated fabric (with equivalent areal density) in terms of energy absorption, which was also explained by the scanning electron microscope (SEM) images of ruptured areas. In order to further improve the penetration resistance of UHMWPE fabric, a dispersion of fumed silica particles in polyethylene glycol (PEG) was synthesized exclusively via a novel sequential ultrasonication technique to incorporate with a multilayer stack of UHMWPE fabric. A complete set of rheological measurements, zeta potential and SEM analysis were done to study the viscoelastic characteristics and tune the stability of the synthesized STF samples. Evidence of the improved adhesion of STF materials to UHMWPE fibres coated with nylon from the SEM images was observed. Finally, while the evidence of improved mechanical properties of nylon coated UHMWPE were provided (e.g. higher creep resistance and toughness), its potential application for the manufacturing of medical devices was also explored. As a result, from the preliminary cytotoxicity and osteolysis assessments, it was shown that the biological compatibility of UHMWPE was improved when it was coated with nylon.

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“…From the literature, for fumed silica dispersions, it was explained that weak steric repulsive force and Brownian motion prevent further association of fumed silica aggregates at very low shear rates [73]. The viscosity of the suspension decreased by increasing shear rate because some of the agglomerations were disrupted and the orientation of fumed silica particles aligns with the direction of the shear flow [10,73,121].…”

Section: Discussionmentioning

confidence: 99%

An investigation of the mechanical and biological properties of nylon coated ultra-high-molecular-weight polyethylene

Firouzi¹

2023

Preprint

0

View full text Add to dashboard Cite

In spite of considerable improvements in the manufacturing of body armor using lightweight and high-strength fibres, demands for lighter and more flexible products capable of providing sufficient protection against various types of threats has not waned. Among high strength fibres, ultra high molecular weight polyethylene (UHMWPE) possesses superior mechanical and physical properties. Nevertheless, the use of UHMWPE fabric with a shear thickening fluid (STF) materials for the manufacture advanced liquid body armors has been unsuccessful as this polymer is inherently inert and cannot bond or readily interact with other materials. To address these challenges, this research thesis focused on the development of a new method to increase the performance of UHMWPE fibre/fabric for high impact applications and improve its capability to bond with silica-based STF materials. A novel coating technique was developed using a nylon solution with UHMWPE fibre which results in a strong interlocking mechanism and the creation of a uniform coating without adding extra thickness to the fibre. Standard penetration tests showed considerable improvement in puncture/stab resistance of a nylon coated UHMWPE fabric compared with the uncoated fabric (with equivalent areal density) in terms of energy absorption, which was also explained by the scanning electron microscope (SEM) images of ruptured areas. In order to further improve the penetration resistance of UHMWPE fabric, a dispersion of fumed silica particles in polyethylene glycol (PEG) was synthesized exclusively via a novel sequential ultrasonication technique to incorporate with a multilayer stack of UHMWPE fabric. A complete set of rheological measurements, zeta potential and SEM analysis were done to study the viscoelastic characteristics and tune the stability of the synthesized STF samples. Evidence of the improved adhesion of STF materials to UHMWPE fibres coated with nylon from the SEM images was observed. Finally, while the evidence of improved mechanical properties of nylon coated UHMWPE were provided (e.g. higher creep resistance and toughness), its potential application for the manufacturing of medical devices was also explored. As a result, from the preliminary cytotoxicity and osteolysis assessments, it was shown that the biological compatibility of UHMWPE was improved when it was coated with nylon.

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“…The flow index n indicates the departure from Newton model and n = 1, n [ 1 and n \ 1 exhibit Newtonian, shear-thickening and shear-thinning behavior, respectively [25,26]. For n = 1, K becomes the dynamic viscosity g. Table 1 shows the values of the fitting parameters K and n, and the regression coefficient R 2 .…”

Section: Rheological Behavior and Spinnability Of The Precursor Solmentioning

confidence: 99%

Rheological behavior, molecular structure of precursor and evolution mechanism: zirconia fibers from polyaceticzirconium precursors

Liu

¹

,

Liu

²

,

Wang

³

et al. 2015

J Sol-Gel Sci Technol

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Polycrystalline zirconia fibers with dense surface and good flexibility were achieved from polyaceticzirconium (abbreviated as PEZ) precursor fibers followed by steam pretreatment and post-calcination. PEZ was synthesized via a one-pot solid-liquid reaction between basic zirconium carbonate and glacial acetic acid in methanol. Rheological behavior of the precursor sol with different concentrations was investigated, the power law model was used to describe the rheological behavior more accurately, and the relationship between the rheology and the spinnability of sol was discussed particularly. For the polymeric structure of PEZ, acetic acid was used as chelating agent and the carboxyl group was acted as a bidentate bridging ligand, which was speculated by FT-IR analysis. The effect of the pretreatment atmosphere on the evolution of the precursor fibers and the microstructure of the final fibers was discussed. The acetate group was removed in the form of molecules, and the final fibers preheated under steam atmosphere had better densification and flexibility than those were not. In addition, crystallization process, phase composition and thermal decomposition were investigated by XRD, Raman spectra and TG/DSC. Graphical Abstract The preheated atmosphere exerts an important influence on the densification and flexibility of zirconia fibers. Under steam atmosphere, acetate group in the precursor fibers is removed in the form of molecules and zirconia fibers sintered at 1050°C for 2 h have a dense surface. However, zirconia fibers not subjected to the steam pretreatment have a large number of voids on the surface due to the decomposition of the organics. Furthermore, the fibers preheated under steam atmosphere have better flexibility than those were not. Therefore, pretreatment under steam atmosphere is essential for the preparation of the dense and flexible fibers.

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Rheological responses of fumed silica suspensions under steady and oscillatory shear

Cited by 20 publications

References 19 publications

An investigation of the mechanical and biological properties of nylon coated ultra-high-molecular-weight polyethylene

An investigation of the mechanical and biological properties of nylon coated ultra-high-molecular-weight polyethylene

An investigation of the mechanical and biological properties of nylon coated ultra-high-molecular-weight polyethylene

Rheological behavior, molecular structure of precursor and evolution mechanism: zirconia fibers from polyaceticzirconium precursors

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