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Polymer-nanofiller prepared by high-energy ball milling and high velocity cold compaction
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.ORCID iD: 0000-0001-5760-3919
2008 (English)In: Polymer Composites, ISSN 0272-8397, E-ISSN 1548-0569, Vol. 29, no 3, 252-261 p.Article in journal (Refereed) Published
Abstract [en]

High-energy ball milling using comilling in a solid state by low-temperature mechanical alloying to prepare nickel-ferrite (NiFe2O4) nanopowders and ultrafine poly(methyl methacrylate) (PMMA), dispersing nanoparticles in a polymer matrix, and a uniaxial high-velocity cold compaction process using a cylindrical, hardened steel die and a new technique with relaxation assists have been studied. The focus has been on the particle size distributions of the nanocomposite powder during the milling and on the surface morphology of the nanocomposite-compacted materials after compaction with and without relaxation assists. Experimental results for different milling systems are presented showing the effects of milling time and material ratio. It was found that a longer mixing time give a higher degree of dispersion of the nanopowder on the PMMA particle surfaces. Furthermore, with increasing content of NiFe2O4 nanopowder, the reduction of the particle size was more effective. Different postcompacting profiles, i.e. different energy distributions between the upper and lower parts of the compacted powder bed, lead to different movements of the various particles and particle layers. Uniformity, homogeneity, and densification on the surfaces in the compacted powder are influenced by the postcompacting magnitude and direction. It was found that the relaxation assist device leads to an improvement in the polymer powder compaction process by reducing the expansion of the compacted volume and by reducing the different opposite velocities, giving the compacted composite bed a more homogeneous opposite velocity during the decompacting stage and reducing the delay time between the successive pressure waves.

Place, publisher, year, edition, pages
2008. Vol. 29, no 3, 252-261 p.
Keyword [en]
LAYERED SILICATE NANOCOMPOSITES; COMPOSITE; POLYPROPYLENE; CONDUCTIVITY; EXTRUSION; POWDERS
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:kth:diva-6229DOI: 10.1002/pc.20353ISI: 000253401700003Scopus ID: 2-s2.0-41449115349OAI: oai:DiVA.org:kth-6229DiVA: diva2:10878
Note

QC 20100630

Available from: 2006-10-06 Created: 2006-10-06 Last updated: 2017-12-14Bibliographically approved
In thesis
1. Novel Technique to Improve High-Velocity Cold Compaction: Processing of Polymer Powders and Polymer-Based Nanocomposite High Performance Components
Open this publication in new window or tab >>Novel Technique to Improve High-Velocity Cold Compaction: Processing of Polymer Powders and Polymer-Based Nanocomposite High Performance Components
2006 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Compaction of polymer powders and polymer-based nanocomposites by uniaxial high-velocity cold compaction (HVC), by high-energy ball milling (HEBM) and using a novel technique, relaxation assists, was investigated with a focus on the process parameters, the compactibility characteristics, surface morphology and friction. The basic phenomena associated with HVC are explained and the general energy principle is introduced to explain the pull-out phenomenon, springback gradient, delay time, relative time of the pressure wave, and stick-slip phenomenon during the compaction process. Experimental results for different compaction profiles, different particle size distributions and different milling system for polymer-based nanocomposite are presented, showing the effect of varying the process parameters on the compacted material; the compactibility in the compacted bed, the uniformity of the compacted surface, the pull-out phenomenon, the springback gradient, the stick-slip phenomenon and the homogeneity of the dispersions of nanoparticles in the polymer powders in the solid state. It was found that the high-velocity compaction process is an interruption process and that the opposite velocity and pressure loss during the compaction process have a major influence on the quality of the compacted material. The relaxation assist device is a novel technique that has been successfully developed to improve the compaction process. The relaxation assists are parts of the piston and they are regarded as projectile supports. They are constructed of the same material as the piston, and the diameters are the same but the lengths are different. The relaxation assist device leads to an improvement in the compaction of powders, polymer powders and polymer-based nanocomposites by giving a more homogeneous opposite velocity and a better locking of the powder bed in the compacted form during the compaction process with less change in dimensions in the case of both homogeneous and heterogeneous materials. If the movement of the particles is restricted the powder bed attains a higher density and the total elastic springback is minimized. In addition, there is a more homogeneous dispersion of nanoparticles in the case of a heterogeneous material. A much better transfer of the pressure through the powder bed and a smaller loss of pressure lead to a more homogenous stick-slip of the particles and a higher sliding coefficient due to the overall friction during the compaction process.

Place, publisher, year, edition, pages
Stockholm: KTH, 2006
Series
Trita-FPT-Report, ISSN 1652-2443 ; 2006:31
Keyword
polymer powders, nanocomposites, high-velocity compaction, high-energy ball milling
National Category
Production Engineering, Human Work Science and Ergonomics
Identifiers
urn:nbn:se:kth:diva-4133 (URN)91-7178-459-4 (ISBN)
Public defence
2006-11-03, E2, Lindstedsvägen 3, Stockholm, 10:15
Opponent
Supervisors
Note
QC 20100630Available from: 2006-10-06 Created: 2006-10-06 Last updated: 2010-06-30Bibliographically approved

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Publisher's full textScopushttp://www3.interscience.wiley.com/cgi-bin/jhome/107639242

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Kari, Leif

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