• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 1
  • 1
  • Tagged with
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Modification of fly ash colour from grey black to near white and incoporation of fly ash in polypropylene polymer

Zaeni, Akhmad, Materials Science & Engineering, Faculty of Science, UNSW January 2009 (has links)
Particulate filled polymer composites are gaining growing acceptance in the commodity industry because the properties can be adjusted according to the industry's requirements. As particulate filler, fly ash is ready to compete with other particular fillers in polymer composites industries. Although fly ash is a cheap material but the fact that fly ash is grey-black in colour, limits the application of fly ash only to product where colour is not important. As such, a method was needed to be developed to increase the whiteness of fly ash without reducing the advantages of it as a cheap material. In this research, twelve commercially provided fly ash samples from Australian thermal power stations were investigated with respect to composition. Seven of them were thermally modified and further investigated and characterized with respect to colour, size, size distribution, and density. Of these seven fly ashes a particular grade was modified to a whiteness of 93.3 in L*a*b* scale (using barium sulfate as standard), without changing other inherent properties such as particle size and density. By comparison L*a*b* value for Omy carb 20, based on calcium carbonate is 96.9. The whiteness of fly ash was increased using a one stage thermal method ensuring the related cost of production would be not a major hurdle. The next aspect of the thesis involved incorporating as-received and heat treated fly ash samples in isotactic polypropylene up to 80 parts of fly ash per hundred resins (phr), demonstrating that fly ash content in polypropylene composites can be quite high with properly maintained combination of mechanical properties -- in particular up to 200 % improvement in Young's modulus and 63 % gain in notched impact properties, as explained in the thesis. Whilst the Young's modulus properties of the fly ash PP composites match very well with Kerner model, they lie in between the Rule of Mixture series and parallel. The tensile strength properties obtained in this research are at least 25 % higher than those predicted by Nielsen, Landon and Nicolais; whereas the strain to failure values are between 25 - 50 % higher than those predicted by Nielsen, and Smith. Whilst tensile strength of the fly ash filled polypropylene composites were less than the original polypropylene samples, as normally reported in the literature, in this thesis surface modification of fly ash particles by using 10% vinyl triethoxy silane (VTES) coupling agent gave a nominal increase in tensile strength especially at higher fly ash content. The final aspect involved study of oxidation behavior of fly ash filled polypropylene composites. Fillers, including fly ash can shorten the life time of polymers from both chemical as well as physical factors. As-received fly ash contains iron based impurities which may catalyze the anti oxidant in polypropylene, therefore reducing the service life time of the polymer. In this work, thermal treatment studies showed that the iron in fly ash can be changed to a chemically inert material so the effective service life of the polymer will only be influenced by physical factors. Therefore thermal treatment of fly ash not only increases the whiteness but also it reduces the risk of the filler on the life time of the polymer, and hence the composites.
2

Barevná modifikace Warteggova kresebného testu - typický způsob zpracování u dětí se SPU / The colour modification of Wartegg´s drawing test - typical method of processing test of LD (learning disorder) diagnosed children.

BOUDOVÁ, Adéla January 2013 (has links)
This graduation work is aboutthe typical characteristics of children diagnosed with learning disabilities in the color modification Wartegg drawing test. In the theoretical part, characterized the basis for research, which includes topics dealing with projective techniques and their use in children, which includes also Warteggův drawing test and its modifications. There are also topics have focused on specific learning disabilities, their social aspects, and artistic expression of children with this diagnosis and the graphic skills of children in general. Followed by part dealing with the colors, their use in psychodiagnostic and their symbolism. This section was prepared analyzing literature and its aim is characteristic Wartegg drawing test and color modifications.In the empirical part of the selected characters analyzed in terms of processing individual fields Wartegg drawing test, which are then processed statistically. The results of the research group are compared with the control group. The target of graduation work is determination of typical marks in processing colourmodification of Wartegg?s drawing test with learning disabilities diagnosed children compared to children of intact

Page generated in 0.0835 seconds