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  • 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

Aggregation and Redispersion of Switchable Latexes

O'NEILL, CATHERINE 26 September 2011 (has links)
Amidine-based switchable surfactants can be used as stabilizers during emulsion polymerization and the resulting latexes can then be destabilized by the removal of CO2. High Tg polymers have been successfully redispersed, as shown by recovery of primary particle size (measured by light scattering methods), but an input of energy was required. Sonication was the first method used, but lower-energy methods such as rotor-stators and a blender have also been successful in redispersing aggregated latexes. Colloidal stability was found to be reversible for at least three aggregation/redispersion cycles, and redispersibility was retained after the removal of water and addition of fresh water. Stimuli-responsive polymer colloids with reversible colloidal stability may have many uses. The shipping of latexes, for example, would be easier and less energy intensive if the latex particles could be aggregated and the bulk of the water removed. The latexes would then have to be redispersed prior to use. Switchable surfactants have also been used for the semi-continuous copolymerization of butyl acrylate and methyl methacrylate to form a high solids content (42 wt%), low-Tg latex. The latex can be destabilized with air and heat but cannot undergo redispersion because the low Tg polymer particles fuse upon aggregation. The copolymer, when dried at room temperature, formed a continuous film. Latexes with high solids content and low Tg’s are representative of latex paint formulations. Because the switchable surfactants have been shown to be successful in preparing these latexes, it is possible that they may be useful in the latex paint industry, for example as fast setting paints. / Thesis (Master, Chemistry) -- Queen's University, 2011-09-26 13:18:33.905
2

Studium flexibility a adheze cementových lepidel při různém stupni modifikace polymerním pojivem / Study of deformation and adhesion of cement adhesives at different stages of polymeric modification

Kozielová, Silvie January 2019 (has links)
The content of the diploma thesis deals with the study of the flexibility and adhesion of cement tile adhesives, which are modified by a polymeric additive. The effects of the quantity and type of redispersible polymer powder used on the properties of the adhesives, in particular on the deformability of adhesives and their adhesion, are monitored. The theoretical part summarizes the basic data concerning classification of the ceramic tiles, information about the adhesives, the processed part concerning the polymer modified adhesives and the effects of the polymeric additives on their properties. The practical part deals primarily with the study of adhesion and flexibility of polymer modified adhesives and study of microstructure of selected materials.
3

Studium vlhkostně-transportních vlastností polymer-cementových stěrek pro vnější kontaktní zateplovací systémy budov / Study of the moisture-transport properties of polymer cementious screed for external thermal insulation composite systems

Janíček, Vít January 2019 (has links)
This diploma thesis deals with study of the moisture-transport properties of polymer cementious ETICS mortars at different doses of redispersible polymer powder. The effect of aerate on these screeds is also investigated. The thesis also evaluates the effect of use various external surface treatments due to risk of cumulate moisture in the perimeter structure.
4

Elastomerní plniva jako potencální surovina pro betony a malty / Elastomer fillers as a potential raw material for concrete and mortar products

Jankech, Filip January 2017 (has links)
To attain a sustainable development in the field of building materials, it is necessary to consider environmental, economic, and social aspects of the industrial production. This thesis addresses the first two aspects. Both theoretical and practical research were implemented in order to study the possibility to replace the commonly used RDPs, that are being used in the dry-mix mortar industry as a primary additive, with the industrially processed elastomer waste materials, such as recycled tire rubber. The review of the scientific literature processed within the theoretical research discloses the state of the art in the field of polymer modification of the mortar products and the effect of the commonly used modifiers and elastomer fillers on the performance of mortar and concrete products. The experimental research was implemented to study the possibility of the replacement of the RDPs for the elastomer fillers. The performance of fresh and hardened mortar containing various amounts of elastomer particles was studied. The results indicate, that the partial replacement could be feasible without worsening the performance of the product.

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