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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

Crystallinity in linear polyamides : a study using melt blending with small-molecule diluents

Pockett, John January 2004 (has links)
Linear polyamides, commonly known as Nylons, are widely used for their high melting temperatures, heat stability, toughness and abrasion resistance, allowing diverse commercial applications such as carpets, nylon stockings and automotive parts. The work here has possible ramifications for membrane production and drug delivery systems and makes a scientific contribution to the area of binary polymer/diluent systems where the polymer is semicrystalline and the diluent crystallises at a quite different temperature to the polymer. Melt blended crystalline/crystalline systems have, so far, not received the attention that amorphous/amorphous or crystalline/amorphous systems have, perhaps due to the complexity of the morphology that often results within such systems.
2

Hyperbranched Aromatic Polyesters and Their Application in Blends of Linear Polyamides

Fan, Zhirong 22 September 2009 (has links) (PDF)
In the last two decades, hyperbranched (hb) polymers have drawn much attention and obtained intensive research activities both from industry and academia. They are known to have unique and interesting properties which derive from their three dimensional structure and the large number of functional groups. These structural characteristics provide high possibilities for controlling functional group interactions and modifications of other polymers in blends and therefore, they are expected to result in novel materials with desired properties. Furthermore, the easy synthetic accessibility of hb polymers by one-pot synthesis is advantageous as well and allows easy scale-up of laboratory reactions. Having the characteristics as mentioned above, hb polymers are considered good candidates for blend components or melt processing modifiers. In fact, hb polymers have already been used as blend components or additives aiming for different effects. In many cases, reduced viscosity and formation of miscible blends were observed by modification of a linear matrix polymer with hb polymers. More information will be introduced in the following theoretical section. In this work two hb polyester systems based on AB2 and A2+B3 approaches were synthesized and studied. Their possible applications as additives in the blends of linear polyamides were investigated.
3

Hyperbranched Aromatic Polyesters and Their Application in Blends of Linear Polyamides

Fan, Zhirong 26 August 2009 (has links)
In the last two decades, hyperbranched (hb) polymers have drawn much attention and obtained intensive research activities both from industry and academia. They are known to have unique and interesting properties which derive from their three dimensional structure and the large number of functional groups. These structural characteristics provide high possibilities for controlling functional group interactions and modifications of other polymers in blends and therefore, they are expected to result in novel materials with desired properties. Furthermore, the easy synthetic accessibility of hb polymers by one-pot synthesis is advantageous as well and allows easy scale-up of laboratory reactions. Having the characteristics as mentioned above, hb polymers are considered good candidates for blend components or melt processing modifiers. In fact, hb polymers have already been used as blend components or additives aiming for different effects. In many cases, reduced viscosity and formation of miscible blends were observed by modification of a linear matrix polymer with hb polymers. More information will be introduced in the following theoretical section. In this work two hb polyester systems based on AB2 and A2+B3 approaches were synthesized and studied. Their possible applications as additives in the blends of linear polyamides were investigated.

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