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Title of Thesis

Institute/University/Department Details
Department of Chemistry/ Quaid-i-Azam University, Islamabad
Inorganic Chemistry
Number of Pages
Keywords (Extracted from title, table of contents and abstract of thesis)
organoceramic nanocomposites, polyamides, clay, polyamide-clay nanocomposites, organically modified layered silicate, polymer-layered silicate, oligomer

Various types of polyamide-clay nanocomposites were synthesized using the solution intercalation method. Compatibility between the two phases was achieved by suitably modifying both the phases for better improvement in the physical and mechanical properties of the nanocomposites. Different strategies have been adopted in order to develop various types of interactions among the two disparate phases. Therefore, the hydrophilic nature of montmorillonite was changed into organophilic by ion-exchange method using various intercalating agents with different chain lengths and functionality, such as long chain alkyl amine, amino benzoic acid, diamines and amine terminated oligomer. The intercalation was carried out in aqueous medium except for the oligomeric species because of their solubility in organic solvents like DMSO. The increase in d-spacing upon intercalation was monitored through XRD. So, these modifications in the clay structure were carried out in order to have good compatibility, uniform and homogenous dispersion in the polyamide matrices. Three different types of linear polyamide chains of either aromatic and aliphatic or purely aromatic nature were synthesized by condensing different diamines with diacid chlorides under anhydrous conditions.

The structure of these polyamide matrices was elucidated through FT-IR, IH and l3C NMR spectroscopy. The molecular weight and molecular weight distributions of these polyamide matrices were determined using GPC and LLS techniques. Furthermore, these polyamide chains were selectively end-capped with either amine or carbonyl chloride end groups in order to create better interaction with the modified clays. Thin transparent films of these nanocomposites obtained were characterized with regards to XRD, TEM, mechanical, TGA, DSC and water absorption measurements. XRD and TEM results revealed the formation of exfoliated and intercalated nanocomposites. The tensile strength of nanocomposites improved considerably relative to the pure polyamides. Various polyamide based nanocomposites were found to be thermally stable. Increase in the glass transition temperature (Tg) values relative to pure polyamides determined by DSC gave a measure of interfacial interactions between polyamides and organoclays. The percent water absorption of these nanocomposite films was found to be much reduced upon the addition of modified layered silicates.

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3695.71 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents
239.89 KB
2 1 Introduction 1
896.53 KB
  1.1 Polymers 2
  1.2 Structure and properties of layered silicates 4
  1.3 Structure and properties of organically modified layered silicate (OMLS) 6
  1.4 Composites 8
  1.5 Classification of composites based on source 9
  1.6 Classification of composites based on matrix used 11
  1.7 Types of polymer clay composites 13
  1.8 Polymer-layered silicate (PLS) nanocomposite technology 16
  1.9 Preparative techniques 17
  1.10 Techniques used for the characterization of nanocomposites 19
  1.11 Overview of polymer layered silicate nanocomposites 21
  1.12 Present Work 52
  1.13 Status and prospects of polymer layered silicate nanocomposites 54
3 2 Experimental 61
527 KB
  2.1 Chemicals 61
  2.2 Synthesis of polyamide matrices 63
  2.3 Synthesis of amine terminated oligomer 70
  2.4 Intercalation of montmorillonite 71
  2.5 Preparation of nanocomposites 73
  2.6 Characterization 99
4 3 Results and Discussion 110
2130.68 KB
  3.1 Characterization of polyamide matrices 111
  3.2 Characterization of modified montmorillonite through XRD 134
  3.3 Characterization of nanocomposites 135
  3.4 Overview of different properties of nanocomposites 213
  3.5 Conclusions 216
  3.6 Future plan 217
5 4 References 219
190.92 KB
  4.1 List of Publications 234