The work presented in this Thesis describes the use of reactive all aromatic liquid crystalline thermosetting resins for fiber reinforced composite applications. One of the challenges associated with reactive LC thermoplastic resins is that the melting temperature ( T k lc ) is typically close to or above the decomposition temperature. In order to improve the melt processing characteristics of reactive liquid crystal resins, but without compromising the after cure (thermo)mechanical properties, two synthetic approaches have been explored: 1-control of the polymer molecular weight by using phenylethynyl reactive end groups and 2- by introducing non linear co monomers.

The reaction kinetics and structure property relationships of isomeric tri-aromatic ether-linked amines based on the structure bis (aminophenoxy) benzene, cured with diglycidyl ether of bisphenol F (BisF) are investigated in this study. Reaction kinetics are explored using rheological and calorimetric measurements, whereas structure property relationships are determined from their flexural properties, dynamic mechanical properties (DMTA), and thermogravimetric analysis (TGA). A BisF network cured with 4,4 diamino diphenyl sulphone (44 DDS) is used as a benchmark to represent a commercially available high-performance resin system. Varying the substitution of the ether linkages on the aromatic groups from ortho, meta to para was found to have a significant impact on reactivity and network properties after cure. The variations are explained in terms of inductive and resonance effects primarily acting on the outer aromatic rings. Interestingly, however, these same effects acting on the central aromatic ring also impact upon reactivity despite their proximity from the amines. Mechanical and thermal properties are explained by changes in the short-range molecular mobility within the network architecture such as phenylene rotations or π flips and are experimentally validated from the breadth and position of the subambient γ relaxations.

The reaction kinetics and structure property relationships of isomeric tri-aromatic ether linked amines based on the structure bis (aminophenoxy) benzene cured with diglycidyl ether of bisphenol F (BisF) are investigated in this study. Reaction kinetics are explored using rheological and calorimetric measurements, while structure property relationships are determined from flexural properties, dynamic mechanical properties (DMTA) and thermogravimetric analysis (TGA). The isomers had a varied substitution pattern from ortho, meta to para, and had a significant impact on both amine reactivity and properties after cure. All of the observed changes could be explained in terms of inductive and resonance effects dominated by the outer aromatic rings. The mechanical and thermal properties were understood in terms of the variations in short molecular mobility within the network architecture, more specifically the extent to which phenylene rotations or π flips occur and is experimentally validated from the breadth of the sub-ambient γ relaxations.