Abstract
ABSTRACTThe 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. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47383.
Highlights
Epoxy resins are widely used in structural composites for many reasons such as their excellent strength to weight ratio, comparative ease of processability, low shrinkage during cure and corrosion and chemical resistance, to name a few
3.1 Reaction Kinetics Rheology The changes in complex viscosity during cure for each resin system is shown in Figure 2a) which reveals an initial decrease in viscosity as the mobility of the monomers increases during heating, followed by an exponential increase as the growing polymer chains connect and approach gelation
A series of tri aromatic ether linked amines differing only by their aromatic substitution patterns were investigated with respect to their reaction kinetics and structure property relationships when cured with bisphenol F (BisF) epoxy
Summary
Epoxy resins are widely used in structural composites for many reasons such as their excellent strength to weight ratio, comparative ease of processability, low shrinkage during cure and corrosion and chemical resistance, to name a few. Despite these advantages, mass market applications have remained limited because manufacturing high quality components at low cost has proved challenging. Relevant to liquid moulding fabrication technologies, is to design a resin that is inherently deformation resistant without the need for further modification This can be achieved by incorporating structural features that enhance flexibility or mobility within the backbone of the polymer while potentially minimising deleterious impact upon other properties. All of the results were contrasted against a common high performance network such as BisF cured with [4,4] diamino diphenyl sulphone (44DDS)
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