Tailoring the viscoelasticity of epoxy thermosets

Abstract

This research work is aimed to understand the effect of epoxy resin chemistry on the viscoelasticity of the cured epoxy thermosets. In this article, two model systems are selected based on epoxy‐amine reactants. In the model Systems I, the functionality of the epoxy is varied. In model System II, the pendant (side) chain length in the amine is varied. It is found that by varying the initial properties (e.g., functionality, pendant chain length, mixing ratio (r), aromaticity, etc.) the network properties (crosslink density and flexibility) of the cured (or hardened) epoxy changed. The changes (or shift) in the viscoelastic properties (or viscoelasticity) of the cured epoxy is mainly due the changes in the network properties. Further, to study the time and temperature effects the viscoelastic master curves for the two model systems are generated using Time‐Temperature‐Superposition (TTS) principle. The shift in the viscoelastic master curves is modeled with a simple Kohlrausch‐Williams‐Watts (KWW) fit function. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Smoke suppression properties of epoxy crosslinked structure and intumescent fire retardant in epoxy‐based intumescent fire‐retardant coating

“…Figure shows the specific optical density ( D s ) curves of 2‐mm‐thick samples at a flux of 25 kW m − under flame or flameless combustion condition. It can be seen from Figure that the D s curves of both EP/PA and IFR‐EP have lower values without flame, indicating that the combustible materials derived from the degradation will be ignited to generate more smoke.…”

“… Specific optical density curves of EP/PA (a) and IFR‐EP (b) at a flux of 25 kW m − with flame. [Color figure can be viewed in the online issue, which is available at http://wileyonlinelibrary.com.…”

“…The static smoke production behaviors of resins were characterized using a smoke density instrument (JQSYM‐2) according to GB8323.2‐2008 and ISO5659.2‐2006 with an incident flux of 25 kW m − . Each sample was put into an aluminum mold; the dimensions of test samples were 75 mm × 75 mm × 2 mm, 75 mm × 75 mm × 4 mm or 75 mm × 75 mm × 6 mm.…”

“…The cone calorimeter (Stanton Redcroft, UK) tests were performed according to ISO 5660 standard procedures with an incident flux of 35 kW m − or 50 kW m − . Each sample was wrapped in aluminum foil, which was then put into the sample holder in the horizontal orientation for testing.…”

“…With the development of polymeric materials, more and more natural and synthetic polymers have been used in a wide variety of industrial and household products . Epoxy resin (EP) is among the most important materials in modern polymer industries because of its balance of excellent heat, solvent, moisture and chemical resistance, good mechanical and electrical properties, and satisfactory adherence to many substrates . Polyamide resin (PA), which is an excellent curing agent for EP, can provide highly crosslinked network, tough and flexible film, and hydrophobicity to the coating.…”