Curing behaviour of epoxy resins with a diamine bearing an azobenzene group

Abstract

N,N-Diglycidylaniline (DGA) has been cured with the new chromophore 2,4-diamino-4'-methylazobenzene (DMAB). The curing kinetics of this aminophenyl epoxy resin/DMAB system was studied in isothermal experiments by means of differential scanning calorimetry. Autocatalytic behaviour is seen in the first stage of the cure and can be described by a model proposed by Kamal. The later stage is practically diffusion-controlled (beyond the glass transition). The diffusion effect is introduced into Kamal's equation. Parameters such as rate constants and activation energies are calculated. Good agreement between calculations and experimental data is found. The curing kinetics of bifunctional DGA is compared with that of trifunctional N,N-diglycidyl-4-glycidyloxyaniline (DGOA) with the same tetrafunctional curing agent DMAB. The rate constants for DGA + DMBA are slightly higher than those for the DGOA + DMAB system. The activation energy for the former (E 1 = 64.1 kJ/mol, E 2 = 56.2 kJ/mol) is lower than for the latter system (E 1 = 71.6 kJ/mol, E 2 = 70.5 kJ/mol). DGA needs to be cured at a lower temperature than DGOA. The relationships between glass transition temperature, T g , and rate of conversion and time of curing is discussed as well. DGA cured with DMAB exhibits a lower T g (220°C) and thermal stability than DGOA + DMAB (T g = 240°C) because of the lower functionality of the DGA resin. Preliminary investigations of optical grating recording in the new material were carried out. The presence of azobenzene groups in such epoxy systems enables their application as potential materials for holography.

Very efficient surface relief holographic materials based on azobenzene-containing epoxy resins cured in films

“…In the studied material surface relief modulation of 600 nm at grating period of 2 mm could be achieved by inscription time of ca. 12,13 We will show below that the composition might have a drastic influence on the performance. An AFM image of the relief grating and the corresponding cross-section of the grating are shown in Fig.…”

“…With other words the longer irradiation the deeper the generated surface relief. 12 In other reports 13 different fabrication technology was used for the preparation. 5 min.…”

Optical Studies of Poly(hydroxy imide) to Polybenzoxazole Thermal Rearrangement

“…[ 1 ] Moreover, low dielectric constant, optical transparency, easy processability, and adjustment with semiconductor device technology requirements cause polyimides and their derivatives good candidates for optoelectronic and photovoltaic applications. [2][3][4][5][6][7] Among various applications, the use of PI as membranes for gas separation technology has become of great interest due to their signifi cantly better permselective performance comparing to typical glassy polymers. [ 8 ] PI with hydroxyl (OH) side groups in ortho-position have gained particular attention recently since they allow membrane materials with extremely high gas permeability and reasonable permselectivity to be obtained as a comonomers in HPI-PI on the position of transmittance edge was discussed in that work.…”

A kind of novel silicon-, phosphorus-containing hybrid material and its use as the modifier of DGEBA epoxy resins

“…In order to improve heat resistance, the cross-linking density of epoxy resins has been attempted to increase, or rigid groups have been introduced to copolymerize with epoxy resin [9][10][11][12]. However, these methods have been confirmed that they will induce friability.…”