In-situ Cure and Cure Kinetic Analysis of a Liquid Rubber Modified Epoxy Resin

Abstract

The in-situ cure and cure kinetics of an epoxy resin based on diglycidyl ether of bisphenol A (DGEBA) polymerized with an anhydride hardener and its mixtures with a liquid polybutadiene rubber having hydroxyl functionality (HTPB) were studied using Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) in an isothermal mode. The cure reaction was monitored in-situ by FTIR spectroscopy by observing variation in intensity of epoxy, anhydride, and ester bands. The cure reaction mechanisms by which the network structure of epoxy was developed were discussed. Isothermal mode DSC measurements were performed at selected temperatures. The reaction followed an autocatalytic mechanism, and kinetic analysis was done by a phenomenological model developed by Kamal. Good fits were obtained between the autocatalytic model and the experimental data up to the vitrification state. Afterward, the reaction became diffusion controlled. The reaction during the later stages of cure was explained by introducing a diffusion factor, which agreed well with the kinetic data. The nature of the developing morphology of modified epoxies was analyzed by optical microscopy (OM) and small angle laser light scattering (SALLS) technique. The ultimate morphology of the cured blends was analyzed using scanning electron microscopy (SEM). The cure kinetics has been correlated with the developed morphology to get insight into the mechanism of reaction-induced microphase separation.

Advanced isoconversional cure kinetic analysis of epoxy/poly(furfuryl alcohol) bio‐resin system

“…Also, lowering the temperature, the rate, and the extent of reaction decreased. Thomas et al . also investigated the mixture of DGEBA epoxy resin and a liquid polybutadiene having hydroxyl functionality using Kamal model and found out its kinetic parameters.…”

Functionalized liquid natural rubber and liquid epoxidized natural rubber: A promising green toughening agent for polyester

“…The majority of published studies on toughened thermosets are based on various types of synthetic liquid rubbers, such as carboxyl‐terminated butadiene acrylonitrile (CTBN) copolymer, hydroxyl‐terminated polybutadiene (HTPB), vinyl‐terminated butadiene‐acrylonitrile, amine‐terminated butadiene acrylonitrile (ATBN), styrene‐butadiene, and acrylonitrile‐butadiene (NBR) . However, there are not many reports on liquid natural rubber (LNR).…”

Preparation and Characterization of Fluorinated Hydrophobic UV-Crosslinkable Thiol-Ene Polyurethane Coatings

“…In a typical example, HTPB (60 g, 30 mmol -OH) was dissolved with ethylacetate (20 mL) in a three-necked, round-bottom flask, and IPDI (6.67 g, 60 mmol -NCO) was added dropwise under magnetic stirring for 5 min, followed by the addition of three drops of DBTDL. The prepolymerization reaction was allowed to proceed for 2.5 h at 45 • C until the value of isocyanate reached the theoretical value by titration [34]. Afterward, BDO (0.68 g, 15 mmol -OH) dissolved in ethylacetate (40 mL) was added dropwise, and the reaction continued for another 3 h at 60 • C. Finally, HEA (1.74 g, 15 mmol -OH) was added into the flask, and the reaction mixture was stirred for about 3 h until the absorption peak of the -NCO group in the infrared spectra disappeared.…”