Interdiffusion of thermoplastics and epoxy resin precursors: investigations using experimental and molecular dynamics methods

Abstract

Toughening of epoxy thermosets with thermoplastics is an important avenue towards improved properties of high‐performance systems. The main focus of the work reported was to study the complex issue of interdiffusion between thermoplastics and epoxy resin precursors, using a combination of experimental and numerical simulation methods, in order to understand the key parameters driving the process. Diameter changes of thermoplastic filaments in contact with epoxide and diamine precursors have been followed and an original approach using carbon nanotubes as tracers of the filament swelling front has been developed. This method shows that the improved mobility of low‐molecular‐weight resin monomers as well as the greater mobility of phenoxy of lower glass transition temperature as compared to poly(ether sulfone) control dissolution by favouring the penetration of precursors into the thermoplastic and lead to both swelling of the outer part of the filaments and reduction of the inner unaffected core. Simulation by molecular dynamics supports the idea that diffusion of polymer macromolecules remains limited compared to the dominant effect of precursor diffusion. Indeed, low diffusion coefficients have been predicted for thermoplastic oligomers compared to resin monomers. For the latter, the calculated values correlate well with the experimental data measured during interdiffusion. Copyright © 2012 Society of Chemical Industry

Co-Bonded Hybrid Thermoplastic-Thermoset Composite Interphase: Process-Microstructure-Property Correlation

“…Moreover, the changes in the temperature were associated with the alterations in interdiffusion kinetics by increasing the molecular mobilities indicated by a reduction in the viscosity of the resin as seen in Figure 9 c [ 28 , 51 ]. In Figure 9 c, it was found that the viscosity of UPR changed linearly with temperature in logarithmic scale and a small increase in temperature reduces the viscosity considerably which can promote the interdiffusion and result in thicker interphase.…”

Fabrication and characterization of hydrophilic poly(ε‐caprolactone)/pluronic P123 electrospun fibers

“… and where and denotes the position vector of the atom at time and , respectively. The angular brackets denote averaging of all choices of time origin within a dynamics trajectory . From MSD vs time curve it can be speculated that the diffusion of water molecules is also greatly influenced by the surface hydrophilization (Figure ).…”

Phenoxy nanocomposite carriers for delivery of nanofillers in epoxy matrix for resin transfer molding (RTM)-manufactured composites

“…In both cases, the residual glassy layer of the filament completely disappears before 20 min, i.e. much before gelation of the RTM6, as a result of interdiffusion between the low molar mass resin precursors and the polymer chains [36]. In contrast to organoclay, the black MWCNT prevent optical detection of the interface between the inner core of the filament and its gel layer containing swollen nanocomposite (Fig.…”

“…After complete mold filling and as a result of the temperature program applied to the system, the (amorphous) TP progressively dissolves into the epoxy resin precursor prior to substantial curing and gelling. Finally, the RIPS mechanism generates a morphology gradient that is a function of the local blend composition resulting from the interdiffusion between the TP and the resin precursors [36]. This approach can lead to a significant improvement of the composite performance in terms of mode I crack propagation resistance which is the dominant failure mode in compression after impact (CAI) [24,27,28,34,37].…”