A thermodynamic model for thermoset polymer blends with reactive modifiers

Abstract

A new quantitative thermodynamic model for the prediction of phase equilibrium behaviour of thermoset‐reactive modifier polymer blends has been developed. The model combines the Flory–Huggins lattice theory with a group contribution theory for the prediction of the thermodynamics evolution. The model predicts the free energy of mixing as a function of blend composition, temperature, and degree of polymerisation. The evolution during polymerisation of both the entropy and enthalpy of mixing has been taken into account. Moreover, the reactions of both the thermoset and the modifier have been considered in the model. The model successfully interprets the trends observed in chemically induced phase separation (CIPS). Binodal and spinodal lines are calculated and the window available for phase separation is predicted. The model was evaluated using a diglycidyl ether bisphenol‐A epoxy cured with isophorone diamine, blended with epoxy functionalised dendritic hyperbranched polymers (HBP). This system underwent chemically induced phase separation during cure as revealed by cloud point measurements. Excellent agreement was obtained between the model and the experimental data when entropy and enthalpy variations associated with both the thermoset and the modifier cure were taken into account. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1893–1902, 2000

Homogeneously Dispersed Polyrotaxane in Epoxy Adhesive and Its Improvement in the Fracture Toughness

“…The significant difference in morphology between the PR-20 and PCL-20 adhesives is apparently unusual because the PR includes a large number of PCL chains that correspond to approximately 79–81 wt % . The well-known Flory–Huggins theory states that binary polymer blends linear polymers exhibit a stronger tendency for phase separation with an increase in their molecular weights , when each χ parameter has the same value. Because PR has a molecular weight that is 200 times larger than that of PCL, the homogeneous dispersion of the former suggested a larger negative χ parameter, as implied by the positive deviation on the T g curve.…”

Homogeneously Dispersed Polyrotaxane in Epoxy Adhesive and Its Improvement in the Fracture Toughness

“…The significant difference in morphology between the PR-20 and PCL-20 adhesives is apparently unusual because the PR includes a large number of PCL chains that correspond to approximately 79–81 wt % . The well-known Flory–Huggins theory states that binary polymer blends linear polymers exhibit a stronger tendency for phase separation with an increase in their molecular weights , when each χ parameter has the same value. Because PR has a molecular weight that is 200 times larger than that of PCL, the homogeneous dispersion of the former suggested a larger negative χ parameter, as implied by the positive deviation on the T g curve.…”

Interlaminar fracture toughness improvement in composites with hyperbranched polymer modified resin

“…From the work of Mezzenga et al [6,[23][24][25], it has been shown that a good compromise between toughness increase and the decrease in stiffness ranges from 5% to 20%. HBP contents studied herein were thus: 0%; 7.5%; 10%; 12.5% and 20%.…”

Modifications and applications of hyperbranched aliphatic polyesters based on dimethylolpropionic acid

“…An advantage of these tougheners is that they can meet the need of property improvement without loss of the basic performance of the resin system. A new thermodynamic theory model for the prediction of the phase equilibrium behavior of thermoset/reactive modifier polymer blends has also been suggested, 113,114 and a new procedure for the calculation of solubility parameter evolution during polymerization has been developed for amine-cured epoxy systems, which allows quantitative thermodynamic modeling of chemically induced phase separation. 115 The addition of HBPEs into epoxy resin has been shown to affect thermodynamic behavior, gelling and network build-up, 116,117 as well as final morphology.…”

Homogeneously Dispersed Polyrotaxane in Epoxy Adhesive and Its Improvement in the Fracture Toughness

“…The significant difference in morphology between the PR-20 and PCL-20 adhesives is apparently unusual because the PR includes a large number of PCL chains that correspond to approximately 79–81 wt % . The well-known Flory–Huggins theory states that binary polymer blends linear polymers exhibit a stronger tendency for phase separation with an increase in their molecular weights , when each χ parameter has the same value. Because PR has a molecular weight that is 200 times larger than that of PCL, the homogeneous dispersion of the former suggested a larger negative χ parameter, as implied by the positive deviation on the T g curve.…”

Interlaminar fracture toughness improvement in composites with hyperbranched polymer modified resin

“…From the work of Mezzenga et al [6,[23][24][25], it has been shown that a good compromise between toughness increase and the decrease in stiffness ranges from 5% to 20%. HBP contents studied herein were thus: 0%; 7.5%; 10%; 12.5% and 20%.…”

Modifications and applications of hyperbranched aliphatic polyesters based on dimethylolpropionic acid

“…An advantage of these tougheners is that they can meet the need of property improvement without loss of the basic performance of the resin system. A new thermodynamic theory model for the prediction of the phase equilibrium behavior of thermoset/reactive modifier polymer blends has also been suggested, 113,114 and a new procedure for the calculation of solubility parameter evolution during polymerization has been developed for amine-cured epoxy systems, which allows quantitative thermodynamic modeling of chemically induced phase separation. 115 The addition of HBPEs into epoxy resin has been shown to affect thermodynamic behavior, gelling and network build-up, 116,117 as well as final morphology.…”

Homogeneously Dispersed Polyrotaxane in Epoxy Adhesive and Its Improvement in the Fracture Toughness

“…The significant difference in morphology between the PR-20 and PCL-20 adhesives is apparently unusual because the PR includes a large number of PCL chains that correspond to approximately 79–81 wt % . The well-known Flory–Huggins theory states that binary polymer blends linear polymers exhibit a stronger tendency for phase separation with an increase in their molecular weights , when each χ parameter has the same value. Because PR has a molecular weight that is 200 times larger than that of PCL, the homogeneous dispersion of the former suggested a larger negative χ parameter, as implied by the positive deviation on the T g curve.…”

Interlaminar fracture toughness improvement in composites with hyperbranched polymer modified resin

“…From the work of Mezzenga et al [6,[23][24][25], it has been shown that a good compromise between toughness increase and the decrease in stiffness ranges from 5% to 20%. HBP contents studied herein were thus: 0%; 7.5%; 10%; 12.5% and 20%.…”

Modifications and applications of hyperbranched aliphatic polyesters based on dimethylolpropionic acid

“…An advantage of these tougheners is that they can meet the need of property improvement without loss of the basic performance of the resin system. A new thermodynamic theory model for the prediction of the phase equilibrium behavior of thermoset/reactive modifier polymer blends has also been suggested, 113,114 and a new procedure for the calculation of solubility parameter evolution during polymerization has been developed for amine-cured epoxy systems, which allows quantitative thermodynamic modeling of chemically induced phase separation. 115 The addition of HBPEs into epoxy resin has been shown to affect thermodynamic behavior, gelling and network build-up, 116,117 as well as final morphology.…”