Cure Path Dependence of Reaction-Induced Phase Separation In Glassy Amorphous Polymer Networks
Document Type
Conference Proceeding
Publication Date
1-1-2020
School
Polymer Science and Engineering
Abstract
Reaction induced phase separation of high Tg thermoplastics from epoxide/amine networks during cure is one common method for the toughening of networks. However, the toughness realized in the final network entirely depends on the morphology, which can range from droplet dispersed, co-continuous, to phase inverted. An additional complication the dependence of mechanism of phase separation on the cure path on the. Spinodal decomposition is the preferred phase separation mechanism, but the competing process is nucleation growth phase separation. To realize maximum toughening effect, co-continuous morphology is desired, and the most consistent morphologies are developed through the spinodal decomposition phase separation mechanism. For this work, tetraglycidyl -4, 4'-diaminodiphenylmethane (TGDDM), 4, 4'-diaminodiphenylsulphone (44DDS), and non-reactive polyetherimide (PEI) are dissolved in solvent until homogenous, then the solvent is removed and the 44DDS is clarified at 125 °C until only the b-staged, transparent yellow film remains. Rheology from clarified sample through gelation resolves the phase separation mechanism. Samples are cured from 80 °C to 180 °C at ramp rates of 1 and 5 °C/min and remain at the 180 °C isotherm for two hours. Samples are further post cured at 220 °C for an additional hour to ensure full cure. Morphology of cured networks is examined with atomic force microscopy-based infrared spectroscopy (AFM-IR), which additionally establishes the chemical identity of each phase. Morphology is confirmed with optical microscopy, and dynamic mechanical analysis (DMA), where thermomechanical response correlates with morphology type. Final morphology depends heavily on the thermoplastic loading level, while the mechanism of phase separation can depend upon the cure rate. At all cure rates, co-continuous networks are realized when PEI loading ≥ 15 wt.%.
Publication Title
Composites and Advanced Materials Expo, CAMX 2020
Recommended Citation
Hartline, M.,
Bates, J.,
Prine, N.,
Walker, D.,
Garcia, D.,
Gu, X.,
Wiggins, J.
(2020). Cure Path Dependence of Reaction-Induced Phase Separation In Glassy Amorphous Polymer Networks. Composites and Advanced Materials Expo, CAMX 2020.
Available at: https://aquila.usm.edu/fac_pubs/19445
COinS