Effect of ortho-diallyl bisphenol A on the processability of phthalonitrile-based resin and their fiber-reinforced laminates

Designing and Preparation of Fiber-Reinforced Composites with Enhanced Interface Adhesion

The interfacial properties between fibers and resin matrices show great influence on the properties of fiber-reinforced composites. In this work, phthalonitrile containing benzoxazine (BA-ph) was chosen as the resin matrix, which combined with the glass fiber (GF) to prepare reinforced composite laminates at low temperature (200 °C). The poly(arylene ether nitrile) (PEN) was used to modify the GF and BA-ph matrix. Curing behaviors of the BA-ph/PEN were investigated with Differential scanning calorimetric (DSC) and Dynamic rheological analysis (DRA), and results indicated that the polymerization would be hindered by PEN due to the dilution effects. Moreover, the formation of triazine rings which assigning to the ring-forming polymerization of nitrile groups in BA-ph and PEN could improve the compatibility of BA-ph and PEN in the matrix. The SEM images of the fracture surface of the composites revealed that the brittleness of BA-ph matrix and interfacial adhesion between GFs and matrix was improved. The enhanced interfacial adhesion was detailedly discussed from the perspective of physical entanglement and the copolymerization between PEN chains on the surface of GFs and BA-ph/PEN matrix. The results of DMA also explained the toughness of BA-ph/PEN matrix, the semi-interpenetrating polymer networks and the interfacial adhesion. In sum, a feasible strategy that modifies the surface of GFs and the brittleness of the thermosetting matrix by high-performance thermoplastic polymers, which can be employed to prepare the composite laminates with improved properties.

Dynamic and Static Mechanical Properties of Crosslinked Polymer Matrices: Multiscale Simulations and Experiments

We studied the static and dynamic mechanical properties of crosslinked polymer matrices using multiscale simulations and experiments. We continued to develop the multiscale methodology for generating atomistic polymer networks, and applied it to the case of phthalonitrile resin. The mechanical properties of the resulting networks were analyzed using atomistic molecular dynamics (MD) and dissipative particle dynamics (DPD). The Young’s and storage moduli increased with conversion, due both to the appearance of a network of covalent bonds, and to freezing of degrees of freedom and lowering of the glass transition temperature during crosslinking. The simulations’ data showed good quantitative agreement with experimental dynamic mechanical analysis measurements at temperatures below the glass transition. The data obtained in MD and DPD simulations at elevated temperatures were conformable. This makes it possible to use the suggested approach for the prediction of mechanical properties of a broad range of polymer matrices, including ones with high structural heterogeneity.