Pioneering high-shear continuous polymerization reactor engineering developed in the School of Polymer Science and Engineering at the University of Southern Mississippi demonstrates a library of benzoxazine monomers and prepolymer alloys from high-purity monofunctional and multifunctional precursors using a one-step synthetic method. Our approach validates the simultaneous synthesis of multiple benzoxazine monomers to yield disrupted crystallinity and create complex formulations with improved processability. Methyl substituted aniline and phenol derivative benzoxazine monomers of varying functionalities are co-synthesized via the solvent-free CHSR process with desirable prepolymer rheology and cured network thermomechanical properties for composite matrix polymers in &lt;60 seconds reactor time from monomer to finished prepolymer.  To illustrate the utility of the CHSR processes, multifunctional benzoxazine monomers are simultaneously co-synthesized to create viscosity modified complex prepolymers. The chemical structures and purity are confirmed via proton nuclear magnetic resonance spectroscopy. Differential scanning calorimetry and non-isothermal rheology elucidate thermal transitions, as well as the copolymerization and gelation behavior of both monomer alloys and complex prepolymers. Dynamic mechanical analysis is employed to quantify Tg and storage modulus of the resulting polybenzoxazine networks. Thermogravimetric analysis quantifies the thermal stability and inert char yield of the various networks. Further demonstration will review how the CHSR is employed for the rapid advancement of specific desirable new high-char based benzoxazines — illustrating how alloys and simultaneously synthesized complex prepolymers can be leveraged to optimize rheological behavior for processability, while retaining Tg over 350C, and inert char yield in excess of 60% at 900C.  Our presentation culminates with the future direction of our research for 100% benzoxazine prepolymers to create room-temperature tacky films for unidirectional carbon fiber prepreg tapes.

Benzoxazine polymer continuous reactors

ACS Spring 2022

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