Developing toughened aromatic polybenzoxazines using thermoplastic oligomers and telechelics, part 1: Preparation and characterization of the functionalized oligomers

Abstract

The preparation and characterization of three families of thermoplastic oligomers (M n 5 2918-13263 g mol 21 ) based on polyarylsulfone (PSU) differing in both molecular weight and terminal functionality and one series of polyarylethersulfone (PES) of different molecular weights is reported. Infrared and nuclear magnetic resonance spectroscopy data support the formation of both the hydroxyl terminated oligomers and conversion (67-89% depending on molecular weight) to the telechelic PSU oligomer bearing reactive benzoxazine groups. Differential scanning calorimetry reveals that the onset of homopolymerization in the telechelic PSU oligomer occurs at around 100 C (peak maximum 125 C at 10 K/min) and rescans show values of the glass transition (for the homopolymers) ranging from 124 to 167 C depending on molecular weight. The influence on the oligomer backbone and terminal functionality is examined using thermal analysis.

Toughening Mechanisms in Aromatic Polybenzoxazines Using Thermoplastic Oligomers and Telechelics

“…In the interests of brevity the characterization data have been deposited as Supporting Information. The oligomers based on polyarylsulfone (PES) or polyarylethersulfone (PSU) (Figure ) were prepared during a study of oligomeric engineering thermoplastics. , …”

“…The synthetic procedures (e.g., on a 20 g scale) used were all based on published methods, − albeit modified versions in order to achieve lower molecular weight species. The preparation and characterization of the oligomers has previously been submitted for publication and the salient features are deposited as Supporting Information in that work.…”

Fracture behavior of high‐performance carbon fiber composites toughened by reactive polyetherimide

“…The effectiveness of toughening from particle bridging relies on the size of thermoplastic particles, number of particles, and most importantly, adhesion between the particles and resin matrix. Interfacial adhesion between the thermoplastic particles and resin matrix can be optimized and enhanced by introducing strong chemical bonding or creating molecular entanglements between the two phases 47–49 …”

“…Interfacial adhesion between the thermoplastic particles and resin matrix can be optimized and enhanced by introducing strong chemical bonding or creating molecular entanglements between the two phases. [47][48][49] In general, polymer chain ends may act as defects and create weak points to cause premature failure upon mechanical loading. 50 Toughening agents having reactive chain ends or pendant functional groups can react with thermoset precursors via covalent bonding and become part of a cross-linked network to help toughen the epoxy matrix.…”