Toughening Mechanisms in Aromatic Polybenzoxazines Using Thermoplastic Oligomers and Telechelics

Abstract

B i s ( 3 , 4 -d i h y d r o -3 -p h e n y l -2 H -1 , 3benzoxazine)propane (BA-a) is blended with oligomers of polyarylsulfone (PSU) and polyarylethersulfone (PES) of different low/intermediate molecular weights (3000−12 000 g mol −1 ) and terminal functionality (chloro-, hydroxyl-or benzoxazinyl-(Bz)). Fracture toughness (K IC ) is observed to increase from 0.8 MPa m 0.5 for cured BA-a to 1 MPa m 0.5 with the incorporation of 10 wt % PSU-Bz (12 000 g mol −1 ). Generally, greater improvements in K IC are observed for the PES oligomers compared with the PSU oligomers of equivalent molecular weight. The terminal functionality of the thermoplastic has a lesser effect on improving toughness than increasing the molecular weight or the nature of the polymer backbone. Surface analysis of the fractured surfaces show greater phase separation and crack pinning in the PES toughened system. Where crack pinning is less obvious, as in the case of hydroxyl-terminated PES (of 6000 g mol −1 ), this coincides with a drop in fracture toughness.

Significant Improvement on Polybenzoxazine Toughness Achieved by Amine/Benzoxazine Copolymerization‐Induced Phase Separation

“…Blending with other materials such as liquid rubber and thermoplastic has been reported to effectively improve the toughness of various polybenzoxazine‐based materials. These modifiers usually induce phase separated structures, which are able to change crack direction and absorb impact energy, leading to improved toughening properties when compared to the pure polybenzoxazine resin synthesized via a bulk polymerization.…”

A curing system of benzoxazine with amine: reactivity, reaction mechanism and material properties

“…7 Benzoxazines are typically synthesized from phenol, amine, and formaldehyde via a Mannich reaction. [19][20][21][22][23][24][25][26][27][28][29][30][31][32] To cure 1,3-benzoxazines, thermally accelerated polymerization has been the main focus for most researchers for a long time. There have been a lot of successful reports on the development of benzoxazine monomers to improve material performance or expand the range of their applications, 8 for example, lowering the polymerization temperature by introducing hydroxyl, 9,10 acetylene, 11,12 N-allyl, 13 and carboxylic acid groups 14 to benzoxazine compounds, increasing the cross-linking density by the incorporation of polymerizable groups, [15][16][17] improving ame retardancy by phosphorylation of the cured products, 18 and others.…”

“…[19][20][21][22][23][24][25][26][27][28][29][30][31][32] To cure 1,3-benzoxazines, thermally accelerated polymerization has been the main focus for most researchers for a long time. To date, very few compounds, including phenolic compounds, [39][40][41][42][43][44] thiols, [45][46][47][48][49] benzimidazoles, 50 benzoxazoles, 26,51,52 chitosan ammonium, 53 and some polymers containing aromatic structures 19,21,23 have been reported to construct chemical linkages with benzoxazines. 19,20,[33][34][35] The basic concept of the reaction mechanism is the protonation of the oxygen atom in the oxazine ring, followed by the formation of a zwitter iminium ionic structure, and its subsequent Scheme 1 The polymerization mechanisms of benzoxazine proposed by previous reports.…”

Synthesis and characterization of novel biobased benzoxazines from cardbisphenol and the properties of their polymers

“…1 Thus, we attempted to prepare a thin polybenzoxazine lm by thermally polymerization of the as-synthesized biobased benzoxazines to This journal is © The Royal Society of Chemistry 2015 overcome the shortcomings of bisphenol-A based benzoxazine. 29 There were no bubbles and cracks on the surface of polybenzoxazine lms, exhibiting good lm-forming abilities.…”