Examining the influence of bisphenol A on the polymerisation and network properties of an aromatic benzoxazine

Abstract

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms ABSTRACT: A series of reactive blends, comprising a commercial benzoxazine monomer, 2,2- bis(3,4-dihydro-3-phenyl-2H-1,3-benzoxazine)propane, and bisphenol A is prepared andcharacterized. Thermal analysis and dynamic rheology reveal how the introduction of up to 15 wt % bisphenol A lead to a significant increase in reactivity (the exothermic peak maximum of thermal polymerization is reduced from 245 ºC to 215 ºC), with a small penalty in glass transition temperature (reduction of 15 K), but similar thermal stability (onset of degradation = 283 ºC, char yield = 26 %). With higher concentrations of bisphenol A (e.g. 25 wt %), a significantly more reactive blend is produced (exothermic peak maximum = 192 ºC), but with a significantly lower thermal stability (onset of degradation = 265 ºC, char yield = 22 %) and glass transition temperature (128 ºC). Attempts to produce a cured plaque containing 35 wt % bisphenol A were unsuccessful, due to brittleness. Molecular modelling is used to replicate successfully the glass transition temperatures (measured using thermal analysis) of a range of copolymers.

Synthesis of novel tri‐benzoxazine and effect of phenolic nucleophiles on its ring‐opening polymerization

“…A 6.9–9.5% weight loss was observed at this temperature range, which can be attributed to the degradation of phenolic terminal groups at the chain end in the networked polybenzoxazines (Scheme ) . Ishida et al also reported such degradation (first mass loss at 150–200 °C) in cured bisphenol‐A benzoxazine (B‐a)/bisphenol‐A (BPA) blends, where BPA branches or side chains were formed with higher bisphenol‐A content . The major amount of weight loss in NPBzs was observed only above 250 °C (17–32%), thus implies that the main chain degradation in NPBzs occurring quite similar to poly(T‐Bz) (26%) or other traditional polybenzoxazines at higher temperature …”

“…However, all NPBzs showed a very high thermal stability (50–150 °C higher) as compared to previously reported LPBz based on bifunctional benzoxazine and MR (i.e., 3a, Table ) . Thermal stability was also found to be higher in relative to commercial bisphenol‐A based polybenzoxazine (MT35600: T d5 = 289 °C; T d20 = 355 °C) . The char residue was varied from 65 to 79% and in the order of poly(T‐Bz) ≥ DHN > PG > MR > HQ > 3a (55%) > poly(B‐a) (36%).…”

“…Among the various phenolic nucleophiles used, MR, HQ, PG, and DHN were found to be successful for ring‐opening addition reaction with T‐Bz at 140 °C due to their high nucleophilicity and obtained a networked polybenzoxazine (NPBz). Moreover, a very low curing exotherm ( T p : 115–133 °C) was observed in the DSC scan of benzoxazine with MR/HQ/PG/DHN, to the best of our knowledge, this is the first time reporting such a low curing maxima compared to several modification (including catalysts or side group functionalization) reported in the literature (mostly T p > 180 °C) . Even though the NPBZs showed an initial decomposition around 200 °C, the main backbone decomposition occurred at higher temperature ( T d20 at 350–465 °C) as indicated by their DTA curves.…”

Low-Dissipation Thermosets Derived from Oligo(2,6-dimethyl phenylene oxide)-containing Benzoxazines

“…Polybenzoxazines feature for special characteristics such as a moderate-to-high thermal property, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] moderate electrical property, [19] low water absorption, [20] and low surface energy. [21] Low-dielectric benzoxazines have been reported (1) by Chang et al through Mannich condensation of bisphenol F/ 4-(trifluoromethyl)aniline/formaldehyde.…”

Modification of benzoxazine with aryl-ether-ether-ketone diphenol: preparation and characterization

“…However, phenols can not only catalyze the ring-opening reaction of benzoxazine monomers and lower their curing temperature, but will also react with benzoxazines through electrophilic substitution reactions to form similar chemical structures to polybenzoxazine. Hamerton et al 49 added 15 wt% of bisphenol-A into bisphenol-A/aniline benzoxazine (BA-a), and found that the exothermic peak temperature of BA-a was decreased from 245 C to 215 C because of the catalytic action of phenol. Kolanadiyil et al 50 studied the catalytic effect of various phenolic nucleophiles on a trifunctional benzoxazine (T-BZ).…”