Bis-benzoxazine resins with high char yield and toughness modified by hyperbranched poly(resorcinol borate)

Jing

et al. 2013

Polym. Adv. Technol.

Self Cite

In the present study, a novel aryl‐boron‐containing phenolic resin named as PBPR has been synthesized from phenol and formaldehyde in the presence of phenylboronic acid. The chemical structure of the PBPR was confirmed by Fourier transform infrared, nuclear magnetic resonance and X‐ray photoelectron spectroscopy. The molecular weight, viscosity and curing behavior were examined to demonstrate that PBPRs have better processability than common boric acid‐modified phenolic resin. The thermal stability and fracture toughness of the cured PBPRs were greatly enhanced, where the char yield at 1000°C (nitrogen atmosphere) and the glass transition temperature reached 70.0% and 218°C, respectively. The excellent mechanical and ablative properties of the PBPR composites may have benefited from the good interfacial adhesion between the resin matrix and the reinforced fiber. The flexural strength and the linear ablative rate are 436.8 ± 5.2 MPa and 0.010 mm/sec, respectively. This study opens a new window for the preparation of high‐performance ablative composites by designing a resin matrix containing an aryl‐boron backbone. Copyright © 2013 John Wiley & Sons, Ltd.

Section: Introductionmentioning

confidence: 59%

Synthesis and characterization of novel phenolic resins containing aryl-boron backbone and their utilization in polymeric composites with improved thermal and mechanical properties

Jing

et al. 2013

Polym. Adv. Technol.

Self Cite

Macromol. Rapid Commun.

“…As observed, the interlaminar shear strength (ILSS), flexural strength, and flexural modulus were improved, especially for ILSS. As discussed above, some BOH and SiOEt groups are left in BSiPR; the improved interfacial adhesion between BSiPF and HSF can be assigned to the formation of BOSi and SiOSi structures which are formed by the reaction of BOH and SiOEt in BSiPR and SiOH of the fibers . Therefore, for HSF/PR in Figure S6a, Supporting Information, fibers can be more easily pulled out from the resin matrix.…”

Section: Figurementioning

confidence: 85%

“…As discussed above, some BOH and SiOEt groups are left in BSiPR; the improved interfacial adhesion between BSiPF and HSF can be assigned to the formation of BOSi and SiOSi structures which are formed by the reaction of BOH and SiOEt in BSiPR and SiOH of the fibers. [35][36][37] Therefore, for HSF/PR in Figure S6a, fibers can be more easily pulled out from the resin matrix. The fracture surface is irregular, and many cavities are observed.…”

Section: Doi: 101002/marc201800702mentioning

confidence: 99%

Boric Acid as a Coupling Agent for Preparation of Phenolic Resin Containing Boron and Silicon with Enhanced Char Yield

Yun

Chen

Zhao

et al. 2018

In this study, an innovative, facile, and low‐cost method is developed to prepare phenolic resin (PR) containing boron and silicon (BSiPR). BSiPR is synthesized by a solvent‐free, one‐pot method using boric acid as the coupling agent instead of silane, and methyltriethoxysilane as the silicon source. The results show that boron and silicon elements are introduced into PR via BOC and BOSi structures. The char yield of the resulting resin at 800 °C is improved to 76%. The reasons for higher char yield are investigated. The formation of BOC can reduce the content of phenolic hydroxyl, which helps to decrease the weight loss. B2O3 is also formed at 400 °C, and it can prevent the release of carbon oxides. Moreover, thermally stable BOSi and SiO structures remain stable during the pyrolysis. In addition, the mechanical and ablative properties of fiber‐reinforced composites are also enhanced.

“…These results can be related to the unique structure of HBPs: the branched structure, multiple reactive terminal groups and internal cavities . Si et al . used hyperbranched poly(resorcinol borate) to modify benzoxazine resin and found both the storage modulus and impact strength were increased.…”

Section: Introductionmentioning

confidence: 99%

An investigation of the relationship between the performance of polybenzoxazine and backbone structure of hyperbranched epoxy modifiers

Liu

et al. 2017

Polymer International

Novel hyperbranched polyether epoxies (HBPEEs) with various backbone structures were synthesized using a one‐pot A2 + B3 approach. These highly effective HBPEEs were incorporated into polybenzoxazine (PBOZ) network at various concentrations without cure‐induced phase separation. Effects of backbone structure and loading amount on the curing behavior and mechanical and thermal properties of PBOZ/HBPEE hybrid were investigated. The general trend shows that the impact strength, flexural strength and storage modulus all first increase and then decrease with filler content. For the backbone structure study, HBPEE‐3, which has the highest proportion of benzene rings, can simultaneously improve impact strength, flexural strength and storage modulus. In contrast, HBPEE‐1 and HBPEE‐2, which have fewer benzene rings and smaller intramolecular cavities, perform worse in terms of mechanical and thermal properties. Both backbone structure and loading of HBPEEs play important roles in determining the crosslink density and structures of non‐phase‐separated network. In addition, the simultaneous improvement can be explained by enhanced crosslinking density, structure of modifier, reduced hydrogen bond network and higher fractional free volume according to dynamic mechanical and thermomechanical analyses. © 2017 Society of Chemical Industry