Bionic boron/silicon-modified phenolic resin system with multifunctional groups: synthesis, thermal properties and ablation mechanism

Abstract

A kind of silicon-and-boron-modified phenolic–formaldehyde resin (SBPF) with excellent thermal stability was fabricated via a simple two-step method and used for the matrix of ablation materials. The structure and thermal stability of the modified phenolic–formaldehyde resins (PFs) were characterised. The results showed that boron and silicon elements have been incorporated into SBPF in the form of a chemical bond. Meanwhile, the cured products showed an increase in graphite structure and a decrease in disordered structure due to the incorporation of boron and silicon. Compared with the ordinary phenolic resin, the initial thermal degradation temperature and charring yield at 800°C of SBPF increased by 73°C and 15 wt%, respectively. Further, the modified PFs, nano-Al(2)O(3) powders, glass powders and vitreous silica fibres were used to obtain a novel ceramizable phenolic moulding composite. The morphology, chemical composition and ablative characteristics of the composites were explored. The results showed that a compact and homogeneous SiO(2)–Al(2)O(3) layer formed on the ablated surface and protected the carbonised matrix and fibres from further oxidation. Compared with the ordinary PF composites, the SBPF composites showed a highly decreased linear/mass ablation rates, indicating the synergistic effect of boron and silicon modification on the enhanced ablation property.

Keywords

• filled polymers
• scanning electron microscopy
• X-ray diffraction
• bonds (chemical)
• thermal stability
• thermal analysis
• silicon compounds
• curing
• pyrolysis
• ceramics
• carbon
• heat treatment
• Raman spectra
• resins
• boron
• powders
• X-ray chemical analysis
• Fourier transform infrared spectra
• silicon
• alumina
• fibre reinforced plastics
• nanoparticles
• glass
• oxidation
• multifunctional groups
• thermal properties
• ablation mechanism
• ablation materials
• Fourier transform infrared spectroscopy
• silicon elements
• graphite structure
• disordered structure
• modified PFs
• ordinary phenolic resin
• initial thermal degradation temperature
• charring yield
• energy dispersive spectroscopy
• ablated surface
• SBPF composites
• thermal stability
• scanning electron microscopy
• bionic boron-silicon-modified phenolic resin system
• two-step method
• X-ray diffraction
• Raman spectroscopy
• chemical bond
• cured products
• glass powders
• vitreous silica fibres
• ceramizable phenolic moulding composite
• oxyacetylene torch tests
• homogeneous layer
• compact layer
• carbonised matrix
• oxidation
• highly decreased linear-mass ablation rates
• boron elements
• nanoAl(2)O(3) powders
• thermogravimetric analysis
• temperature 800.0 degC
• Al(2)O(3)-SiO(2)
• B
• Si