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.

Synthesis and Thermal Degradation Study of Polyhedral Oligomeric Silsesquioxane (POSS) Modified Phenolic Resin

“…Phenolic resin is an indispensable foundational material in the field of aerospace thermal protection materials due to its excellent thermal stability, solvent resistance and structural integrity, and it is also a precursor of C/C composite materials [1,2]. However, some of the properties of phenolic resin still need to be further improved to meet the growing performance requirements of aerospace thermal protection materials [3][4][5]. The adverse characteristics that need to be ameliorated include a moderate thermal oxidation stability, inherent brittleness and residual char yield [6,7].…”

Improving Pore Characteristics, Mechanical Properties and Thermal Performances of Near-Net Shape Manufacturing Phenolic Resin Aerogels

“…However, the BA and LBA3 wet gel exhibited suitable flexibility. This might be associated with the addition of BPR [ 36 , 37 ]. On the other hand, the BA wet gel presented the lowest shrinkage rate, but its rigidity was much lower than that of the LBA3 wet gel, implying that the pore characteristic should also be responsible for the shrinkage of wet gels.…”

Research Progress in Boron-Modified Phenolic Resin and Its Composites

“…Factors that affect the activity of the reaction system, such as catalyst, aldehyde-phenol-boron ratio, reaction temperature, and time, affect the performance of BPF [13]. Therefore, the exploration of the optimal synthesis conditions for the salicyl alcohol method has received a lot of attention [14][15][16][17]. For instance, when the phenol:formaldehyde:boric acid molar ratio is 1:1.5:0.4, the condensation temperature is 60~70 °C, the boron esterification temperature is 105~120 °C, and ammonia water (pH = 8~9) is used as a catalyst, the Factors that affect the activity of the reaction system, such as catalyst, aldehyde-phenolboron ratio, reaction temperature, and time, affect the performance of BPF [13].…”