Abstract
In this experiment, terephthalyl alcohol was used as a modifier to modify phenol under both acidic and alkaline conditions to obtain modified phenols with different molecular structures. Subsequently, the modified phenols reacted with paraformaldehyde in an alkaline environment. After foaming and curing, a modified phenolic foam with high heat aging resistance was obtained. The molecular structure was characterized via Fourier transform infrared spectrometry (FT-IR) and nuclear magnetic resonance spectroscopy (13C NMR). The results showed that two different structures of phenolic resin can be successfully prepared under different conditions of acid and alkali. The modified phenolic foam was tested by thermogravimetric analysis. In addition, the modified phenolic foam was tested for mass change rate, dimensional change rate, powdering rate, water absorption rate, and compressive strength before and after aging. The results show that the modified phenolic foam has excellent performance. After heat aging for 24 h, the mass loss rate of the modified phenolic foam obtained by acid catalysis was as low as 4.5%, the pulverization rate was only increased by 3.2%, and the water absorption of the modified phenolic foam increased by 0.77%, which is one-third that of the phenolic foam. Compared with the phenolic foam, the modified phenolic foam shows good heat aging resistance.
Highlights
Known as the “king of insulation materials”, phenolic foam is a kind of foam material with good heat insulation, good sound insulation, low thermal conductivity, and an easy molding process [1,2].In addition, phenolic foam has the advantages of resistance to flame penetration, an absence of dripping, a self-extinguishing ability, and low smoke generation in the event of an open flame [3,4].Phenolic resin as a foaming matrix is a resole phenolic resin obtained by polycondensation of phenol and paraformaldehyde
The results showed that polyethylene glycol significantly improved the toughness and impact strength of the foam, but the thermal stability of the foam had a slightly adverse effect [4]
In order to improve the thermal stability of phenolic foam [35] as well as its aging resistance, this experiment chose terephthalyl alcohol to chemically modify phenolic foam
Summary
Known as the “king of insulation materials”, phenolic foam is a kind of foam material with good heat insulation, good sound insulation, low thermal conductivity, and an easy molding process [1,2]. The foam properties, especially the toughness, of the modified phenolic resin as a foaming matrix were greatly improved. In order to improve the thermal stability of phenolic foam [35] as well as its aging resistance, this experiment chose terephthalyl alcohol to chemically modify phenolic foam. In order to improve the thermomechanical properties and thermal stability, Zixuan Lei used epoxy-polyhedral oligomeric silsesquioxane-modified novolac phenolic resin, and prepared a novel organic–inorganic hybrid network with hexamethylenetetramine [37]. After the modified phenol with a different molecular structure is obtained, a modified phenolic foam with excellent heat aging resistance was prepared using paraformaldehyde
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