Preparation and Properties of the 3-pentadecyl-phenol In Situ Modified Foamable Phenolic Resin

Abstract

In this present study, 3-pentadecyl-phenol was selected as a modifier to prepare a foamable phenolic resin with excellent performance, which was successfully prepared by in situ modification. Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (1H NMR, 13C NMR) were used to test and characterize the molecular structure of the modified resin. The results showed that 3-pentadecyl-phenol successfully modified the molecular structure of phenolic resin with a reduction in the resin gel time. The effect of changing the added amount of 3-pentadecyl-phenol on the mechanical properties, microstructure, and flame retardancy of the modified foam was investigated. The results showed that when the amount of added 3-pentadecyl-phenol was 15% of the total amount of phenol, this resulted in the best toughness of the modified foam, which could be increased to 300% compared to the bending deflection of the unmodified phenolic foam. The cell structure showed that the modified phenolic foam formed a more regular and dense network structure and the closed cell ratio was high. Furthermore, the compressive strength, bending strength, and limited oxygen index were improved, while the water absorption rate was lowered. However, the foam density could be kept below 40 mg/cm3, which does not affect the load.

Recent Trends of Foaming in Polymer Processing: A Review

“…Polypropylene (PP) foam is widely used in daily necessities, military industries, transportation, and aerospace, such as in the production of various seat cushions, thermal insulation materials, shockproof materials, packaging materials, and building materials [16,17,18]. Phenolic foam is mainly used in the fields of architecture, automobiles, electrical and electronic applications, the iron and steel industry, and aerospace [19,20,21,22]. It can meet the requirements of heat insulation and combustion-resistant building materials for large-scale sports and entertainment venues, high-rise buildings, and high-speed vehicles.…”

Preparation and Properties of Acetoacetic Ester-Terminated Polyether Pre-Synthesis Modified Phenolic Foam

“…There are absorption peaks at 756.10 cm −1 in the ortho-substitution bending vibration region of the benzene ring, and 829.12 cm −1 in the para-substitution bending vibration region of the benzene ring. The IR bands of the C–O group of phenol and C–O group of hydroxymethyl appeared at 1153.18 cm −1 and 1108.32 cm −1 [2]. Compared with the basic phenolic resin, the IR spectra of polyether phenolic resin showed that the stretching vibration peaks of the polyether methylene are located at 2937.54 cm −1 and 2860.77 cm −1 .…”

“…As shown in Figure 2, δ = 6.5–7.4 ppm at position h is the proton peak of hydrogen in the benzene ring, δ = 4.8–5.1 ppm at position f is the proton peak of hydrogen in phenol, δ = 4.2–4.7 ppm at position e is the hydrogen proton peak of the methyl group in the hydroxymethyl group, δ = 3.6–3.8 ppm at position d is the proton peak of the hydrogen in the linking benzene ring –CH 2 –, and δ = 1.9–2.1 ppm at position c is the hydrogen proton peak of hydroxymethyl –OH [2]. Compared with the basic phenolic resin, the 1 H NMR spectra of polyether phenolic resin showed that the δ = 1.0–1.2 ppm at position a is the hydrogen proton peak of hydrogen in the polyether skeleton, while δ = 1.7–1.8 ppm at position b is the hydrogen proton peak of hydrogen in the terminal methyl group of acetoacetic ester, while δ = 5.8–5.9 ppm at position g is the hydrogen proton peak of hydrogen in the methylene group of acetoacetic ester.…”

“…However, its shortcomings are also notable, including its low elongation, brittleness, poor toughness, etc. [2]. The benzene ring in the molecular structure is only connected by a methylene group, and the resin forms a uniform and stable three-dimensional network structure.…”

“…Therefore, we selected the pre-synthesis modification method in the chemical modification to improve the performance of phenolic foam. The pre-synthesis modification method [2] first involves the modification of phenol, and then the reaction of the modified phenol with formaldehyde to synthesize a new resin. The synthesized new resin and the base phenolic resin are foam-cured at a certain ratio to obtain a modified phenolic foam with excellent properties.…”