Phenolic Foams Toughened with Triethylene Glycol by In Situ Polymerization and Prepolymerization Processes

Abstract

The current work presents the study of the toughening effect of in situ polymerization modification process (In-MP) and prepolymerization modification process (Pre-MP) on triethylene glycol (TEG)-modified phenolic foams (PFs). TEG in situ polymerization-modified phenolic resin (T-In-PR) and TEG prepolymerization-modified phenolic resin (T-Pre-PR) with different molecular structures have been synthesized by two processes using TEG as a modifier. The comparison of the molecular structure and properties of the resins shows that the molecular weight distribution of T-Pre-PR is uniform and its basic properties of resin are better than T-In-PR. The number of benzene ring linkage bridges in the T-Pre-PR structure increases from three to four, which can improve the toughness while stabilizing the intermolecular connection strength. The TEG-modified PFs prepared with TEG-modified phenolic resins exhibit excellent toughness. The fracture displacement of T-Pre-PF was 85.13% higher than those of ordinary PFs, and the pulverization rate was 55.85% lower than those of ordinary PFs. Compared with T-In-PF, the cell shapes of T-Pre-PF were uniform polygonal structures and formed a stable honeycomb-like structure. The cell size distribution of T-Pre-PF was more concentrated than those of T-In-PF and ordinary PFs, and the level of damage of cell wall was low. The maximum bending strength of T-Pre-PF was 0.263 MPa, and the maximum compression strength was 0.160 MPa, which were higher than those of T-In-PF. The findings demonstrate that Pre-MP is more suitable for the preparation of PFs with internal toughening modification by TEG than In-MP.

Investigation of Polyvinyl Alcohol–Phenolic Aldehyde–Polyacrylamide Gel for the Application in Saline Oil Reservoirs for Profile Modification

“…The hydrogen bond is formed between the hydroxyl group in phenolic aldehyde and the polymer containing hydroxyl group, carbonyl group, and ether . The stretching vibration peaks at 1643 and 1407 cm –1 are attributed to the benzene ring. , There are obvious differences between PVA-g-PAM-PF (DI) gel prepared from DI water and PVA-g-PAM-PF (SW) gel prepared from formation saltwater at the hydroxyl (O–H) peak. The FTIR spectra showed that the hydroxyl (O–H) stretching vibration peak of the gel samples shifted more to the low wavenumber region and the absorption band widened, indicating that the addition of PVA with more hydroxyl groups provided hydrogen bond formation, which was beneficial to enhance the molecular chain entanglement inside the gel and improve the mechanical properties.…”

Preparation of High-Toughness Lignin Phenolic Resin Biomaterials Based via Polybutylene Succinate Molecular Intercalation

“…Chemical toughening involves a chemical reaction used to introduce flexible chain segments or graft flexible side chains onto the molecular chains of the phenolic resin to achieve the toughening effect. Commonly used chemical toughening agents include cashew phenol, polyurethane prepolymer, polyvinyl acetal, and carboxylated nitrile rubber [ 16 , 17 ]. Improving the molecular structure is the most direct solution, but there are problems of high costs and long development cycles.…”