Curing behavior of 4,4′-diamonodiphenyl methane-based benzoxazine oligomers/bisoxazoline copolymers and the properties of their cured resins

• Published in: Journal of applied polymer science Vol. 99; no. 4; pp. 1359 - 1366
• Main Authors: Li, Shengfang, Wang, Luoli
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 15.02.2006; Wiley
• Subjects: 1,3‐phenylene bisoxazoline; 3-phenylene bisoxazoline; 4,4′‐diamonodiphenyl methane; 4′-diamonodiphenyl methane; Applied sciences; benzoxazine; Chemical properties; curing behavior; Exact sciences and technology; Polymer industry, paints, wood; Properties and testing; Technology of polymers; Electrical properties; Molecular structure; Crosslink density; benzoxazine; curing behavior; Experimental study; Property processing relationship; Phenolic resin; Thermal stability; Thermal properties; Diamine; Waterproofness; Curing(plastics); Novolac; 1,3-phenylene bisoxazoline; Reaction mechanism; Electric resistivity; Phenoplasts; Kinetics; Chemical properties; 4,4'-diamonodiphenyl methane; Oxazole derivatives
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.22310

1,3‐Phenylene bisoxazoline is synthesized and characterized. The optimal synthetic conditions for yield (92%) are as follows: reaction temperature = 115°C; ratio (mol) of ethanolamine to 1,3‐dicyanobenzene = 2.5 : 1; ratio (mol) of zinc acetate to 1,3‐dicyanobenzene = 0.055; reaction time = 6 h. 4,4′‐diamonodiphenyl methane‐based benzoxazine and its oligomers (Oligo‐Da) are synthesized and characterized. The curing behavior and properties of the Oligo‐Da/1,3‐PBO copolymer resins are investigated. It was found that the cure induction time and cure time of the molten mixture from Oligo‐Da/1,3‐PBO could be reduced, compared with that from Oligo‐Ba/1,3‐PBO, especially above 175°C. The reason lies in that the bisphenol generated in ring opening of Ba has more steric hindrance than the phenol generated in ring opening of Da because of isopropyl group. Thus, the Mannich bridge structure in the Da polymer is relatively much easier to form between the ortho positions of phenolic hydroxyl groups than that in the Ba polymer. Curing temperature of Oligo‐Da/1,3‐PBO could be lowered with triphenylphosphite as a catalyst. SEM results confirm that 1,3‐PBO could toughen Oligo‐Da system when the mol ratio of 1,3‐PBO and Oligo‐Da is ≤1 because of the formation of ether–amide bonds. However, a brittle fracture surface is observed because of too higher crosslinking density of the cured resin, when the mol ratio of 1,3‐PBO and Oligo‐Da is >1. The cured resin from Oligo‐Da/1,3‐PBO has superior heat resistance, electrical insulation, and water resistance than that from Oligo‐Ba/1,3‐PBO. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1359–1366, 2006