Adhesive and thermal characteristics of maleimide-functional novolac resins

Abstract

ABSTRACT:A novel, addition-curable maleimide-functional novolac phenolic resin was evaluated for adhesive properties such as lap shear strength and T-peel strength using aluminium adherends, when thermally self-cured and cocured with epoxy resins. The adhesive properties of the self-cured resin, although inferior at ambient temperature, improved at high temperature and were found to depend on the cure conditions. When cocured with epoxy resin, the adhesive properties improved significantly and showed a strong dependence on the nature of the epoxy resin used, on the stoichiometry of the reactants, on the concentration of imide groups in the phenolic resin, and on the extent of polymerization of the maleimide groups. Optimum adhesive properties were obtained for novolac resins with a moderate concentration of maleimide groups, taken on a 1 : 1 hydroxyl-epoxy stoichiometry with a novolac epoxy resin. In comparison to the conventional novolac, the imide-novolac contributed to improved adhesion and better adhesive property retention at higher temperature when cured with the novolac-epoxy resin.

Fabrication and evaluation of structural film adhesive using oxazolidinone modified novolac epoxy resin

“…Cured thermoset in combination of DGEBA and naphthalene moieties resulted in a T g of greater than 250 °C . Multiple epoxy functionalities from EPNs impart highly crosslinked network with a curative . Oxazolidinone ring system plays a pivotal role in engineering materials due to their exceptional mechanical and thermal attributes .…”

“…1,2,[4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] However, plenty of reports are available on various advanced epoxy resins useful for extensive applications in high-tech sectors. [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] Single part epoxy adhesive based on epoxy novolac resin (EPN) derived from 4,4 0 -dihydroxybenzophenone was reported by Baby et al The material was cured using DICY and the system offered improved glass-transition temperature (T g ) and it retained its adhesive strength up to 150 C. 24 Cured thermoset in combination of DGEBA and naphthalene moieties resulted in a T g of greater than 250 C. 31 Multiple epoxy functionalities from EPNs impart highly crosslinked network with a curative. [34][35][36][37] Oxazolidinone ring system plays a pivotal role in engineering materials due to their exceptional mechanical and thermal attributes.…”

Novel macromolecular epoxy resin curing agent containing biphenyl and maleimide moieties: Preparation, curing kinetics, and thermal properties of its cured polymer

“…For these reason, modifications of epoxy resins or curing agents in both the backbone and pendant groups have been continuously investigated to improve the thermal and physical properties of cured epoxy resins. Many studies have been reported that improved the heat resistance of epoxy resins by increasing the crosslink density of the cured epoxy resin3 or by introducing bulky structures, such as dicyclopentadiene,4 biphenyl,5, 6 naphthalene,7, 8 fluorine, or maleimide 9–11…”

“…Many studies have been reported that improved the heat resistance of epoxy resins by increasing the crosslink density of the cured epoxy resin 3 or by introducing bulky structures, such as dicyclopentadiene, 4 biphenyl, 5,6 naphthalene, 7,8 fluorine, or maleimide. [9][10][11] On the other hand, imide polymers are known for their high thermal stability, and it has been well reported in the literature that when chemical structures of the cured epoxy polymers are constituted with aromatic and/or heterocyclic rings, their thermal resistance is superior to those based on flexible or aliphatic chains. 12 Therefore, the use of imide groups to modify the structure of epoxy to enhance its thermal resistance has received great attention in the research community.…”

A Comparative Study of the Preparation and Characterization of Aromatic and Aliphatic Bismaleimides to Produce Modified Siliconized Epoxy Intercrosslinked Matrices for Engineering Applications

“…The development of lightweight modified composite systems which will impart enough fracture toughness, high impact strength, high thermal stability, and improved mechanical properties would allow the use of these products in the place of conventional structural materials for high-performance engineering and aerospace applications (1). Epoxy resin is a versatile and widely accepted matrix material for the fabrication of advanced composites, hardware components, electronic circuit board materials and sealants, radomes, and missile equipment components because of its excellent bonding, physicochemical, thermal, mechanical, dielectric, and aging characteristics (2)(3)(4)(5)(6)(7).…”