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

Abstract

Epoxy film adhesives are of prime importance for the fabrication of lightweight honeycomb structures for aerospace industries. This work involves the synthesis of oxazolidinone modified epoxy novolac resin (EPN‐OXA) via the reaction of EPN and toluene diisocyanate. EPN‐OXA was characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography, and epoxy equivalent weight. EPN‐OXA was blended with solid epoxy resin, polyethersulfone (PES) toughened liquid epoxy resin, dicyandiamide, and aluminum powder to fabricate a film adhesive curing at 170–180 °C. Effect of additives and curative on the adhesive property was studied to optimize the composition. Effect of PES on the optimized composition was studied in detail. The best composition exhibited lap shear strength of 370 ± 10 kgf cm−2 at 25 °C and the strength was retained to 75% at −196 °C and 52% at 120 °C. PES significantly enhanced the interfacial strength at different temperatures (~1.6‐fold at −196 and 25 °C and ~1.8‐fold at 120 °C). It also improved tensile strength and fracture toughness by 1.4‐ and 2‐fold, respectively. The toughening effect of PES was further confirmed by scanning electron microscopy images. PES marginally reduced the glass‐transition temperature and it exhibited no effect on thermal stability. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47520.

Free-Radical Bulk-Photopolymerization Process as a Method of Obtaining Thermally Curable Structural Self-Adhesive Tapes and Effect of Used Type I Photoinitiators

“…There are only very few data about structural adhesive films’ preparation or modification. The latest revealed a moisture effect on commercial structural adhesive film [ 6 ], using epoxy resins modified with oxazolidinone [ 7 ] or polysulfones [ 8 ]. A particular kind of the SATs is those with self-adhesive features.…”

Preparation and UV‐curing properties of oxazolidine‐2‐one based acrylates

“…In addition, oxazolidine‐2‐one is a five‐membered heterocyclic structure with nitrogen and oxygen is more stable than carbamate, 37,38 ring structure acrylates have a lower shrinkage rate than chain acrylate 39 . The polymer with oxazolidine‐2‐one structures has a better comprehensive performance, such as a thermal stability and mechanical properties 40–43 . The UV‐curing system containing oxazolidine‐2‐one groups will have potential application prospects in fields such as 3D printing due to expected lower cured shrinkage and better heat resistance.…”

“…39 The polymer with oxazolidine-2-one structures has a better comprehensive performance, such as a thermal stability and mechanical properties. [40][41][42][43] The UV-curing system containing oxazolidine-2-one groups will have potential application prospects in fields such as 3D printing due to expected lower cured shrinkage and better heat resistance.…”

Exploring the optical and dielectric properties of bifunctional and trifunctional epoxy polymers

“…Knowing the type of the transition is in fact of prime importance, as it greatly conditions the optoelectronic properties of a given material, and therefore its possible applications. Some publications reported the estimated values of the two gaps via the Kubelka-Munk function and determined the nature of transition only by calculation [31,32]. Other works have rightly underlined this difficulty of defining the transition type and made proposals to remove this ambiguity by using the R-squared value to estimate the goodness of the fit of Tauc plots [33].…”