Modification of cyanate ester resin by poly(ethylene phthalate) and related copolyesters

Abstract

Aromatic polyesters were prepared and used to improve the brittleness of the cyanate ester resin. The aromatic polyesters include poly(ethylene phthalate) (PEP) and poly(ethylene phthalate-co-1,4-phenylene phthalate). The polyesters were effective modifiers for improving the brittleness of the cyanate ester resin. For example, inclusion of 20 wt % PEP (MW 19,800) led to a 120% increase in the fracture toughness (K IC ) with retention in flexural properties and a slight loss of the glass transition temperature compared to the mechanical and thermal properties of the unmodified cured cyanate ester resin. The microstructures of the modified resins were examined by scanning electron microscopy and dynamic viscoelastic analysis. The thermal stability of the modified resins was lower than that of the unmodified resin as determined by thermogravimetric analysis. The water absorptivity of the modified resin increased significantly, compared to that of the unmodified cured cyanate ester resin. The toughening mechanism was discussed in terms of the morphological and dynamic viscoelastic behaviors of the modified cyanate ester resin system.

Toughening of cyanate ester resin by N‐phenylmaleimide–N‐(p‐hydroxy)phenyl‐maleimide–styrene terpolymers and their hybrid modifiers

“…The unmodified cyanate ester resin was transparent, as reported previously 19. The HPMS‐modified resins were also transparent.…”

“…Modification of the cyanate ester resin has been carried out on the basis of information on the toughening of epoxy and bismaleimide resins by thermoplastics such as aromatic polyesters and N ‐phenylmaleimide–styrene copolymer (PMS) in our laboratory 10–18. More recently, we examined poly(ethylene phthalate) (PEP) and related copolyesters as modifiers for cyanate ester resin 19. PEP is an effective modifier for improvement in toughness, but the low water absorptivity of the parent resin is deteriorated because of the change in the structure of the cyanate matrices.…”

Synthesis and properties of a liquid oligomeric cyanate ester resin

“…Even though most commercial CEs possess good flammability and high temperature properties, they are far too brittle to be widely used in structural applications. Many additives have been used to strengthen the resulting CE thermoset including epoxies [3,11,12], polyesters [13] and bismalimides [2,[12][13][14] with varying success. Co-curing the CEs with these polymers can result in non-miscibility, which has both desired and undesired effects on the physical and thermal properties of the polymeric matrix [15,16].…”

Modification of cyanate ester resin by soluble polyarylates

“…Recently, modifications of thermosets with engineering thermoplastics have been studied as alternatives to reactive rubber toughening from the viewpoint of preserving the mechanical and thermal properties of the matrix resins. Engineering thermoplastics examined as modifiers for cyanate ester resin include polysulfone,4–7 poly(ether sulfone),5, 6 poly(ether imide),4, 7 polyarylate,4 poly(ether ketone ketone)6, 8 and phenolphthalein‐based poly(arylene ether)s 9. Blends of cyanate ester resin with thermosets such as epoxy and bismaleimide resins were also examined to improve toughness 10, 11…”