Blends of epoxy resins and polyphenylene oxide as processing aids and toughening agents 2: Curing kinetics, rheology, structure and properties

Abstract

The curing behaviour, chemorheology, morphology and dynamic mechanical properties of epoxy − polyphenylene oxide (PPO) blends were investigated over a wide range of compositions. Two bisphenol A based di-epoxides − pure and oligomeric DGEBA − were used and their cure with primary, tertiary and quaternary amines was studied. 4,4′ -methylenebis(3-chloro-2,6-diethylaniline) (MCDEA) showed high levels of cure and gave the highest exotherm peak temperature, and so was chosen for blending studies. Similarly pure DGEBA was selected for blending due to its slower reaction rate because of the absence of accelerating hydroxyl groups. For the PPO:DGEBA340/MCDEA system, the reaction rate was reduced with increasing PPO content due to a dilution effect but the heat of reaction were not significantly affected. The rheological behaviour during cure indicated that phase separation occurred prior to gelation, followed by vitrification. The times for phase separation, gelation and vitrification increased with higher PPO levels due to a reduction in the rate of polymerization. Dynamic mechanical thermal analysis of PPO:DGEBA340/MCDEA clearly showed two glass transitions due to the presence of phase separated regions where the lower T g corresponded to an epoxy-rich phase and the higher T g represented the PPO-rich phase. SEM observations of the cured PPO:DGEBA340/MCDEA blends revealed PPO particles in an epoxy matrix for blends with 10 wt% PPO, co-continuous morphology for the blend with 30 wt% PPO and epoxy-rich particles dispersed in a PPO-rich matrix for 40wt% and more PPO.

Blends of epoxy-amine resins with poly(phenylene oxide) as processing aids and toughening agents: I. Uncured systems

“…Two epoxies with different molecular weights were studied as potential plasticizers for PPO: (1) a pure form of DGEBA, coded DGEBA340, with a molecular weight of 340 g mol −1 ( n = 0, see Scheme ) from Aldrich and (2) an oligomer of DGEBA, coded DGEBA381, with a molecular weight of 381 g mol −1 ( n = 0.15, see Scheme ) and containing 15 mol% of hydroxyl groups obtained as Araldite Algy 9708–1 from Ciba‐Geigy. In a companion paper we investigate several curing agents for these monomers and show that 4,4′‐methylenebis(3‐chloro‐2,6‐diethylaniline) (MCDEA; supplied by Aldrich), shown in Scheme , is the favoured material. Thus in the present paper PPO:MCDEA blends are also studied.…”

Phosphaphenanthrene-containing borate ester as a latent hardener and flame retardant for epoxy resin

“…Yield 86.7%. 1 Characterization and instruments NMR spectra were recorded using a Bruker AV 300 NMR spectrometer. Fourier transform infrared (FTIR) spectra were recorded using a Bruker Vertex 70 FTIR spectrophotometer and potassium bromide pellets.…”

“…Epoxy resins (EPs) have excellent electrical insulation, mechanical properties and adhesivity, and have been widely used in various industrial fields . They are classified as one‐pot and two‐pot in terms of reactivity of the hardeners used.…”

“…Epoxy resins (EPs) have excellent electrical insulation, mechanical properties and adhesivity, and have been widely used in various industrial fields. 1 They are classified as one-pot and two-pot in terms of reactivity of the hardeners used. The one-pot handling EPs usually employ thermally latent hardeners, which are inert under ambient temperature and can be transformed into activated species to induce the curing reaction of EPs upon exposure to appropriate external heating stimulation.…”

Synthesis and properties of cured epoxy mixed resin systems modified by polyphenylene oxide for production of high‐frequency copper clad laminates

“…The use of PPO modified epoxy resin not only improves the dielectric and thermal resistance of epoxy resin, but also improves the poor film forming ability and solvent resistance of PPO [12][13][14][15][16][17]. However, compatibility between PPO resin and epoxy resin is generally poor, with phase separation often occurring during the curing process [13,[18][19][20][21].…”