Effects of morphology on toughening of tetrafunctional epoxy resins with poly(ether imide)

Cho, J.B.; Hwang, Jongkook; Cho, K.; An, Jung-Chul; Park, C.E.

doi:10.1016/0032-3861(93)90005-u

Cited by 129 publications

(82 citation statements)

References 8 publications

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“…Various authors, e.g. [41][42][43], have observed changes in morphology, into a co-continuous phase, for higher concentrations of thermoplastics in epoxy. As the amount of modifier is increased, the viscosity increases and the rate of phase separation reduces.…”

Section: Morphologymentioning

confidence: 99%

The microstructure and fracture performance of styrene–butadiene–methylmethacrylate block copolymer-modified epoxy polymers

Chong

Taylor

2013

J Mater Sci

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The microstructure and fracture performance of an anhydride-cured epoxy polymer modified with two poly(styrene)-b-1,4-poly(butadiene)-b-poly(methyl methacrylate) (SBM) block copolymers were investigated in bulk form, and when used as the matrix material in carbon fibre reinforced composites. The 'E21' SBM block copolymer has a higher butadiene content and molecular weight than the 'E41'. A network of aggregated spherical micelles was observed for the E21 SBM modified epoxy, which became increasingly interconnected as the SBM content was increased. A steady increase in the fracture energy was measured with increasing E21 content, from 96 to 511 J/m 2 for 15 wt% of E21. Well-dispersed 'raspberry'-like SBM particles, with a sphere-on-sphere morphology of a poly(styrene) core covered with poly(butadiene) particles, in an epoxy matrix were obtained for loadings up to 7.5 wt% of E41 SBM. This changed to a partially phase-inverted structure at higher E41 contents, accompanied by a significant jump in the measured fracture energy to 1032 J/m 2 at 15 wt% of E41. The glass transition temperatures remained unchanged with the addition of SBM, indicating a complete phase separation. Electron microscopy and cross polarised transmission optical microscopy revealed localised shear band yielding, debonding and void growth as the main toughening mechanisms. Significant improvements in fracture energy were not observed in the fibre composites, indicating poor toughness transfer from the bulk to the composite. The fibre bridging observed for the unmodified epoxy matrix was reduced due to better fibre-matrix adhesion. The size of the crack tip deformation zone in the composites was restricted by the fibres, hence reducing the measured fracture energy compared to the bulk for the toughest matrix materials.

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Section: Morphologymentioning

confidence: 99%

The microstructure and fracture performance of styrene–butadiene–methylmethacrylate block copolymer-modified epoxy polymers

Chong

Taylor

2013

J Mater Sci

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“…However, the further use of epoxies is limited because of their inherent brittleness, poor crack resistance. In recent years, the feasibility of toughening highly crosslinked networks with high modulus and high T g thermoplastics has been investigated [7][8][9][10][11][12]. Addition of thermoplastics into thermosets leads to different phenomena.…”

Section: Introductionmentioning

confidence: 99%

Effect of polyethersulfone and N,N’-bismaleimido-4,4’-diphenyl methane on the mechanical and thermal properties of epoxy systems

Rajasekaran¹,

Alagar²,

Chozhan³

2008

Express Polym. Lett.

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Abstract. In order to improve thermo mechanical properties of cured epoxy resin, hydroxyl terminated polyethersulfone (PES) and N,N′-bismaleimido-4,4′-diphenyl methane (BMI) were incorporated to diglycidyl ether of bisphenol A (DGEBA) type epoxy resin and cured with diaminiodiphenylmethane (DDM). The resulting hybrid matrices, in the form of castings, were characterized for their mechanical properties like tensile, flexural and impact strength. Differential scanning calorimetry, dynamic mechanical analysis and thermogravimetric analysis of the matrices were also performed to determine the glass transition temperature and thermal stability of the matrix systems. The results obtained from mechanical and thermal studies indicated that the incorporation of polyethersulfone into epoxy resin improved the toughness and thermal stability of the systems. This is attributed to the formation of interpenetration polymer networks (IPNs) composed of the epoxy network and the linear PES. The incorporation of BMI into polyethersulfone modified epoxy systems increased thermal stability, glass transition temperature, tensile and flexural properties and decreased the impact strength. Scanning electron microscopy studies of polyethersulfone modified epoxy and BMI incorporated polyethersulfone modified epoxy systems exhibit homogeneous morphology confirming efficient chemical interaction and formation of intercrosslinked network structure.Keywords : polymer composites, thermal properties, mechanical properties, morphology, moisture absorption eXPRESS Polymer Letters Vol.2, No.5 (2008) [339][340][341][342][343][344][345][346][347][348] Available online at www.expresspolymlett.com DOI: 10.3144/expresspolymlett.2008.40 homogeneous hybrid thermoplastic modified epoxy with low fractions of thermoplastics [18]. It is reported that the incorporation of high performance thermoplastics into a thermoset resin system leads to significant improvements in mechanical properties [9,[19][20][21][22] [28][29][30][31][32]. Bismaleimides posses high crosslinking ability, high glass-transition temperature, high thermal ability, high char yield, excellent fire resistance, superior specific strength and specific modulus, and low water absorption. In continuation of our earlier studies, an attempt has been made in the present investigation to improve both toughness and thermo-mechanical properties of epoxy resin by incorporating hydroxyl terminated polyethersulfone (PES) and N,N′-bismaleimido-4,4′-diphenyl methane(BMI). Materials and methodsEpoxy resin [diglycidyl ether of bisphenol A (DGEBA)] LY556 (epoxy equivalent 189 and viscosity 10 000 cP) and 4,4′-diaminodiphenylmethane (DDM) were obtained from Ciba-Geigy (India). N,N′-bismaleimido-4,4′-diphenyl methane was synthesized in our laboratory as per the reported procedure ( Figure 1) [33]. Hydroxyl terminated polyethersulfone was supplied by Jilin University, China was used as received. The chemical structures of materials used are presented in Figure 2.340 Rajasekaran et al. -eXPRESS Polymer Let...

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“…The rate of network formation determines whether thermodynamics or kinetics will dominate the final outcome of phase separation [25]. For a TGDDM/DDS system with a PEI content of less than 20 phr, thermally cured for 2 h at 140 °C followed by 2 h at 190°C, the morphology of the system consists of spherical inclusions of PEI dispersed in the epoxy matrix [27]. For the same loading of PEI but using cure schedule of 88 hours at 70 °C a cocontinuous phase structure was obtained because curing at a low temperature for a long time results in the gelation of the resin mixture in the early stages of phase separation [27].…”

Section: Fracture Surfaces Of the Matricesmentioning

confidence: 99%

Flexural and interlaminar shear strength properties of carbon fibre/epoxy composites cured thermally and with microwave radiation

Nightingale

Day

2002

Composites Part A: Applied Science and Manufacturing

127

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The ease of heating an epoxy resin with microwaves depends, among other factors, on the dielectric properties of its components at the frequency of the radiation used. The majority of the papers published on the microwave curing of reinforced epoxy resin composites have used widely available DGEBA type resins and amine hardeners such as 4,4'-diaminodiphenylsulphone (DDS). This paper investigates the use of two epoxy systems where the choice of resin and hardener was based on their measured dielectric loss factors. System 1 contained a resin and hardener with higher loss factors than those used in System 2. The two systems were formulated with polyetherimide (PEI) as a toughening agent. Unidirectional carbon fibre prepregs were prepared from both systems. Composites were laid up from these prepregs which were then cured in three different ways: autoclave curing, partial autoclave curing followed by microwave post-curing, and microwave curing. System 1 composites had greater flexural properties and interlaminar shear strengths than System 2 composites when autoclave cured. Flexural properties and interlaminar shear strengths were greater for System 2 in the microwave post-cured composites. When fully microwave cured the properties were similar. In the microwave cured composites the flexural and interlaminar shear properties were influenced by the structure of the phase separated PEI and the void content. AbstractThe ease of heating an epoxy resin with microwaves depends, among other factors, on the dielectric properties of its components at the frequency of the radiation used. The majority of the papers published on the microwave curing of reinforced epoxy resin composites have used widely available DGEBA type resins and amine hardeners such as 4,4'-diaminodiphenylsulphone (DDS). This paper investigates the use of two epoxy systems where the choice of resin and hardener was based on their measured dielectric loss factors. System 1 contained a resin and hardener with higher loss factors than those used in System 2.The two systems were formulated with polyetherimide (PEI) as a toughening agent. Unidirectional carbon fibre prepregs were prepared from both systems. Composites were laid up from these prepregs which were then cured in three different ways: autoclave curing, partial autoclave curing followed by microwave post-curing, and microwave curing. System 1 composites had greater flexural properties and interlaminar shear strengths than System 2 composites when autoclave cured. Flexural properties and interlaminar shear strengths were greater for System 2 in the microwave post-cured composites. When fully microwave cured the properties were similar. In the microwave cured composites the flexural and interlaminar shear properties were influenced by the structure of the phase separated PEI and the void content.

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Effects of morphology on toughening of tetrafunctional epoxy resins with poly(ether imide)

Cited by 129 publications

References 8 publications

The microstructure and fracture performance of styrene–butadiene–methylmethacrylate block copolymer-modified epoxy polymers

The microstructure and fracture performance of styrene–butadiene–methylmethacrylate block copolymer-modified epoxy polymers

Effect of polyethersulfone and N,N’-bismaleimido-4,4’-diphenyl methane on the mechanical and thermal properties of epoxy systems

Flexural and interlaminar shear strength properties of carbon fibre/epoxy composites cured thermally and with microwave radiation

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