Role of intrinsic flaws upon flexural behaviour of a thermoplastic modified epoxy resin

Giannotti, Marina I.; Galante, Maria Jose; Oyanguren, Patricia Angelica; Vallo, Claudia Ines

doi:10.1016/s0142-9418(02)00124-1

Cited by 43 publications

(50 citation statements)

References 13 publications

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“…The scatter obtained in the measurements of the Young's modulus of the epoxy resin and the blends with a 5 and 10% of thermoplastic content was so high that the moderate increase observed in the average value of the blend with 20% is not reliable. The value of the Young's modulus of the epoxy resin is in agreement with the flexural values reported by previous researchers,15, 23–25 and the tensile module reported by Grillet et al26 Even so, the tendency of the Young's modulus with the PS‐ co ‐PA content obtained from the tensile tests differs with that measured via DMTA experiments in this very system by Prolongo et al20 There, the storage modulus in the glassy state increased from 2.55 GPa for the pure epoxy resin to 2.75 GPa for the blends with 20 wt % of PS‐ co ‐PA. The discrepancy in the values obtained by these two methods is due to the inherent difficulty of measuring the Young's modulus.…”

Section: Resultssupporting

confidence: 91%

Fracture properties of epoxy/poly(styrene‐co‐allylalcohol) blends

Salazar

Prolongo

Rodrı́guez

2007

J of Applied Polymer Sci

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ABSTRACT:The epoxy/polystyrene system is characterized by a poor adhesion between the constituent phases, which determines its mechanical properties. The adhesion can be improved via blends based on epoxy resin and random copolymers, poly(styrene-co-allylalcohol) (PS-co-PA). In this work, the influence of PS-co-PA content and the good adhesion between the phases on the tensile properties and the fracture toughness achieved through instrumented Charpy tests have been investigated. The tensile strength and the deformation at break showed an increase in the PS-co-PA content while the Young's modulus remained the same. The tensile fracture surfaces revealed that the improvement of these magnitudes was mainly due to a crack deflection mechanism. Also, the fracture toughness of the blends was superior to that of the pure epoxy resin. The main operating toughening mechanism was crack deflection. The fractographic analysis showed that $ 80% of the particles were broken, and the crack tended to divert from its original path through the broken PS-co-PA particles. The remaining particles were detached from the epoxy resin, and the holes left suffered plastic deformation. Analytical models were used to predict successfully the toughness due to these mechanisms.

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Section: Resultssupporting

confidence: 91%

Fracture properties of epoxy/poly(styrene‐co‐allylalcohol) blends

Salazar

Prolongo

Rodrı́guez

2007

J of Applied Polymer Sci

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“…Thus, the higher values of flexural modulus of samples subjected to a post-curing treatment are attributed to a reduced amount of non-reacted monomer. The high data scatter observed in flexural strength values is associated to a brittle rupture of the test specimens [27,28]. Brittle fracture occurs due to the propagation of a crack in the material.…”

Section: Mechanical Propertiesmentioning

confidence: 99%

“…Flaws of variable sizes, shapes and orientations with respect to the applied load are possible. Hence, variable crack sizes and their orientations with respect to the applied load can account for the observed scatter of fracture strengths, when nominally identical specimens are tested under nominally identical loading conditions [27,28].…”

Section: Mechanical Propertiesmentioning

confidence: 99%

Polymerization of methacrylate resins photoinitiated by camphorquinone and bulky amine-functionalized silsesquioxanes

et al. 2012

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Polyhedral oligomeric silsesquioxanes (SSQO) functionalized with bulky amino groups were prepared by a two-stage synthesis procedure. In a first stage, a modified organotrimethoxysilane was synthesized by reacting 1 mol of N-(b-aminoethyl)-c-aminopropyltrimethoxysilane with 3 mol of 1,2-epoxy-3-phenoxypropane. The second stage consisted of the hydrolytic condensation of the modified silane catalyzed by formic acid. Methacrylate resins were activated for visible light polymerization by the addition of camphorquinone (CQ) in combination with different mass fractions of SSQO. The progress of monomer conversion versus irradiation time showed that the CQ/SSQO pair is an efficient photoinitiator system because a fast reaction and high conversion results from 60 s irradiation at 600 mW/ cm 2 . The SSQO were incorporated up to 22 wt% in the methacrylate resin without compromising the flexural or the compressive properties of the final material.

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“…However, their brittle nature due to its high cross-link density and poor resistance to crack propagation limits the applications in advanced aerospace structures. To overcome this problem various Engineering thermoplastics like polyether sulfone [2,3], polycarbonate [4,5], polyethylene tere phthalate [6,7], poly ether ether ketone/hydroxyl terminated poly (ether ether ketone) with pendant methyl groups (PEEKMOH) [8,9], Poly ether ether ketone/hydroxyl terminated poly ether ether ketone with pendant tertiary butyl groups [10][11][12][13] or poly (cyanoarylene ether)/hydroxyl terminated poly arylene ether nitrile with pendant tertiary butyl groups [14,15] have been used as a toughness modifiers for epoxy resin without sacrificing other thermomechanical properties. However no evidence of improvement in modulus, gas barrier property and in coefficient of thermal expansion (CTE) was reported in the literature.…”

Section: Introductionmentioning

confidence: 99%

Thermoplastic toughened layered silicate epoxy ternary nanocomposites—Preparation, morphology, and thermomechanical properties

Asif

Rao

Saseendran

et al. 2009

Polymer Engineering & Sci

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Epoxy-clay ternary nanocomposites were processed by melt blending of hydroxyl terminated poly (ether ether ketone) oligomer with pendant methyl groups (PEEKMOH) with diglycidyl ether of bisphenol A (DGEBA) epoxy resin along with organically modified montmorillonite (OMC-OH) followed by curing with 4,4 0 -diamino diphenyl sulfone. Small angle X-ray diffraction and transmission electron microscopy revealed an intercalated morphology. Tensile, flexural, storage, and loss moduli were increased whereas the tensile, flexural, and impact strength and glass transition temperature were decreased with increase in clay content for the PEEKMOH toughened epoxy system. Fracture toughness and percentage strain were increased by 66% and 45% respectively whereas the coefficient of the thermal expansion was decreased by 27% with the incorporation of 1 phr OMC-OH to the PEEKMOH toughened epoxy system compared with neat epoxy. The scanning electron microscope pictures of fracture and tensile failed surfaces revealed crack path deflection and ductile fracture with the incorporation of OMC-OH confirming the improvement in toughness. The domain size and the distance between the domains of thermoplastic phase were decreased with the addition of nanoclay into the epoxy matrix indicating the restriction of the growth mechanism by nucleation during phase separation.

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Role of intrinsic flaws upon flexural behaviour of a thermoplastic modified epoxy resin

Cited by 43 publications

References 13 publications

Fracture properties of epoxy/poly(styrene‐co‐allylalcohol) blends

Fracture properties of epoxy/poly(styrene‐co‐allylalcohol) blends

Polymerization of methacrylate resins photoinitiated by camphorquinone and bulky amine-functionalized silsesquioxanes

Thermoplastic toughened layered silicate epoxy ternary nanocomposites—Preparation, morphology, and thermomechanical properties

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