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Effects of particle size and rubber content on fracture toughness in rubber‐modified epoxies
Author(s) -
Kim D. S.,
Cho K.,
Kim J. K.,
Park C. E.
Publication year - 1996
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.10463
Subject(s) - materials science , natural rubber , composite material , fracture toughness , toughness , particle size , epoxy , particle (ecology) , emulsion polymerization , diglycidyl ether , bisphenol a , polymerization , polymer , chemical engineering , oceanography , engineering , geology
The effects of particle size of core‐shell rubber on the fracture toughness of rubber‐modified epoxies were investigated. Various sizes of core‐shell rubber particles, from 0.16 to 1.2 μm in diameter, were synthesized by seeded emulsion polymerization. Particle size effects were clearly seen for lower crosslinked diglycidyl ether of bisphenol A (DGEBA)/piperidine resin. Fracture toughness increased as the particle size of core‐shell rubber decreased from 1.2 to 0.4 μm. On the other hand, fracture toughness was constant in this range of particle sizes for higher crosslinked DGEBA/diaminodiphenylmethane (DDM) resin. Cavitation in the rubbery core and shear deformation in the matrix are the toughening mechanisms for DGEBA/piperidine resin, whereas cavitation is the only mechanism for DGEBA/DDM resin. Toughening effectiveness decreased with <0.2 μm core‐shell rubber particles since they are difficult to cavitate. The effects of core‐shell rubber content on fracture toughness of rubber‐modified epoxies were also examined. The optimum rubber content for maximum toughness of rubber‐modified epoxies decreased with decreased particle size of core‐shell rubber in shear deformable DGEBA/piperidine resin. But the fracture toughness of rubber‐modified DGEBA/DDM resins increased as the rubber content increased.