Structure-property relations of 55 nm particle-toughened epoxy

Le, Quyen-Huyen and Kuan, Hsu-Chiang and Dai, Jia-Bin and Zaman, Izzuddin and Luong, Lee and Ma, Jun (2010) Structure-property relations of 55 nm particle-toughened epoxy. Polymer, 51 . pp. 4867-4879. ISSN 0032-3861

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Abstract

55-nm rubber particles significantly toughened two epoxy systems without loss of Young’s modulus, tensile strength and glass transition temperature. Transmission Electron Microscopy (TEM) showed that the nanoparticles are uniformly dispersed in matrix and have blurred interface with epoxy. 5 wt% rubber nanoparticles increased the critical strain energy release rate (G1c) of Jeffamine D230 (J230)-cured epoxy from 175 J/m2 to 1710 J/m2, while the 10 wt% increased G1c of diaminodiphenyl sulfone (DDS)-cured epoxy from 73 J/m2 to 696 J/m2. This is explained by comparing the surface–surface interparticle distance and total particle surface of nanocomposites with those of composites. The higher the matrix stiffness, the more nanoparticles needed for toughening. Although the 10 wt% J230-cured nanocomposite showed a 50% larger size of stress-whitened zone than the 5 wt% J230-cured nanocomposite, the 5 wt% nano- composite showed a higher toughness. These nanoparticles were found to pose barriers to the vibration of crosslinked matrix molecules, leading to higher glass transition temperatures. While the matrix shear banding caused by nanoparticle expansion and growth is the major toughening mechanism for the J230- cured nanocomposites, the matrix plastic void growth and deformation are most probably the major mechanisms for the DDS-cured system. Under tensile loading, the nanoparticles in the DDS-cured epoxy created fibrils of 100-200 nm in diameter and 3-5 m m in length. TEM analysis in front of a subcritically propagated crack tip showed a number of voids of 30-500 nm in diameter in the vicinity of the crack, implying that rubber nanoparticles expanded, grew and deformed under loading. Unlike conventional epoxy/rubber composites in which all of the rubber particles in the crack front cavitated under loading, only a portion of the nanoparticles in this study expanded to create voids. Huang and Kinloch’s model developed from composites was found not fit well into these nanocomposites.

Item Type:Article
Uncontrolled Keywords:nanocomposite; structure-property relation; toughening mechanism
Subjects:T Technology > TA Engineering (General). Civil engineering (General) > TA401-492 Materials of engineering and construction. Mechanics of materials
Divisions:Faculty of Mechanical and Manufacturing Engineering > Department of Engineering Mechanics
ID Code:6238
Deposited By:Dr Izzuddin Zaman
Deposited On:09 Dec 2014 14:45
Last Modified:09 Dec 2014 14:45

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