A low concentrated polystyrene (PS) additive to epoxy is used, since it is able to reduce the curing reaction rate but not at the cost of increasing viscosity and decreasing glass transition temperature of the curing epoxy. The modified epoxy is cocured with a compatible thermoplastic interleaf during the vacuum assisted resin transfer molding (VARTM) to toughen the interlaminar of the composites. Using viscometry, the solubilities of thermoplastics (TPs) polycarbonate (PC), polyetherimide (PEI), and polysulfone (PSU) are determined to predict their compatibility with epoxy. The diffusion and precipitation process between the most compatible polymer PSU and epoxy formed semi-interpenetration networks (semi-IPN). To optimize bonding adhesion, these diffusion and precipitation regions were studied via optical microscopy under curing temperatures from 25 °C to 120 °C and PS additive concentrations to epoxy of 0–5%. Uniaxial tensile tests were performed to quantify the effects of diffusion and precipitation regions on composite delamination resistance and toughness. Crack paths were observed to characterize crack propagation and arrest mechanism. Fracture surfaces were examined by scanning electron microscopy (SEM) to characterize the toughening mechanism of the thermoplastic interleaf reinforcements. The chemically etched interface between diffusion and precipitation regions showed semi-IPN morphology at different curing temperatures. Results revealed deeper diffusion and precipitation regions increase energy required to break semi-IPN for crack propagation resulting in crack arrests and improved toughness.
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July 2017
Research-Article
Interlaminar Toughening of GFRP—Part I: Bonding Improvement Through Diffusion and Precipitation
Dakai Bian,
Dakai Bian
Department of Mechanical Engineering,
Columbia University,
New York, NY 10027
e-mail: db2875@columbia.edu
Columbia University,
New York, NY 10027
e-mail: db2875@columbia.edu
Search for other works by this author on:
Bradley R. Beeksma,
Bradley R. Beeksma
Department of Mechanical Engineering,
Columbia University,
New York, NY 10027
Columbia University,
New York, NY 10027
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D. J. Shim,
D. J. Shim
GE Global Research,
Niskayuna, NY 12309
Niskayuna, NY 12309
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Marshall Jones,
Marshall Jones
GE Global Research,
Niskayuna, NY 12309
Niskayuna, NY 12309
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Y. Lawrence Yao
Y. Lawrence Yao
Department of Mechanical Engineering,
Columbia University,
New York, NY 10027
Columbia University,
New York, NY 10027
Search for other works by this author on:
Dakai Bian
Department of Mechanical Engineering,
Columbia University,
New York, NY 10027
e-mail: db2875@columbia.edu
Columbia University,
New York, NY 10027
e-mail: db2875@columbia.edu
Bradley R. Beeksma
Department of Mechanical Engineering,
Columbia University,
New York, NY 10027
Columbia University,
New York, NY 10027
D. J. Shim
GE Global Research,
Niskayuna, NY 12309
Niskayuna, NY 12309
Marshall Jones
GE Global Research,
Niskayuna, NY 12309
Niskayuna, NY 12309
Y. Lawrence Yao
Department of Mechanical Engineering,
Columbia University,
New York, NY 10027
Columbia University,
New York, NY 10027
1Corresponding author.
Manuscript received November 21, 2016; final manuscript received February 14, 2017; published online March 24, 2017. Assoc. Editor: Donggang Yao.
J. Manuf. Sci. Eng. Jul 2017, 139(7): 071010 (9 pages)
Published Online: March 24, 2017
Article history
Received:
November 21, 2016
Revised:
February 14, 2017
Connected Content
A companion article has been published:
Interlaminar Toughening of GFRP—Part II: Characterization and Numerical Simulation of Curing Kinetics
Citation
Bian, D., Beeksma, B. R., Shim, D. J., Jones, M., and Lawrence Yao, Y. (March 24, 2017). "Interlaminar Toughening of GFRP—Part I: Bonding Improvement Through Diffusion and Precipitation." ASME. J. Manuf. Sci. Eng. July 2017; 139(7): 071010. https://doi.org/10.1115/1.4036126
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