Title: Peel Strength of Glass Fiber-Epoxy Composites with Thermoplastic Interlayers under Different Environmental Conditions

Authors: Sagar M. Doshi, Shashank Sharma, Kyle Morris, Joseph M. Deitzel, Shridhar Yarlagadda, John W. Gillespie Jr.

DOI: 10.33599/nasampe/s.22.0764

Abstract: The extensive use of fiber-reinforced composites in army applications is highly dependent on developing composites with improved delamination resistance under a wide range of environmental conditions and loading scenarios. These material systems not only need excellent mechanical and structural properties, but they must be durable and resistant to large scale delaminations under both low and high-velocity impact events. Interlayer toughening mechanisms have widely been used for enhancing the interlaminar delamination resistance of composite materials.

In this research, key mechanisms that affect the peel strength of composites with thermoplastic polyurethane (TPU) interlayer and plain weave S2 glass fabric and two different epoxy systems – RDL-RDC (by Huntsman Corporation) and SC-15 are discussed. A floating roller peel test is used for characterizing the peel strength. Peel tests are conducted at extreme cold and hot operating temperatures as defined by the Department of DefenseMIL-STD-810G. Peel strengths and the different failure mechanisms at various temperatures will be evaluated and discussed. At room temperature, a cohesive TPU failure is observed. At 76 C and -55 C, very different failure modes are observed, along with a significant drop in the peel strength compared to the room temperature.

References: [1] D. J. Bull, A. E. Scott, S. M. Spearing, and I. Sinclair, ""The influence of toughening-particles in CFRPs on low velocity impact damage resistance performance,"" Compos. Part A Appl. Sci. Manuf., vol. 58, pp. 47–55, Mar. 2014, doi: 10.1016/J.COMPOSITESA.2013.11.014. [2] Y. Zeng, H. Y. Liu, Y. W. Mai, and X. S. Du, ""Improving interlaminar fracture toughness of carbon fibre/epoxy laminates by incorporation of nano-particles,"" Compos. Part B Eng., vol. 43, no. 1, pp. 90–94, Jan. 2012, doi: 10.1016/J.COMPOSITESB.2011.04.036. [3] B. Ashrafi et al., ""Enhancement of mechanical performance of epoxy/carbon fiber laminate composites using single-walled carbon nanotubes,"" Compos. Sci. Technol., vol. 71, no. 13, pp. 1569–1578, Sep. 2011, doi: 10.1016/J.COMPSCITECH.2011.06.015. [4] Y. Tang, L. Ye, Z. Zhang, and K. Friedrich, ""Interlaminar fracture toughness and CAI strength of fibre-reinforced composites with nanoparticles – A review,"" Compos. Sci. Technol., vol. 86, pp. 26–37, Sep. 2013, doi: 10.1016/J.COMPSCITECH.2013.06.021. [5] F. . Ko and T. Chou, ""Three-dimensional fabrics for composites,"" Text. Struct. Compos., pp. 129–171, 1989. [6] K. Dransfield, C. Baillie, and Y. W. Mai, ""Improving the delamination resistance of CFRP by stitching—a review,"" Compos. Sci. Technol., vol. 50, no. 3, pp. 305–317, Jan. 1994, doi: 10.1016/0266-3538(94)90019-1. [7] A. P. Mouritz, ""Review of z-pinned composite laminates,"" Compos. Part A Appl. Sci. Manuf., vol. 38, no. 12, pp. 2383–2397, Dec. 2007, doi: 10.1016/J.COMPOSITESA.2007.08.016. [8] T. Abe, ""A-VaRTM Process and Z-Anchor Technology for Primary Aircraft Structure,"" 2003, Accessed: Jan. 28, 2022. [Online]. Available: https://ci.nii.ac.jp/naid/10018580595/. [9] M. Yasaee, I. P. Bond, R. S. Trask, and E. S. Greenhalgh, ""Mode I interfacial toughening through discontinuous interleaves for damage suppression and control,"" Compos. Part A Appl. Sci. Manuf., vol. 43, no. 1, pp. 198–207, Jan. 2012, doi: 10.1016/J.COMPOSITESA.2011.10.009. [10] T. K. Tsotsis, ""Interlayer toughening of composite materials,"" Polym. Compos., vol. 30, no. 1, pp. 70–86, Jan. 2009, doi: 10.1002/PC.20535. [11] S. E. Boyd, T. A. Bogetti, J. M. Staniszewski, B. D. Lawrence, and M. S. Walter, ""Enhanced delamination resistance of thick-section glass-epoxy composite laminates using compliant thermoplastic polyurethane interlayers,"" Compos. Struct., vol. 189, pp. 184–191, Apr. 2018, doi: 10.1016/J.COMPSTRUCT.2018.01.062. [12] N. H. Nash, D. Ray, T. M. Young, and W. F. Stanley, ""The influence of hydrothermal conditioning on the Mode-I, thermal and flexural properties of Carbon/Benzoxazine composites with a thermoplastic toughening interlayer,"" Compos. Part A Appl. Sci. Manuf., vol. 76, pp. 135–144, Sep. 2015, doi: 10.1016/J.COMPOSITESA.2015.04.023. [13] (contributing author) Gillespie J.W. Jr., ""Composite Armored Vehicle Advanced Technology Demonstrator (CAV-ATD) Design Guide,"" in United Defense, L.P Ground Systems Division, Contract DAAE97-94-C-R011, 1999, vol. August. [14] A. Gawandi, L. A. Carlsson, T. A. Bogetti, and J. W. Gillespie, ""Mechanics of discontinuous ceramic tile core sandwich structure: Influence of thermal and interlaminar stresses,"" Compos. Struct., vol. 92, no. 1, pp. 164–172, Jan. 2010, doi: 10.1016/J.COMPSTRUCT.2009.07.022. [15] J. W. Gillespie, L. A. Carlsson, A. A. Gawandi, and T. A. Bogetti, ""Fatigue crack growth at the face sheet-core interface in a discontinuous ceramic-tile cored sandwich structure,"" Compos. Struct., vol. 94, no. 11, pp. 3186–3193, Nov. 2012, doi: 10.1016/J.COMPSTRUCT.2012.05.021. [16] K. S. Alfredsson, A. A. Gawandi, J. W. Gillespie, L. A. Carlsson, and T. A. Bogetti, ""Stress analysis of axially and thermally loaded discontinuous tile core sandwich with and without adhesive filled core gaps,"" Compos. Struct., vol. 93, no. 7, pp. 1621–1630, Jun. 2011, doi: 10.1016/J.COMPSTRUCT.2011.01.015. [17] K. S. Alfredsson, A. A. Gawandi, J. W. Gillespie, L. A. Carlsson, and T. A. Bogetti, ""Flexural analysis of discontinuous tile core sandwich structure,"" Compos. Struct., vol. 94, no. 5, pp. 1524–1532, Apr. 2012, doi: 10.1016/J.COMPSTRUCT.2011.11.028. [18] X. G. Huang, J. W. Gillespie, V. Kumar, and L. Gavin, ""Mechanics of integral armor: discontinuous ceramic-cored sandwich structure under tension and shear,"" Compos. Struct., vol. 36, no. 1–2, pp. 81–90, Sep. 1996, doi: 10.1016/S0263-8223(96)00068-2. [19] ""ASTM D3167 Standard Test Method for Peel Resistance of Adhesives,"" Annu. B. ASTM Stand., vol. 10, no. Reapproved 2017, pp. 14–16, 2010, doi: 10.1520/D3167-10R17.1. [20] S. M. Doshi, N. Manohoaran, B. Z. Haque, J. M. Deitzel, and J. W. Gillespie, Jr., ""Investigating the Influence of Environmental Conditioning on Epoxy Resins At Quasistatic and High Strain Rates for Material Operating Limit,"" 2021, doi: 10.12783/asc36/35745. [21] K. M. Immordino, S. H. McKnight, and J. W. Gillespie Jr, ""In-Situ Evaluation of the Diffusion of Epoxy and Amine in Thermoplastic Polymers,"" J. Adhes., vol. 65, pp. 115–129, 1998, doi: 10.1080/00218469808012242. [22] G. L. Wilkes, P. J. Makarewicz, and H. D. Weigmann, ""Interactions between Solvents and Polymers in the Solid State,"" http://dx.doi.org/10.1080/15321797608065780, vol. 15, no. 2, pp. 279–393, Jan. 2007, doi: 10.1080/15321797608065780. [23] G. Rajagopalan, C. Narayanan, J. W. Gillespie, and S. H. McKnight, ""Diffusion and reaction of epoxy and amine in polysulfone-transport modeling and experimental validation,"" Polymer (Guildf)., vol. 41, no. 24, pp. 8543–8556, Nov. 2000, doi: 10.1016/S0032-3861(00)00251-2. [24] G. Rajagopalan, K. M. Immordino, J. W. Gillespie, and S. H. McKnight, ""Diffusion and reaction of epoxy and amine in polysulfone studied using Fourier transform infrared spectroscopy: experimental results,"" Polymer (Guildf)., vol. 41, no. 7, pp. 2591–2602, Mar. 2000, doi: 10.1016/S0032-3861(99)00418-8. [25] G. Rajagopalan, J. W. Gillespie, and S. H. McKnight, ""Diffusion of reacting epoxy and amine monomers in polysulfone: a diffusivity model,"" Polymer (Guildf)., vol. 41, no. 21, pp. 7723–7733, Oct. 2000, doi: 10.1016/S0032-3861(00)00131-2. [26] R. Don, J. G. Jr, 643,390 SH McKnight - US Patent 5, and undefined 1997, ""Bonding techniques for high performance thermoplastic compositions,"" Google Patents, Accessed: Jan. 28, 2022. [Online]. Available: https://patents.google.com/patent/US5643390A/en. [27] S. Mahdi and J. W. Gillespie, ""Finite element analysis of tile-reinforced composite structural armor subjected to bending loads,"" Compos. Part B Eng., vol. 35, no. 1, pp. 57–71, Jan. 2004, doi: 10.1016/J.COMPOSITESB.2003.10.001. [28] K. S. Alfredsson, T. A. Bogetti, L. A. Carlsson, J. W. Gillespie, and A. Yiournas, ""Flexure of beams with an interlayer: symmetric beams with orthotropic adherends,"" J. Mech. Mater. Struct., vol. 3, no. 1, pp. 45–62, Mar. 2008, doi: 10.2140/JOMMS.2008.3.45. [29] K. S. Alfredsson, J. W. Gillespie, L. A. Carlsson, T. A. Bogetti, and A. Yiournas, ""Flexure analysis of unsymmetric orthotropic beams with an interlayer,"" Int. J. Solids Struct., vol. 46, no. 10, pp. 2093–2110, May 2009, doi: 10.1016/J.IJSOLSTR.2008.07.024. [30] P. D. Samuel et al., ""Improving damage tolerance of plain weave S-2 glass thick-section composites subjected to high energy impact,"" 2022. [31] F. Ozdil and L. A. Carlsson, ""Plastic zone estimates in mode I interlaminar fracture of interleaved composites,"" Eng. Fract. Mech., vol. 41, no. 5, pp. 645–658, Mar. 1992, doi: 10.1016/0013-7944(92)90151-4.

Conference: SAMPE 2022

Publication Date: 2022/05/23

SKU: TP22-0000000764

Pages: 12

Price: $24.00