Interlaminar Toughening

Fig. 8.2. Composite mode I interlaminar fracture toughness, G[, as a function of respective neat resin toughness, G] ( ) Kim et al. (1992) (O) from Russell and Street (1987) ( ) toughened thermosets and ( ) thermoplasties from Hunston et al. (1987) (A) from Bradley (1989a) ( ) from Jordan and Bradley...

The improvement of damage resistance and tolerance in interlaminar fracture and under impact loading for the toughened matrix composites is at the expense of other important mechanical properties, such as inferior stiffness and hot/wet compressive strength (Evans and Masters, 1987). These trade offs appear to be associated with the reduction in matrix modulus and glass transition temperature (Jordan et al., 1989). 

Hibbs, M.F., Tse, M.K. Bradley, W.L. (1987). Interlaminar fracture toughness and real time fracture mechanisms of some toughened graphite/epoxy composite. In Toughened Composites, ASTM STP 937 (N.J. Johnston ed,), ASTM, Philadelphia, PA, pp. 115-130. 

Table VI. Interlaminar Fracture Energies of Epoxy-Graphite Composites TGDDM-DGEBA-DDS System Toughened with MEAc Polymer...

Finally, the basic Adhesive B formulation was toughened using the MEAc core-shell polymer and used as the matrix for an epoxy-graphite fiber composite. The mode II interlaminar fracture toughness, GIIc, was increased from 500 J/m2 to 890 J/m2 by the presence of the acrylic core-shell toughener. 

Sela N, Oshai O. Interlaminar fracture toughness and toughening of laimuated composite materials a review. Composites 1989 20 423-35. http //dx.doi.org/10.1016/ 0010-4361(89)90211-5. 

Kinloch AJ, Mohammed RD, Taylor AC, Sprenger S, Egan D (2006) The interlaminar toughness of carbon-fibre reinforced plastic composites using hybrid-toughened matrices. J Mater Sci 41(15) 5043-5046... 

Finer nanofibers resulted in better improvement in the interlaminar properties without compromising the in-plane performance of the toughened composites [146], thus decreasing the fiber diameters is favorable. It must be noted that (critical energy release rate... 

Increasing the thickness even more can have negative outcome. For instance, Liu et at [143] found that when the sum of the thickness of nanofibrous toughening layers reaches approximately one tenth of that of the composite, the flexural modulus and the interlaminar shear properties began to drop. When increasing the amount of nanofibers this effect becomes even more significant. 

The effect of weave structure on the mode-1 interlaminar fracture energy (Gic) of E-glass/rubber-modified VER laminates was examined [229]. Different types of E-glass fibers were used, i.e. plain weave, twiU weave, quadran 4-harness satin weave, and 8-hatness satin weave with weave index 2,3,4, and 8, respectively, to determine the influence of weave pattern on the delamination resistance of toughened VER laminates. 

Arai A, Noro Y, Sugimoto K-I and Endo M (2008) Mode I and mode II interlaminar fracture toughness of CFRP laminates toughened by carbon nanofiber interlayer, Compos Sci Technol 68 516-525. 

---