Fiber reinforced polymers debonding

Liao B, Huang Y, Cong G (1997) Influence of modified wood fibers on the mechanical properties of wood fiber-reinforced polyethylene. J Appl Polym Sci 66 1561-1568 Mani P, Satyanarayan KG (1990) Effects of the surface treatments of lignocellulosic fibers on their debonding stress. J Adhes Sci Technol 4 17-24... 

Young and Day [95] used the shift in Raman band frequency of the 1580-cm band in carbon fibers to determine the compressive strain imposed on the carbon fibers by thermal shrinkage and crystallization of the matrix polymer, PEEK, in a carbon fiber-PEEK composite. This allows the estimation of the interfacial stress between the fiber and the composite resin due to processing. The lack of interfacial stress is considered critical to the performance of many fiber-reinforced composites because the interfacial stress adds to the applied stress and can lead to early fracture or debonding of the fiber from the matrix. 

After debonding, friction at the interface has to be overcome [10,37,39,43] in order for pull-out to proceed. Friction at the interface is due to the normal compressive stresses that are caused by the pressure po acting on the fiber from the matrix, where Po is the pressure exerted due to Poisson s contraction of the matrix at the moment the fiber emerges from the polymer. Such stresses arise from resin shrinkage resulting from the curing of the specimen and from dissimilar coefficients of thermal expansion of the matrix and the reinforcing fiber [40,44,48]. 

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