Reinforced plastics interface aspects

Reinforced plastics, sometimes called polymer composites, consist of reinforcing fibres or particles embedded in a polymeric matrix. It is now recognized that a third component, called an interphase region, can exist at the interface between the fibre and resin. The properties of the interphase are probably not constant but vary to give a graded region. Thus the environmental durability of a composite material is a complex interplay between the various microstructural aspects of the material, which are ... 

The performance of all Composite materials is dependent on the adhesion between the different phases. In this article, aspects relevant to carbon-fibre reinforced plastics are discussed. There is a parallel article on Fibre-matrix adhesion - glass fibres. A discussion of the fibre-matrix interface can be found in Fibre composites - introduction. 

FR Jones. Interfacial Aspects of Glass Fiber Reinforced Plastics. Proceedings of the International Conference on Interface Phenomena in Composite Materials, September 1989, pp 25-32. 

Finally, it is noteworthy that if water (or indeed other highly polar liquids) is the environment of interest, then metallic and ceramic substrates are those which result in joints most likely to exhibit poor durability. This is a consequence, of course, of the relatively polar nature of their surfaces and their high surface free energies. Thus, ingressing water molecules are preferentially attracted to the surfaces of these substrates and will displace the physisorbed molecules of the adhesive. These comments are also reflected [5,6] in the values of Wa and Wai for joints based upon carbon-fibre-reinforced plastic (CFRP) substrates typically being of the order of 90 mJ/m and 30 mJ/m, respectively. The positive values of both of these terms indicate that the durability of adhesively bonded CFRP joints should not represent a major problem. This is indeed found to be the case, from the aspect of the stability of the interface. (Although problems may arise if (a) the... 

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