Composites, polymer interfaces

Wool, R.P., Polymer Interfaces, Structure and Strength. Hanser Publishers, Munich, 1995. Ishida, H. In Akovali, G. (Ed.), The Interfacial Interactions in Polymeric Composites. Kluwer Academic, Dordrecht, 1993, p. 169. 

The toughness of interfaces between immiscible amorphous polymers without any coupling agent has been the subject of a number of recent studies [15-18]. The width of a polymer/polymer interface is known to be controlled by the Flory-Huggins interaction parameter x between the two polymers. The value of x between a random copolymer and a homopolymer can be adjusted by changing the copolymer composition, so the main experimental protocol has been to measure the interface toughness between a copolymer and a homopolymer as a function of copolymer composition. In addition, the interface width has been measured by neutron reflection. Four different experimental systems have been used, all containing styrene. Schnell et al. studied PS joined to random copolymers of styrene with bromostyrene and styrene with paramethyl styrene [17,18]. Benkoski et al. joined polystyrene to a random copolymer of styrene with vinyl pyridine (PS/PS-r-PVP) [16], whilst Brown joined PMMA to a random copolymer of styrene with methacrylate (PMMA/PS-r-PMMA) [15]. The results of the latter study are shown in Fig. 9. 

Benkoski, J.J., Fredrickson, G.H. and Kramer, E.J., The effect of composition drift on the effectiveness of random copolymer reinforcement at polymer-polymer interfaces. Macromolecules (2001, in press). 

The use of interpenetrating donor-acceptor heterojunctions, such as PPVs/C60 composites, polymer/CdS composites, and interpenetrating polymer networks, substantially improves photoconductivity, and thus the quantum efficiency, of polymer-based photo-voltaics. In these devices, an exciton is photogenerated in the active material, diffuses toward the donor-acceptor interface, and dissociates via charge transfer across the interface. The internal electric field set up by the difference between the electrode energy levels, along with the donor-acceptor morphology, controls the quantum efficiency of the PV cell (Fig. 51). 

Penn, L.S., Tesoro, G.C. and Zhou, H.X. (1988). Some effects of surface-controlled reaction of Kevlar 29 on the interface in epoxy composites. Polym. Composites 9, 184-191. 

Piggott, M. R. (1987). Debonding and friction at fiber-polymer interface. I Criteria for failure and sliding. Composites Sci. Technol. 30, 295-306. 

Wright, W.W. (1990). The carbon fiber-epoxy resin interfaces-a review, part I. In Composite Polymer Vol, 3. (P. Dickin, ed.), pp. 231-401. 

Chua P.S. and Piggott M.R. (1985). The glass fiber-polymer interface IV - Controlled shrinkage polymers. Composites Sci. Technol. 22, 24.5-258. 

Benatar, A. and Gutowski, T.G. (1986). Effects of moisture on interface modified graphite epoxy composites. Polym. Composites 7, 84-90. 

Y. Ivanov, V. Cheshkov and M. Natova Polymer Composite Materials - Interface Phenomena... 

The layered structure of a cast film is controlled by the surface properties during evaporation. Significant compositional gradients can be generated by making use of the natural tendencies of one polymer to migrate toward the air-polymer Interface and the other toward the substrate. Hydrophobicity/hydrophilicity of macromolecules is often cited as the driving force (27, 28). 

Recently, much attention is being placed on fibres-reinforced/polymer systems as subjects of study. It was caused by increasing emphasis on high performance reinforced polymer composites. The concept of acid/base interactions across the fibre/polymer interface was noted particularly and the relevance of acid/base theories to the behaviour of po-... 

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