Epoxy resin Fibre surface treatment

As with aluminium extrusions, so with pultruded fibre reinforced composite profiles. The limit to the size and complexity of these profiles suggests that a modular approach could be adopted towards forming alternative structural configurations from the basic or standard profile shapes by bonding together individual lengths. Composite materials lend themselves to being joined with resin adhesives because they are themselves formed with vinyl ester, polyester or epoxy resins. Cursory surface treatments only, such as mild abrasion, often suffice. 

J. S. Szabo, J. Kaiger-Kocsis, O. Gryshchuk, T. Czigdny (2(X)4) Effect of fibre surface treatment on the mechanical response of ceramic fibre mat-reinforced interpenetrating vinylester/epoxy resins. Compos. ScL Technol. 64, 1717. 

Plastic composites such as glass- or carbon-fibre reinforced materials are often based on polar epoxy or polyester resins, and are therefore compatible with the common adhesives as well as being readily bondable. Surface treatment is required simply to remove contaminants such as oils, dirt, and especially fluorocarbon mould release agents. The two main techniques used to achieve this are ... 

The surface energy of fibres is closely related to the hydrophility of the fibre. Some investigations are concerned with methods to decrease hydrophility. The modification of wood-cellulose fibres with stearic acid [49] causes those fibres to become hydrophobic and improves their dispersion in PR As can be observed in jute reinforced unsaturated polyester resin composites, treatment with polyvinylacetate increases the mechanical properties [50] and moisture repellence. Silane coupling agents may contribute hydrophilic properties to the interface, especially when amino-functional silanes, such as epoxies and urethane silane are used as primers for reactive polymers. The primer may supply much more amine functionality than can possibly react with the resin at the interphase. Those amines, which could not react, are hydrophilic and therefore responsible for the poor water resistance of the bonds. An effective way to use hydrophilic silanes is to blend them with hydrophobic silanes such as phenyltrimethoxysilane. Mixed siloxane primers also have an improved thermal stability, which is typical for aromatic silicones [48]. 

The low density of these fibres - about 0.97 g cm - means that in terms of specific stress and specific modulus (i.e. on a mass per unit length basis) they rank very highly. However, they are limited in composites by their low melting temperatures (about 140°C), tendency to creep, and the need for special surface-activation processes, such as corona discharge treatment, to develop adhesion to matrix polymers. They are sometimes used alone, but more often in hybrid yam and fabric stmctures with glass or carbon fibres in an epoxy or unsaturated polyester resin matrix to improve the impact resistance and energy absorption. Curing temperatures should not exceed 125°C. 

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